Hello Andrew, Russell,
The KDB/NMI core support has been merged into v3.7-rc1, so the only ARM bits are pending now.
I addressed all the comments ~two month ago, and since then just resending these patches. I know we're all busy, so no blaming. :) But then let's pass this via -mm?
Short description of the KDB/FIQ debugger:
The FIQ debugger is a facility that can be used to debug situations when the kernel stuck in uninterruptable sections, e.g. the kernel infinitely loops or deadlocked in an interrupt or with interrupts disabled. On some development boards there is even a special NMI button, which is very useful for debugging weird kernel hangs.
And FIQ is basically an NMI, it has a higher priority than IRQs, and upon IRQ exception FIQs are not disabled. It is still possible to disable FIQs (as well as some "NMIs" on other architectures), but via special means.
Old changelogs and a full rationale for these patches can be found here:
v1-v5, rationale: http://lkml.org/lkml/2012/9/10/2 v6: http://lkml.org/lkml/2012/9/10/2 v7: http://lkml.org/lkml/2012/9/13/367 v8: http://lkml.org/lkml/2012/9/19/525 v9: http://lkml.org/lkml/2012/9/24/538
Thanks! Anton.
-- arch/arm/Kconfig | 19 ++++ arch/arm/common/vic.c | 28 +++++ arch/arm/include/asm/hardware/vic.h | 2 + arch/arm/include/asm/kgdb.h | 8 ++ arch/arm/kernel/Makefile | 1 + arch/arm/kernel/entry-armv.S | 167 +-------------------------- arch/arm/kernel/entry-header.S | 170 ++++++++++++++++++++++++++++ arch/arm/kernel/kgdb_fiq.c | 124 ++++++++++++++++++++ arch/arm/kernel/kgdb_fiq_entry.S | 87 ++++++++++++++ arch/arm/mach-versatile/Makefile | 1 + arch/arm/mach-versatile/kgdb_fiq.c | 31 +++++ 11 files changed, 472 insertions(+), 166 deletions(-)
Just move the macros into header file as we would want to use them for KGDB FIQ entry code.
The following macros were moved:
- svc_entry - usr_entry - kuser_cmpxchg_check - vector_stub
To make kuser_cmpxchg_check actually work across different files, we also have to make kuser_cmpxchg64_fixup global.
Signed-off-by: Anton Vorontsov anton.vorontsov@linaro.org --- arch/arm/kernel/entry-armv.S | 167 +--------------------------------------- arch/arm/kernel/entry-header.S | 170 +++++++++++++++++++++++++++++++++++++++++ 2 files changed, 171 insertions(+), 166 deletions(-)
diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S index 0f82098..0f15368 100644 --- a/arch/arm/kernel/entry-armv.S +++ b/arch/arm/kernel/entry-armv.S @@ -136,57 +136,6 @@ common_invalid: b bad_mode ENDPROC(__und_invalid)
-/* - * SVC mode handlers - */ - -#if defined(CONFIG_AEABI) && (__LINUX_ARM_ARCH__ >= 5) -#define SPFIX(code...) code -#else -#define SPFIX(code...) -#endif - - .macro svc_entry, stack_hole=0 - UNWIND(.fnstart ) - UNWIND(.save {r0 - pc} ) - sub sp, sp, #(S_FRAME_SIZE + \stack_hole - 4) -#ifdef CONFIG_THUMB2_KERNEL - SPFIX( str r0, [sp] ) @ temporarily saved - SPFIX( mov r0, sp ) - SPFIX( tst r0, #4 ) @ test original stack alignment - SPFIX( ldr r0, [sp] ) @ restored -#else - SPFIX( tst sp, #4 ) -#endif - SPFIX( subeq sp, sp, #4 ) - stmia sp, {r1 - r12} - - ldmia r0, {r3 - r5} - add r7, sp, #S_SP - 4 @ here for interlock avoidance - mov r6, #-1 @ "" "" "" "" - add r2, sp, #(S_FRAME_SIZE + \stack_hole - 4) - SPFIX( addeq r2, r2, #4 ) - str r3, [sp, #-4]! @ save the "real" r0 copied - @ from the exception stack - - mov r3, lr - - @ - @ We are now ready to fill in the remaining blanks on the stack: - @ - @ r2 - sp_svc - @ r3 - lr_svc - @ r4 - lr_<exception>, already fixed up for correct return/restart - @ r5 - spsr_<exception> - @ r6 - orig_r0 (see pt_regs definition in ptrace.h) - @ - stmia r7, {r2 - r6} - -#ifdef CONFIG_TRACE_IRQFLAGS - bl trace_hardirqs_off -#endif - .endm - .align 5 __dabt_svc: svc_entry @@ -348,71 +297,8 @@ ENDPROC(__pabt_svc)
/* * User mode handlers - * - * EABI note: sp_svc is always 64-bit aligned here, so should S_FRAME_SIZE */
-#if defined(CONFIG_AEABI) && (__LINUX_ARM_ARCH__ >= 5) && (S_FRAME_SIZE & 7) -#error "sizeof(struct pt_regs) must be a multiple of 8" -#endif - - .macro usr_entry - UNWIND(.fnstart ) - UNWIND(.cantunwind ) @ don't unwind the user space - sub sp, sp, #S_FRAME_SIZE - ARM( stmib sp, {r1 - r12} ) - THUMB( stmia sp, {r0 - r12} ) - - ldmia r0, {r3 - r5} - add r0, sp, #S_PC @ here for interlock avoidance - mov r6, #-1 @ "" "" "" "" - - str r3, [sp] @ save the "real" r0 copied - @ from the exception stack - - @ - @ We are now ready to fill in the remaining blanks on the stack: - @ - @ r4 - lr_<exception>, already fixed up for correct return/restart - @ r5 - spsr_<exception> - @ r6 - orig_r0 (see pt_regs definition in ptrace.h) - @ - @ Also, separately save sp_usr and lr_usr - @ - stmia r0, {r4 - r6} - ARM( stmdb r0, {sp, lr}^ ) - THUMB( store_user_sp_lr r0, r1, S_SP - S_PC ) - - @ - @ Enable the alignment trap while in kernel mode - @ - alignment_trap r0 - - @ - @ Clear FP to mark the first stack frame - @ - zero_fp - -#ifdef CONFIG_IRQSOFF_TRACER - bl trace_hardirqs_off -#endif - .endm - - .macro kuser_cmpxchg_check -#if !defined(CONFIG_CPU_32v6K) && !defined(CONFIG_NEEDS_SYSCALL_FOR_CMPXCHG) -#ifndef CONFIG_MMU -#warning "NPTL on non MMU needs fixing" -#else - @ Make sure our user space atomic helper is restarted - @ if it was interrupted in a critical region. Here we - @ perform a quick test inline since it should be false - @ 99.9999% of the time. The rest is done out of line. - cmp r4, #TASK_SIZE - blhs kuser_cmpxchg64_fixup -#endif -#endif - .endm - .align 5 __dabt_usr: usr_entry @@ -846,6 +732,7 @@ __kuser_cmpxchg64: @ 0xffff0f60 ldmfd sp!, {r4, r5, r6, pc}
.text + .global kuser_cmpxchg64_fixup kuser_cmpxchg64_fixup: @ Called from kuser_cmpxchg_fixup. @ r4 = address of interrupted insn (must be preserved). @@ -976,58 +863,6 @@ __kuser_helper_end:
THUMB( .thumb )
-/* - * Vector stubs. - * - * This code is copied to 0xffff0200 so we can use branches in the - * vectors, rather than ldr's. Note that this code must not - * exceed 0x300 bytes. - * - * Common stub entry macro: - * Enter in IRQ mode, spsr = SVC/USR CPSR, lr = SVC/USR PC - * - * SP points to a minimal amount of processor-private memory, the address - * of which is copied into r0 for the mode specific abort handler. - */ - .macro vector_stub, name, mode, correction=0 - .align 5 - -vector_\name: - .if \correction - sub lr, lr, #\correction - .endif - - @ - @ Save r0, lr_<exception> (parent PC) and spsr_<exception> - @ (parent CPSR) - @ - stmia sp, {r0, lr} @ save r0, lr - mrs lr, spsr - str lr, [sp, #8] @ save spsr - - @ - @ Prepare for SVC32 mode. IRQs remain disabled. - @ - mrs r0, cpsr - eor r0, r0, #(\mode ^ SVC_MODE | PSR_ISETSTATE) - msr spsr_cxsf, r0 - - @ - @ the branch table must immediately follow this code - @ - and lr, lr, #0x0f - THUMB( adr r0, 1f ) - THUMB( ldr lr, [r0, lr, lsl #2] ) - mov r0, sp - ARM( ldr lr, [pc, lr, lsl #2] ) - movs pc, lr @ branch to handler in SVC mode -ENDPROC(vector_\name) - - .align 2 - @ handler addresses follow this label -1: - .endm - .globl __stubs_start __stubs_start: /* diff --git a/arch/arm/kernel/entry-header.S b/arch/arm/kernel/entry-header.S index 9a8531e..c3c09ac 100644 --- a/arch/arm/kernel/entry-header.S +++ b/arch/arm/kernel/entry-header.S @@ -73,6 +73,109 @@ msr cpsr_c, \rtemp @ switch back to the SVC mode .endm
+/* + * Vector stubs. + * + * This code is copied to 0xffff0200 so we can use branches in the + * vectors, rather than ldr's. Note that this code must not + * exceed 0x300 bytes. + * + * Common stub entry macro: + * Enter in IRQ mode, spsr = SVC/USR CPSR, lr = SVC/USR PC + * + * SP points to a minimal amount of processor-private memory, the address + * of which is copied into r0 for the mode specific abort handler. + */ + .macro vector_stub, name, mode, correction=0 + .align 5 + +vector_\name: + .if \correction + sub lr, lr, #\correction + .endif + + @ + @ Save r0, lr_<exception> (parent PC) and spsr_<exception> + @ (parent CPSR) + @ + stmia sp, {r0, lr} @ save r0, lr + mrs lr, spsr + str lr, [sp, #8] @ save spsr + + @ + @ Prepare for SVC32 mode. IRQs remain disabled. + @ + mrs r0, cpsr + eor r0, r0, #(\mode ^ SVC_MODE | PSR_ISETSTATE) + msr spsr_cxsf, r0 + + @ + @ the branch table must immediately follow this code + @ + and lr, lr, #0x0f + THUMB( adr r0, 1f ) + THUMB( ldr lr, [r0, lr, lsl #2] ) + mov r0, sp + ARM( ldr lr, [pc, lr, lsl #2] ) + movs pc, lr @ branch to handler in SVC mode +ENDPROC(vector_\name) + + .align 2 + @ handler addresses follow this label +1: + .endm + +/* + * SVC mode handlers + */ + +#if defined(CONFIG_AEABI) && (__LINUX_ARM_ARCH__ >= 5) +#define SPFIX(code...) code +#else +#define SPFIX(code...) +#endif + + .macro svc_entry, stack_hole=0 + UNWIND(.fnstart ) + UNWIND(.save {r0 - pc} ) + sub sp, sp, #(S_FRAME_SIZE + \stack_hole - 4) +#ifdef CONFIG_THUMB2_KERNEL + SPFIX( str r0, [sp] ) @ temporarily saved + SPFIX( mov r0, sp ) + SPFIX( tst r0, #4 ) @ test original stack alignment + SPFIX( ldr r0, [sp] ) @ restored +#else + SPFIX( tst sp, #4 ) +#endif + SPFIX( subeq sp, sp, #4 ) + stmia sp, {r1 - r12} + + ldmia r0, {r3 - r5} + add r7, sp, #S_SP - 4 @ here for interlock avoidance + mov r6, #-1 @ "" "" "" "" + add r2, sp, #(S_FRAME_SIZE + \stack_hole - 4) + SPFIX( addeq r2, r2, #4 ) + str r3, [sp, #-4]! @ save the "real" r0 copied + @ from the exception stack + + mov r3, lr + + @ + @ We are now ready to fill in the remaining blanks on the stack: + @ + @ r2 - sp_svc + @ r3 - lr_svc + @ r4 - lr_<exception>, already fixed up for correct return/restart + @ r5 - spsr_<exception> + @ r6 - orig_r0 (see pt_regs definition in ptrace.h) + @ + stmia r7, {r2 - r6} + +#ifdef CONFIG_TRACE_IRQFLAGS + bl trace_hardirqs_off +#endif + .endm + #ifndef CONFIG_THUMB2_KERNEL .macro svc_exit, rpsr msr spsr_cxsf, \rpsr @@ -164,6 +267,73 @@ #endif /* !CONFIG_THUMB2_KERNEL */
/* + * User mode handlers + * + * EABI note: sp_svc is always 64-bit aligned here, so should S_FRAME_SIZE + */ + +#if defined(CONFIG_AEABI) && (__LINUX_ARM_ARCH__ >= 5) && (S_FRAME_SIZE & 7) +#error "sizeof(struct pt_regs) must be a multiple of 8" +#endif + + .macro usr_entry + UNWIND(.fnstart ) + UNWIND(.cantunwind ) @ don't unwind the user space + sub sp, sp, #S_FRAME_SIZE + ARM( stmib sp, {r1 - r12} ) + THUMB( stmia sp, {r0 - r12} ) + + ldmia r0, {r3 - r5} + add r0, sp, #S_PC @ here for interlock avoidance + mov r6, #-1 @ "" "" "" "" + + str r3, [sp] @ save the "real" r0 copied + @ from the exception stack + + @ + @ We are now ready to fill in the remaining blanks on the stack: + @ + @ r4 - lr_<exception>, already fixed up for correct return/restart + @ r5 - spsr_<exception> + @ r6 - orig_r0 (see pt_regs definition in ptrace.h) + @ + @ Also, separately save sp_usr and lr_usr + @ + stmia r0, {r4 - r6} + ARM( stmdb r0, {sp, lr}^ ) + THUMB( store_user_sp_lr r0, r1, S_SP - S_PC ) + + @ + @ Enable the alignment trap while in kernel mode + @ + alignment_trap r0 + + @ + @ Clear FP to mark the first stack frame + @ + zero_fp + +#ifdef CONFIG_IRQSOFF_TRACER + bl trace_hardirqs_off +#endif + .endm + + .macro kuser_cmpxchg_check +#if !defined(CONFIG_CPU_32v6K) && !defined(CONFIG_NEEDS_SYSCALL_FOR_CMPXCHG) +#ifndef CONFIG_MMU +#warning "NPTL on non MMU needs fixing" +#else + @ Make sure our user space atomic helper is restarted + @ if it was interrupted in a critical region. Here we + @ perform a quick test inline since it should be false + @ 99.9999% of the time. The rest is done out of line. + cmp r4, #TASK_SIZE + blhs kuser_cmpxchg64_fixup +#endif +#endif + .endm + +/* * These are the registers used in the syscall handler, and allow us to * have in theory up to 7 arguments to a function - r0 to r6. *
The FIQ debugger may be used to debug situations when the kernel stuck in uninterruptable sections, e.g. the kernel infinitely loops or deadlocked in an interrupt or with interrupts disabled.
By default KGDB FIQ is disabled in runtime, but can be enabled with kgdb_fiq.enable=1 kernel command line option.
Signed-off-by: Anton Vorontsov anton.vorontsov@linaro.org --- arch/arm/Kconfig | 18 ++++++ arch/arm/include/asm/kgdb.h | 8 +++ arch/arm/kernel/Makefile | 1 + arch/arm/kernel/kgdb_fiq.c | 124 +++++++++++++++++++++++++++++++++++++++ arch/arm/kernel/kgdb_fiq_entry.S | 87 +++++++++++++++++++++++++++ 5 files changed, 238 insertions(+) create mode 100644 arch/arm/kernel/kgdb_fiq.c create mode 100644 arch/arm/kernel/kgdb_fiq_entry.S
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index ade7e92..0bfa6cf 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -177,6 +177,24 @@ config GENERIC_ISA_DMA config FIQ bool
+config ARCH_MIGHT_HAVE_KGDB_FIQ + bool + +config KGDB_FIQ + bool "KGDB/KDB FIQ debugger" + depends on KGDB_KDB && ARCH_MIGHT_HAVE_KGDB_FIQ && !THUMB2_KERNEL + select FIQ + help + The FIQ debugger may be used to debug situations when the + kernel stuck in uninterruptable sections, e.g. the kernel + infinitely loops or deadlocked in an interrupt or with + interrupts disabled. + + By default KGDB FIQ is disabled in runtime, but can be + enabled with kgdb_fiq.enable=1 kernel command line option. + + If unsure, say N. + config NEED_RET_TO_USER bool
diff --git a/arch/arm/include/asm/kgdb.h b/arch/arm/include/asm/kgdb.h index 48066ce..807e547 100644 --- a/arch/arm/include/asm/kgdb.h +++ b/arch/arm/include/asm/kgdb.h @@ -11,6 +11,8 @@ #define __ARM_KGDB_H__
#include <linux/ptrace.h> +#include <linux/linkage.h> +#include <asm/exception.h>
/* * GDB assumes that we're a user process being debugged, so @@ -47,6 +49,12 @@ static inline void arch_kgdb_breakpoint(void) extern void kgdb_handle_bus_error(void); extern int kgdb_fault_expected;
+extern char kgdb_fiq_handler; +extern char kgdb_fiq_handler_end; +asmlinkage void __exception_irq_entry kgdb_fiq_do_handle(struct pt_regs *regs); +extern int __init kgdb_register_fiq(unsigned int mach_kgdb_fiq, + void (*mach_kgdb_enable_fiq)(unsigned int irq, bool on), + bool (*mach_is_kgdb_fiq)(unsigned int irq)); #endif /* !__ASSEMBLY__ */
/* diff --git a/arch/arm/kernel/Makefile b/arch/arm/kernel/Makefile index 5bbec7b..84ff575 100644 --- a/arch/arm/kernel/Makefile +++ b/arch/arm/kernel/Makefile @@ -56,6 +56,7 @@ endif obj-$(CONFIG_OABI_COMPAT) += sys_oabi-compat.o obj-$(CONFIG_ARM_THUMBEE) += thumbee.o obj-$(CONFIG_KGDB) += kgdb.o +obj-$(CONFIG_KGDB_FIQ) += kgdb_fiq_entry.o kgdb_fiq.o obj-$(CONFIG_ARM_UNWIND) += unwind.o obj-$(CONFIG_HAVE_TCM) += tcm.o obj-$(CONFIG_OF) += devtree.o diff --git a/arch/arm/kernel/kgdb_fiq.c b/arch/arm/kernel/kgdb_fiq.c new file mode 100644 index 0000000..f3df754 --- /dev/null +++ b/arch/arm/kernel/kgdb_fiq.c @@ -0,0 +1,124 @@ +/* + * KGDB FIQ + * + * Copyright 2010 Google, Inc. + * Arve Hjønnevåg arve@android.com + * Colin Cross ccross@android.com + * Copyright 2012 Linaro Ltd. + * Anton Vorontsov anton.vorontsov@linaro.org + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 as published + * by the Free Software Foundation. + */ + +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/init.h> +#include <linux/slab.h> +#include <linux/errno.h> +#include <linux/hardirq.h> +#include <linux/atomic.h> +#include <linux/kdb.h> +#include <linux/kgdb.h> +#include <asm/fiq.h> +#include <asm/exception.h> + +static int kgdb_fiq_enabled; +module_param_named(enable, kgdb_fiq_enabled, int, 0600); +MODULE_PARM_DESC(enable, "set to 1 to enable FIQ KGDB"); + +static unsigned int kgdb_fiq; +static bool (*is_kgdb_fiq)(unsigned int irq); + +asmlinkage void __exception_irq_entry kgdb_fiq_do_handle(struct pt_regs *regs) +{ + if (!is_kgdb_fiq(kgdb_fiq)) + return; + if (!kgdb_nmi_poll_knock()) + return; + + nmi_enter(); + kgdb_handle_exception(1, 0, 0, regs); + nmi_exit(); +} + +static struct fiq_handler kgdb_fiq_desc = { + .name = "kgdb", +}; + +static long kgdb_fiq_setup_stack(void *info) +{ + struct pt_regs regs; + + regs.ARM_sp = __get_free_pages(GFP_KERNEL, THREAD_SIZE_ORDER) + + THREAD_START_SP; + WARN_ON(!regs.ARM_sp); + + set_fiq_regs(®s); + return 0; +} + +static void (*kgdb_enable_fiq)(unsigned int irq, bool on); + +/** + * kgdb_fiq_enable_nmi - Manage NMI-triggered entry to KGDB + * @on: Flag to either enable or disable an NMI + * + * This function manages NMIs that usually cause KGDB to enter. That is, not + * all NMIs should be enabled or disabled, but only those that issue + * kgdb_handle_exception(). + * + * The call counts disable requests, and thus allows to nest disables. But + * trying to enable already enabled NMI is an error. + */ +static void kgdb_fiq_enable_nmi(bool on) +{ + static atomic_t cnt; + int ret; + + ret = atomic_add_return(on ? 1 : -1, &cnt); + if (ret > 1 && on) { + /* + * There should be only one instance that calls this function + * in "enable, disable" order. All other users must call + * disable first, then enable. If not, something is wrong. + */ + WARN_ON(1); + return; + } + + kgdb_enable_fiq(kgdb_fiq, ret > 0); +} + +int __init kgdb_register_fiq(unsigned int mach_kgdb_fiq, + void (*mach_kgdb_enable_fiq)(unsigned int irq, bool on), + bool (*mach_is_kgdb_fiq)(unsigned int irq)) +{ + int err; + int cpu; + + if (!kgdb_fiq_enabled) + return -ENODEV; + if (kgdb_fiq) + return -EBUSY; + + kgdb_fiq = mach_kgdb_fiq; + kgdb_enable_fiq = mach_kgdb_enable_fiq; + is_kgdb_fiq = mach_is_kgdb_fiq; + + err = claim_fiq(&kgdb_fiq_desc); + if (err) { + pr_warn("%s: unable to claim fiq", __func__); + return err; + } + + for_each_possible_cpu(cpu) + work_on_cpu(cpu, kgdb_fiq_setup_stack, NULL); + + set_fiq_handler(&kgdb_fiq_handler, + &kgdb_fiq_handler_end - &kgdb_fiq_handler); + + arch_kgdb_ops.enable_nmi = kgdb_fiq_enable_nmi; + return 0; +} diff --git a/arch/arm/kernel/kgdb_fiq_entry.S b/arch/arm/kernel/kgdb_fiq_entry.S new file mode 100644 index 0000000..d6becca --- /dev/null +++ b/arch/arm/kernel/kgdb_fiq_entry.S @@ -0,0 +1,87 @@ +/* + * KGDB FIQ entry + * + * Copyright 1996,1997,1998 Russell King. + * Copyright 2012 Linaro Ltd. + * Anton Vorontsov anton.vorontsov@linaro.org + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 as published + * by the Free Software Foundation. + */ + +#include <linux/linkage.h> +#include <asm/assembler.h> +#include <asm/memory.h> +#include <asm/unwind.h> +#include "entry-header.S" + + .text + +@ This is needed for usr_entry/alignment_trap +.LCcralign: + .long cr_alignment +.LCdohandle: + .long kgdb_fiq_do_handle + + .macro fiq_handler + ldr r1, =.LCdohandle + mov r0, sp + adr lr, BSYM(9997f) + ldr pc, [r1] +9997: + .endm + + .align 5 +__fiq_svc: + svc_entry + fiq_handler + mov r0, sp + ldmib r0, {r1 - r14} + msr cpsr_c, #FIQ_MODE | PSR_I_BIT | PSR_F_BIT + add r8, r0, #S_PC + ldr r9, [r0, #S_PSR] + msr spsr_cxsf, r9 + ldr r0, [r0, #S_R0] + ldmia r8, {pc}^ + + UNWIND(.fnend ) +ENDPROC(__fiq_svc) + .ltorg + + .align 5 +__fiq_usr: + usr_entry + kuser_cmpxchg_check + fiq_handler + get_thread_info tsk + mov why, #0 + b ret_to_user_from_irq + UNWIND(.fnend ) +ENDPROC(__fiq_usr) + .ltorg + + .global kgdb_fiq_handler +kgdb_fiq_handler: + + vector_stub fiq, FIQ_MODE, 4 + + .long __fiq_usr @ 0 (USR_26 / USR_32) + .long __fiq_svc @ 1 (FIQ_26 / FIQ_32) + .long __fiq_svc @ 2 (IRQ_26 / IRQ_32) + .long __fiq_svc @ 3 (SVC_26 / SVC_32) + .long __fiq_svc @ 4 + .long __fiq_svc @ 5 + .long __fiq_svc @ 6 + .long __fiq_svc @ 7 + .long __fiq_svc @ 8 + .long __fiq_svc @ 9 + .long __fiq_svc @ a + .long __fiq_svc @ b + .long __fiq_svc @ c + .long __fiq_svc @ d + .long __fiq_svc @ e + .long __fiq_svc @ f + + .global kgdb_fiq_handler_end +kgdb_fiq_handler_end:
Just a couple of calls to manage VIC FIQ routing. We'll use them for KGDB FIQ support on ARM Versatile machines.
Signed-off-by: Anton Vorontsov anton.vorontsov@linaro.org --- arch/arm/common/vic.c | 28 ++++++++++++++++++++++++++++ arch/arm/include/asm/hardware/vic.h | 2 ++ 2 files changed, 30 insertions(+)
diff --git a/arch/arm/common/vic.c b/arch/arm/common/vic.c index e0d5388..df2fc82 100644 --- a/arch/arm/common/vic.c +++ b/arch/arm/common/vic.c @@ -66,6 +66,34 @@ static struct vic_device vic_devices[CONFIG_ARM_VIC_NR];
static int vic_id;
+static void __iomem *vic_base(struct irq_data *d) +{ + return (void __iomem *)irq_data_get_irq_chip_data(d); +} + +void vic_fiq_select(unsigned int irq, bool on) +{ + void __iomem *base = vic_base(&irq_to_desc(irq)->irq_data); + void __iomem *sel = base + VIC_INT_SELECT; + u32 msk = 1 << irq; + u32 val; + + pr_debug("rerouting VIC vector %d to %s\n", irq, on ? "FIQ" : "IRQ"); + + val = readl(sel); + val &= ~msk; + if (on) + val |= msk; + writel(val, sel); +} + +bool vic_is_fiq_rised(unsigned int irq) +{ + void __iomem *base = vic_base(&irq_to_desc(irq)->irq_data); + + return readl(base + VIC_FIQ_STATUS) & (1 << irq); +} + /** * vic_init2 - common initialisation code * @base: Base of the VIC. diff --git a/arch/arm/include/asm/hardware/vic.h b/arch/arm/include/asm/hardware/vic.h index e14af1a..2728975 100644 --- a/arch/arm/include/asm/hardware/vic.h +++ b/arch/arm/include/asm/hardware/vic.h @@ -52,6 +52,8 @@ void __vic_init(void __iomem *base, unsigned int irq_start, u32 vic_sources, void vic_init(void __iomem *base, unsigned int irq_start, u32 vic_sources, u32 resume_sources); int vic_of_init(struct device_node *node, struct device_node *parent); void vic_handle_irq(struct pt_regs *regs); +void vic_fiq_select(unsigned int irq, bool on); +bool vic_is_fiq_rised(unsigned int irq);
#endif /* __ASSEMBLY__ */ #endif
If enabled, kernel will able to enter KGDB upon serial line activity on UART ports.
Note that even with this patch and CONFIG_KGDB_FIQ is enabled, you still need to pass kgdb_fiq.enable=1 kernel command line option, otherwise UART will behave in a normal way.
By default UART0 is used, but this can be changed via kgdb_fiq.uart_num kernel command line option.
Signed-off-by: Anton Vorontsov anton.vorontsov@linaro.org --- arch/arm/Kconfig | 1 + arch/arm/mach-versatile/Makefile | 1 + arch/arm/mach-versatile/kgdb_fiq.c | 31 +++++++++++++++++++++++++++++++ 3 files changed, 33 insertions(+) create mode 100644 arch/arm/mach-versatile/kgdb_fiq.c
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index 0bfa6cf..a94d9c5 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -337,6 +337,7 @@ config ARCH_VERSATILE select PLAT_VERSATILE_CLCD select PLAT_VERSATILE_CLOCK select PLAT_VERSATILE_FPGA_IRQ + select ARCH_MIGHT_HAVE_KGDB_FIQ help This enables support for ARM Ltd Versatile board.
diff --git a/arch/arm/mach-versatile/Makefile b/arch/arm/mach-versatile/Makefile index 81fa3fe..bfd761f 100644 --- a/arch/arm/mach-versatile/Makefile +++ b/arch/arm/mach-versatile/Makefile @@ -7,3 +7,4 @@ obj-$(CONFIG_ARCH_VERSATILE_PB) += versatile_pb.o obj-$(CONFIG_MACH_VERSATILE_AB) += versatile_ab.o obj-$(CONFIG_MACH_VERSATILE_DT) += versatile_dt.o obj-$(CONFIG_PCI) += pci.o +obj-$(CONFIG_KGDB_FIQ) += kgdb_fiq.o diff --git a/arch/arm/mach-versatile/kgdb_fiq.c b/arch/arm/mach-versatile/kgdb_fiq.c new file mode 100644 index 0000000..3cdf71d --- /dev/null +++ b/arch/arm/mach-versatile/kgdb_fiq.c @@ -0,0 +1,31 @@ +/* + * KGDB FIQ board support + * + * Copyright 2012 Linaro Ltd. + * Anton Vorontsov anton.vorontsov@linaro.org + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 as published + * by the Free Software Foundation. + */ + +#include <linux/module.h> +#include <linux/init.h> +#include <linux/kgdb.h> +#include <mach/hardware.h> +#include <mach/platform.h> +#include <asm/hardware/vic.h> + +static int kgdb_fiq; +module_param_named(uart_num, kgdb_fiq, int, 0600); +MODULE_PARM_DESC(uart_num, "UART<number> port to use for KGDB FIQ"); + +static int __init kgdb_fiq_init(void) +{ + WARN_ON(kgdb_fiq > INT_UARTINT2 - INT_UARTINT0); + + return kgdb_register_fiq(INT_UARTINT0 + kgdb_fiq, + vic_fiq_select, + vic_is_fiq_rised); +} +console_initcall(kgdb_fiq_init);
Just move the macros into header file as we would want to use them for KGDB FIQ entry code.
The following macros were moved:
- svc_entry - usr_entry - kuser_cmpxchg_check - vector_stub
To make kuser_cmpxchg_check actually work across different files, we also have to make kuser_cmpxchg64_fixup global.
Signed-off-by: Anton Vorontsov anton.vorontsov@linaro.org --- arch/arm/kernel/entry-armv.S | 167 +--------------------------------------- arch/arm/kernel/entry-header.S | 170 +++++++++++++++++++++++++++++++++++++++++ 2 files changed, 171 insertions(+), 166 deletions(-)
diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S index 0f82098..0f15368 100644 --- a/arch/arm/kernel/entry-armv.S +++ b/arch/arm/kernel/entry-armv.S @@ -136,57 +136,6 @@ common_invalid: b bad_mode ENDPROC(__und_invalid)
-/* - * SVC mode handlers - */ - -#if defined(CONFIG_AEABI) && (__LINUX_ARM_ARCH__ >= 5) -#define SPFIX(code...) code -#else -#define SPFIX(code...) -#endif - - .macro svc_entry, stack_hole=0 - UNWIND(.fnstart ) - UNWIND(.save {r0 - pc} ) - sub sp, sp, #(S_FRAME_SIZE + \stack_hole - 4) -#ifdef CONFIG_THUMB2_KERNEL - SPFIX( str r0, [sp] ) @ temporarily saved - SPFIX( mov r0, sp ) - SPFIX( tst r0, #4 ) @ test original stack alignment - SPFIX( ldr r0, [sp] ) @ restored -#else - SPFIX( tst sp, #4 ) -#endif - SPFIX( subeq sp, sp, #4 ) - stmia sp, {r1 - r12} - - ldmia r0, {r3 - r5} - add r7, sp, #S_SP - 4 @ here for interlock avoidance - mov r6, #-1 @ "" "" "" "" - add r2, sp, #(S_FRAME_SIZE + \stack_hole - 4) - SPFIX( addeq r2, r2, #4 ) - str r3, [sp, #-4]! @ save the "real" r0 copied - @ from the exception stack - - mov r3, lr - - @ - @ We are now ready to fill in the remaining blanks on the stack: - @ - @ r2 - sp_svc - @ r3 - lr_svc - @ r4 - lr_<exception>, already fixed up for correct return/restart - @ r5 - spsr_<exception> - @ r6 - orig_r0 (see pt_regs definition in ptrace.h) - @ - stmia r7, {r2 - r6} - -#ifdef CONFIG_TRACE_IRQFLAGS - bl trace_hardirqs_off -#endif - .endm - .align 5 __dabt_svc: svc_entry @@ -348,71 +297,8 @@ ENDPROC(__pabt_svc)
/* * User mode handlers - * - * EABI note: sp_svc is always 64-bit aligned here, so should S_FRAME_SIZE */
-#if defined(CONFIG_AEABI) && (__LINUX_ARM_ARCH__ >= 5) && (S_FRAME_SIZE & 7) -#error "sizeof(struct pt_regs) must be a multiple of 8" -#endif - - .macro usr_entry - UNWIND(.fnstart ) - UNWIND(.cantunwind ) @ don't unwind the user space - sub sp, sp, #S_FRAME_SIZE - ARM( stmib sp, {r1 - r12} ) - THUMB( stmia sp, {r0 - r12} ) - - ldmia r0, {r3 - r5} - add r0, sp, #S_PC @ here for interlock avoidance - mov r6, #-1 @ "" "" "" "" - - str r3, [sp] @ save the "real" r0 copied - @ from the exception stack - - @ - @ We are now ready to fill in the remaining blanks on the stack: - @ - @ r4 - lr_<exception>, already fixed up for correct return/restart - @ r5 - spsr_<exception> - @ r6 - orig_r0 (see pt_regs definition in ptrace.h) - @ - @ Also, separately save sp_usr and lr_usr - @ - stmia r0, {r4 - r6} - ARM( stmdb r0, {sp, lr}^ ) - THUMB( store_user_sp_lr r0, r1, S_SP - S_PC ) - - @ - @ Enable the alignment trap while in kernel mode - @ - alignment_trap r0 - - @ - @ Clear FP to mark the first stack frame - @ - zero_fp - -#ifdef CONFIG_IRQSOFF_TRACER - bl trace_hardirqs_off -#endif - .endm - - .macro kuser_cmpxchg_check -#if !defined(CONFIG_CPU_32v6K) && !defined(CONFIG_NEEDS_SYSCALL_FOR_CMPXCHG) -#ifndef CONFIG_MMU -#warning "NPTL on non MMU needs fixing" -#else - @ Make sure our user space atomic helper is restarted - @ if it was interrupted in a critical region. Here we - @ perform a quick test inline since it should be false - @ 99.9999% of the time. The rest is done out of line. - cmp r4, #TASK_SIZE - blhs kuser_cmpxchg64_fixup -#endif -#endif - .endm - .align 5 __dabt_usr: usr_entry @@ -846,6 +732,7 @@ __kuser_cmpxchg64: @ 0xffff0f60 ldmfd sp!, {r4, r5, r6, pc}
.text + .global kuser_cmpxchg64_fixup kuser_cmpxchg64_fixup: @ Called from kuser_cmpxchg_fixup. @ r4 = address of interrupted insn (must be preserved). @@ -976,58 +863,6 @@ __kuser_helper_end:
THUMB( .thumb )
-/* - * Vector stubs. - * - * This code is copied to 0xffff0200 so we can use branches in the - * vectors, rather than ldr's. Note that this code must not - * exceed 0x300 bytes. - * - * Common stub entry macro: - * Enter in IRQ mode, spsr = SVC/USR CPSR, lr = SVC/USR PC - * - * SP points to a minimal amount of processor-private memory, the address - * of which is copied into r0 for the mode specific abort handler. - */ - .macro vector_stub, name, mode, correction=0 - .align 5 - -vector_\name: - .if \correction - sub lr, lr, #\correction - .endif - - @ - @ Save r0, lr_<exception> (parent PC) and spsr_<exception> - @ (parent CPSR) - @ - stmia sp, {r0, lr} @ save r0, lr - mrs lr, spsr - str lr, [sp, #8] @ save spsr - - @ - @ Prepare for SVC32 mode. IRQs remain disabled. - @ - mrs r0, cpsr - eor r0, r0, #(\mode ^ SVC_MODE | PSR_ISETSTATE) - msr spsr_cxsf, r0 - - @ - @ the branch table must immediately follow this code - @ - and lr, lr, #0x0f - THUMB( adr r0, 1f ) - THUMB( ldr lr, [r0, lr, lsl #2] ) - mov r0, sp - ARM( ldr lr, [pc, lr, lsl #2] ) - movs pc, lr @ branch to handler in SVC mode -ENDPROC(vector_\name) - - .align 2 - @ handler addresses follow this label -1: - .endm - .globl __stubs_start __stubs_start: /* diff --git a/arch/arm/kernel/entry-header.S b/arch/arm/kernel/entry-header.S index 9a8531e..c3c09ac 100644 --- a/arch/arm/kernel/entry-header.S +++ b/arch/arm/kernel/entry-header.S @@ -73,6 +73,109 @@ msr cpsr_c, \rtemp @ switch back to the SVC mode .endm
+/* + * Vector stubs. + * + * This code is copied to 0xffff0200 so we can use branches in the + * vectors, rather than ldr's. Note that this code must not + * exceed 0x300 bytes. + * + * Common stub entry macro: + * Enter in IRQ mode, spsr = SVC/USR CPSR, lr = SVC/USR PC + * + * SP points to a minimal amount of processor-private memory, the address + * of which is copied into r0 for the mode specific abort handler. + */ + .macro vector_stub, name, mode, correction=0 + .align 5 + +vector_\name: + .if \correction + sub lr, lr, #\correction + .endif + + @ + @ Save r0, lr_<exception> (parent PC) and spsr_<exception> + @ (parent CPSR) + @ + stmia sp, {r0, lr} @ save r0, lr + mrs lr, spsr + str lr, [sp, #8] @ save spsr + + @ + @ Prepare for SVC32 mode. IRQs remain disabled. + @ + mrs r0, cpsr + eor r0, r0, #(\mode ^ SVC_MODE | PSR_ISETSTATE) + msr spsr_cxsf, r0 + + @ + @ the branch table must immediately follow this code + @ + and lr, lr, #0x0f + THUMB( adr r0, 1f ) + THUMB( ldr lr, [r0, lr, lsl #2] ) + mov r0, sp + ARM( ldr lr, [pc, lr, lsl #2] ) + movs pc, lr @ branch to handler in SVC mode +ENDPROC(vector_\name) + + .align 2 + @ handler addresses follow this label +1: + .endm + +/* + * SVC mode handlers + */ + +#if defined(CONFIG_AEABI) && (__LINUX_ARM_ARCH__ >= 5) +#define SPFIX(code...) code +#else +#define SPFIX(code...) +#endif + + .macro svc_entry, stack_hole=0 + UNWIND(.fnstart ) + UNWIND(.save {r0 - pc} ) + sub sp, sp, #(S_FRAME_SIZE + \stack_hole - 4) +#ifdef CONFIG_THUMB2_KERNEL + SPFIX( str r0, [sp] ) @ temporarily saved + SPFIX( mov r0, sp ) + SPFIX( tst r0, #4 ) @ test original stack alignment + SPFIX( ldr r0, [sp] ) @ restored +#else + SPFIX( tst sp, #4 ) +#endif + SPFIX( subeq sp, sp, #4 ) + stmia sp, {r1 - r12} + + ldmia r0, {r3 - r5} + add r7, sp, #S_SP - 4 @ here for interlock avoidance + mov r6, #-1 @ "" "" "" "" + add r2, sp, #(S_FRAME_SIZE + \stack_hole - 4) + SPFIX( addeq r2, r2, #4 ) + str r3, [sp, #-4]! @ save the "real" r0 copied + @ from the exception stack + + mov r3, lr + + @ + @ We are now ready to fill in the remaining blanks on the stack: + @ + @ r2 - sp_svc + @ r3 - lr_svc + @ r4 - lr_<exception>, already fixed up for correct return/restart + @ r5 - spsr_<exception> + @ r6 - orig_r0 (see pt_regs definition in ptrace.h) + @ + stmia r7, {r2 - r6} + +#ifdef CONFIG_TRACE_IRQFLAGS + bl trace_hardirqs_off +#endif + .endm + #ifndef CONFIG_THUMB2_KERNEL .macro svc_exit, rpsr msr spsr_cxsf, \rpsr @@ -164,6 +267,73 @@ #endif /* !CONFIG_THUMB2_KERNEL */
/* + * User mode handlers + * + * EABI note: sp_svc is always 64-bit aligned here, so should S_FRAME_SIZE + */ + +#if defined(CONFIG_AEABI) && (__LINUX_ARM_ARCH__ >= 5) && (S_FRAME_SIZE & 7) +#error "sizeof(struct pt_regs) must be a multiple of 8" +#endif + + .macro usr_entry + UNWIND(.fnstart ) + UNWIND(.cantunwind ) @ don't unwind the user space + sub sp, sp, #S_FRAME_SIZE + ARM( stmib sp, {r1 - r12} ) + THUMB( stmia sp, {r0 - r12} ) + + ldmia r0, {r3 - r5} + add r0, sp, #S_PC @ here for interlock avoidance + mov r6, #-1 @ "" "" "" "" + + str r3, [sp] @ save the "real" r0 copied + @ from the exception stack + + @ + @ We are now ready to fill in the remaining blanks on the stack: + @ + @ r4 - lr_<exception>, already fixed up for correct return/restart + @ r5 - spsr_<exception> + @ r6 - orig_r0 (see pt_regs definition in ptrace.h) + @ + @ Also, separately save sp_usr and lr_usr + @ + stmia r0, {r4 - r6} + ARM( stmdb r0, {sp, lr}^ ) + THUMB( store_user_sp_lr r0, r1, S_SP - S_PC ) + + @ + @ Enable the alignment trap while in kernel mode + @ + alignment_trap r0 + + @ + @ Clear FP to mark the first stack frame + @ + zero_fp + +#ifdef CONFIG_IRQSOFF_TRACER + bl trace_hardirqs_off +#endif + .endm + + .macro kuser_cmpxchg_check +#if !defined(CONFIG_CPU_32v6K) && !defined(CONFIG_NEEDS_SYSCALL_FOR_CMPXCHG) +#ifndef CONFIG_MMU +#warning "NPTL on non MMU needs fixing" +#else + @ Make sure our user space atomic helper is restarted + @ if it was interrupted in a critical region. Here we + @ perform a quick test inline since it should be false + @ 99.9999% of the time. The rest is done out of line. + cmp r4, #TASK_SIZE + blhs kuser_cmpxchg64_fixup +#endif +#endif + .endm + +/* * These are the registers used in the syscall handler, and allow us to * have in theory up to 7 arguments to a function - r0 to r6. *
The FIQ debugger may be used to debug situations when the kernel stuck in uninterruptable sections, e.g. the kernel infinitely loops or deadlocked in an interrupt or with interrupts disabled.
By default KGDB FIQ is disabled in runtime, but can be enabled with kgdb_fiq.enable=1 kernel command line option.
Signed-off-by: Anton Vorontsov anton.vorontsov@linaro.org --- arch/arm/Kconfig | 18 ++++++ arch/arm/include/asm/kgdb.h | 8 +++ arch/arm/kernel/Makefile | 1 + arch/arm/kernel/kgdb_fiq.c | 124 +++++++++++++++++++++++++++++++++++++++ arch/arm/kernel/kgdb_fiq_entry.S | 87 +++++++++++++++++++++++++++ 5 files changed, 238 insertions(+) create mode 100644 arch/arm/kernel/kgdb_fiq.c create mode 100644 arch/arm/kernel/kgdb_fiq_entry.S
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index ade7e92..0bfa6cf 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -177,6 +177,24 @@ config GENERIC_ISA_DMA config FIQ bool
+config ARCH_MIGHT_HAVE_KGDB_FIQ + bool + +config KGDB_FIQ + bool "KGDB/KDB FIQ debugger" + depends on KGDB_KDB && ARCH_MIGHT_HAVE_KGDB_FIQ && !THUMB2_KERNEL + select FIQ + help + The FIQ debugger may be used to debug situations when the + kernel stuck in uninterruptable sections, e.g. the kernel + infinitely loops or deadlocked in an interrupt or with + interrupts disabled. + + By default KGDB FIQ is disabled in runtime, but can be + enabled with kgdb_fiq.enable=1 kernel command line option. + + If unsure, say N. + config NEED_RET_TO_USER bool
diff --git a/arch/arm/include/asm/kgdb.h b/arch/arm/include/asm/kgdb.h index 48066ce..807e547 100644 --- a/arch/arm/include/asm/kgdb.h +++ b/arch/arm/include/asm/kgdb.h @@ -11,6 +11,8 @@ #define __ARM_KGDB_H__
#include <linux/ptrace.h> +#include <linux/linkage.h> +#include <asm/exception.h>
/* * GDB assumes that we're a user process being debugged, so @@ -47,6 +49,12 @@ static inline void arch_kgdb_breakpoint(void) extern void kgdb_handle_bus_error(void); extern int kgdb_fault_expected;
+extern char kgdb_fiq_handler; +extern char kgdb_fiq_handler_end; +asmlinkage void __exception_irq_entry kgdb_fiq_do_handle(struct pt_regs *regs); +extern int __init kgdb_register_fiq(unsigned int mach_kgdb_fiq, + void (*mach_kgdb_enable_fiq)(unsigned int irq, bool on), + bool (*mach_is_kgdb_fiq)(unsigned int irq)); #endif /* !__ASSEMBLY__ */
/* diff --git a/arch/arm/kernel/Makefile b/arch/arm/kernel/Makefile index 5bbec7b..84ff575 100644 --- a/arch/arm/kernel/Makefile +++ b/arch/arm/kernel/Makefile @@ -56,6 +56,7 @@ endif obj-$(CONFIG_OABI_COMPAT) += sys_oabi-compat.o obj-$(CONFIG_ARM_THUMBEE) += thumbee.o obj-$(CONFIG_KGDB) += kgdb.o +obj-$(CONFIG_KGDB_FIQ) += kgdb_fiq_entry.o kgdb_fiq.o obj-$(CONFIG_ARM_UNWIND) += unwind.o obj-$(CONFIG_HAVE_TCM) += tcm.o obj-$(CONFIG_OF) += devtree.o diff --git a/arch/arm/kernel/kgdb_fiq.c b/arch/arm/kernel/kgdb_fiq.c new file mode 100644 index 0000000..f3df754 --- /dev/null +++ b/arch/arm/kernel/kgdb_fiq.c @@ -0,0 +1,124 @@ +/* + * KGDB FIQ + * + * Copyright 2010 Google, Inc. + * Arve Hjønnevåg arve@android.com + * Colin Cross ccross@android.com + * Copyright 2012 Linaro Ltd. + * Anton Vorontsov anton.vorontsov@linaro.org + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 as published + * by the Free Software Foundation. + */ + +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/init.h> +#include <linux/slab.h> +#include <linux/errno.h> +#include <linux/hardirq.h> +#include <linux/atomic.h> +#include <linux/kdb.h> +#include <linux/kgdb.h> +#include <asm/fiq.h> +#include <asm/exception.h> + +static int kgdb_fiq_enabled; +module_param_named(enable, kgdb_fiq_enabled, int, 0600); +MODULE_PARM_DESC(enable, "set to 1 to enable FIQ KGDB"); + +static unsigned int kgdb_fiq; +static bool (*is_kgdb_fiq)(unsigned int irq); + +asmlinkage void __exception_irq_entry kgdb_fiq_do_handle(struct pt_regs *regs) +{ + if (!is_kgdb_fiq(kgdb_fiq)) + return; + if (!kgdb_nmi_poll_knock()) + return; + + nmi_enter(); + kgdb_handle_exception(1, 0, 0, regs); + nmi_exit(); +} + +static struct fiq_handler kgdb_fiq_desc = { + .name = "kgdb", +}; + +static long kgdb_fiq_setup_stack(void *info) +{ + struct pt_regs regs; + + regs.ARM_sp = __get_free_pages(GFP_KERNEL, THREAD_SIZE_ORDER) + + THREAD_START_SP; + WARN_ON(!regs.ARM_sp); + + set_fiq_regs(®s); + return 0; +} + +static void (*kgdb_enable_fiq)(unsigned int irq, bool on); + +/** + * kgdb_fiq_enable_nmi - Manage NMI-triggered entry to KGDB + * @on: Flag to either enable or disable an NMI + * + * This function manages NMIs that usually cause KGDB to enter. That is, not + * all NMIs should be enabled or disabled, but only those that issue + * kgdb_handle_exception(). + * + * The call counts disable requests, and thus allows to nest disables. But + * trying to enable already enabled NMI is an error. + */ +static void kgdb_fiq_enable_nmi(bool on) +{ + static atomic_t cnt; + int ret; + + ret = atomic_add_return(on ? 1 : -1, &cnt); + if (ret > 1 && on) { + /* + * There should be only one instance that calls this function + * in "enable, disable" order. All other users must call + * disable first, then enable. If not, something is wrong. + */ + WARN_ON(1); + return; + } + + kgdb_enable_fiq(kgdb_fiq, ret > 0); +} + +int __init kgdb_register_fiq(unsigned int mach_kgdb_fiq, + void (*mach_kgdb_enable_fiq)(unsigned int irq, bool on), + bool (*mach_is_kgdb_fiq)(unsigned int irq)) +{ + int err; + int cpu; + + if (!kgdb_fiq_enabled) + return -ENODEV; + if (kgdb_fiq) + return -EBUSY; + + kgdb_fiq = mach_kgdb_fiq; + kgdb_enable_fiq = mach_kgdb_enable_fiq; + is_kgdb_fiq = mach_is_kgdb_fiq; + + err = claim_fiq(&kgdb_fiq_desc); + if (err) { + pr_warn("%s: unable to claim fiq", __func__); + return err; + } + + for_each_possible_cpu(cpu) + work_on_cpu(cpu, kgdb_fiq_setup_stack, NULL); + + set_fiq_handler(&kgdb_fiq_handler, + &kgdb_fiq_handler_end - &kgdb_fiq_handler); + + arch_kgdb_ops.enable_nmi = kgdb_fiq_enable_nmi; + return 0; +} diff --git a/arch/arm/kernel/kgdb_fiq_entry.S b/arch/arm/kernel/kgdb_fiq_entry.S new file mode 100644 index 0000000..d6becca --- /dev/null +++ b/arch/arm/kernel/kgdb_fiq_entry.S @@ -0,0 +1,87 @@ +/* + * KGDB FIQ entry + * + * Copyright 1996,1997,1998 Russell King. + * Copyright 2012 Linaro Ltd. + * Anton Vorontsov anton.vorontsov@linaro.org + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 as published + * by the Free Software Foundation. + */ + +#include <linux/linkage.h> +#include <asm/assembler.h> +#include <asm/memory.h> +#include <asm/unwind.h> +#include "entry-header.S" + + .text + +@ This is needed for usr_entry/alignment_trap +.LCcralign: + .long cr_alignment +.LCdohandle: + .long kgdb_fiq_do_handle + + .macro fiq_handler + ldr r1, =.LCdohandle + mov r0, sp + adr lr, BSYM(9997f) + ldr pc, [r1] +9997: + .endm + + .align 5 +__fiq_svc: + svc_entry + fiq_handler + mov r0, sp + ldmib r0, {r1 - r14} + msr cpsr_c, #FIQ_MODE | PSR_I_BIT | PSR_F_BIT + add r8, r0, #S_PC + ldr r9, [r0, #S_PSR] + msr spsr_cxsf, r9 + ldr r0, [r0, #S_R0] + ldmia r8, {pc}^ + + UNWIND(.fnend ) +ENDPROC(__fiq_svc) + .ltorg + + .align 5 +__fiq_usr: + usr_entry + kuser_cmpxchg_check + fiq_handler + get_thread_info tsk + mov why, #0 + b ret_to_user_from_irq + UNWIND(.fnend ) +ENDPROC(__fiq_usr) + .ltorg + + .global kgdb_fiq_handler +kgdb_fiq_handler: + + vector_stub fiq, FIQ_MODE, 4 + + .long __fiq_usr @ 0 (USR_26 / USR_32) + .long __fiq_svc @ 1 (FIQ_26 / FIQ_32) + .long __fiq_svc @ 2 (IRQ_26 / IRQ_32) + .long __fiq_svc @ 3 (SVC_26 / SVC_32) + .long __fiq_svc @ 4 + .long __fiq_svc @ 5 + .long __fiq_svc @ 6 + .long __fiq_svc @ 7 + .long __fiq_svc @ 8 + .long __fiq_svc @ 9 + .long __fiq_svc @ a + .long __fiq_svc @ b + .long __fiq_svc @ c + .long __fiq_svc @ d + .long __fiq_svc @ e + .long __fiq_svc @ f + + .global kgdb_fiq_handler_end +kgdb_fiq_handler_end:
Just a couple of calls to manage VIC FIQ routing. We'll use them for KGDB FIQ support on ARM Versatile machines.
Signed-off-by: Anton Vorontsov anton.vorontsov@linaro.org --- arch/arm/common/vic.c | 28 ++++++++++++++++++++++++++++ arch/arm/include/asm/hardware/vic.h | 2 ++ 2 files changed, 30 insertions(+)
diff --git a/arch/arm/common/vic.c b/arch/arm/common/vic.c index e0d5388..df2fc82 100644 --- a/arch/arm/common/vic.c +++ b/arch/arm/common/vic.c @@ -66,6 +66,34 @@ static struct vic_device vic_devices[CONFIG_ARM_VIC_NR];
static int vic_id;
+static void __iomem *vic_base(struct irq_data *d) +{ + return (void __iomem *)irq_data_get_irq_chip_data(d); +} + +void vic_fiq_select(unsigned int irq, bool on) +{ + void __iomem *base = vic_base(&irq_to_desc(irq)->irq_data); + void __iomem *sel = base + VIC_INT_SELECT; + u32 msk = 1 << irq; + u32 val; + + pr_debug("rerouting VIC vector %d to %s\n", irq, on ? "FIQ" : "IRQ"); + + val = readl(sel); + val &= ~msk; + if (on) + val |= msk; + writel(val, sel); +} + +bool vic_is_fiq_rised(unsigned int irq) +{ + void __iomem *base = vic_base(&irq_to_desc(irq)->irq_data); + + return readl(base + VIC_FIQ_STATUS) & (1 << irq); +} + /** * vic_init2 - common initialisation code * @base: Base of the VIC. diff --git a/arch/arm/include/asm/hardware/vic.h b/arch/arm/include/asm/hardware/vic.h index e14af1a..2728975 100644 --- a/arch/arm/include/asm/hardware/vic.h +++ b/arch/arm/include/asm/hardware/vic.h @@ -52,6 +52,8 @@ void __vic_init(void __iomem *base, unsigned int irq_start, u32 vic_sources, void vic_init(void __iomem *base, unsigned int irq_start, u32 vic_sources, u32 resume_sources); int vic_of_init(struct device_node *node, struct device_node *parent); void vic_handle_irq(struct pt_regs *regs); +void vic_fiq_select(unsigned int irq, bool on); +bool vic_is_fiq_rised(unsigned int irq);
#endif /* __ASSEMBLY__ */ #endif
If enabled, kernel will able to enter KGDB upon serial line activity on UART ports.
Note that even with this patch and CONFIG_KGDB_FIQ is enabled, you still need to pass kgdb_fiq.enable=1 kernel command line option, otherwise UART will behave in a normal way.
By default UART0 is used, but this can be changed via kgdb_fiq.uart_num kernel command line option.
Signed-off-by: Anton Vorontsov anton.vorontsov@linaro.org --- arch/arm/Kconfig | 1 + arch/arm/mach-versatile/Makefile | 1 + arch/arm/mach-versatile/kgdb_fiq.c | 31 +++++++++++++++++++++++++++++++ 3 files changed, 33 insertions(+) create mode 100644 arch/arm/mach-versatile/kgdb_fiq.c
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index 0bfa6cf..a94d9c5 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -337,6 +337,7 @@ config ARCH_VERSATILE select PLAT_VERSATILE_CLCD select PLAT_VERSATILE_CLOCK select PLAT_VERSATILE_FPGA_IRQ + select ARCH_MIGHT_HAVE_KGDB_FIQ help This enables support for ARM Ltd Versatile board.
diff --git a/arch/arm/mach-versatile/Makefile b/arch/arm/mach-versatile/Makefile index 81fa3fe..bfd761f 100644 --- a/arch/arm/mach-versatile/Makefile +++ b/arch/arm/mach-versatile/Makefile @@ -7,3 +7,4 @@ obj-$(CONFIG_ARCH_VERSATILE_PB) += versatile_pb.o obj-$(CONFIG_MACH_VERSATILE_AB) += versatile_ab.o obj-$(CONFIG_MACH_VERSATILE_DT) += versatile_dt.o obj-$(CONFIG_PCI) += pci.o +obj-$(CONFIG_KGDB_FIQ) += kgdb_fiq.o diff --git a/arch/arm/mach-versatile/kgdb_fiq.c b/arch/arm/mach-versatile/kgdb_fiq.c new file mode 100644 index 0000000..3cdf71d --- /dev/null +++ b/arch/arm/mach-versatile/kgdb_fiq.c @@ -0,0 +1,31 @@ +/* + * KGDB FIQ board support + * + * Copyright 2012 Linaro Ltd. + * Anton Vorontsov anton.vorontsov@linaro.org + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 as published + * by the Free Software Foundation. + */ + +#include <linux/module.h> +#include <linux/init.h> +#include <linux/kgdb.h> +#include <mach/hardware.h> +#include <mach/platform.h> +#include <asm/hardware/vic.h> + +static int kgdb_fiq; +module_param_named(uart_num, kgdb_fiq, int, 0600); +MODULE_PARM_DESC(uart_num, "UART<number> port to use for KGDB FIQ"); + +static int __init kgdb_fiq_init(void) +{ + WARN_ON(kgdb_fiq > INT_UARTINT2 - INT_UARTINT0); + + return kgdb_register_fiq(INT_UARTINT0 + kgdb_fiq, + vic_fiq_select, + vic_is_fiq_rised); +} +console_initcall(kgdb_fiq_init);
On Thu, Nov 22, 2012 at 04:29:57PM -0800, Anton Vorontsov wrote:
Hello Andrew, Russell,
The KDB/NMI core support has been merged into v3.7-rc1, so the only ARM bits are pending now.
I addressed all the comments ~two month ago, and since then just resending these patches. I know we're all busy, so no blaming. :) But then let's pass this via -mm?
Guys, could someone take a look at this?.. Considering the low impact of this series (it mostly adds code, and the only modification part the one that just moves things around), maybe it still has some chance to get into 3.9?
Thanks, Anton.
On Thu, Dec 06, 2012 at 07:17:26AM -0800, Anton Vorontsov wrote:
On Thu, Nov 22, 2012 at 04:29:57PM -0800, Anton Vorontsov wrote:
Hello Andrew, Russell,
The KDB/NMI core support has been merged into v3.7-rc1, so the only ARM bits are pending now.
I addressed all the comments ~two month ago, and since then just resending these patches. I know we're all busy, so no blaming. :) But then let's pass this via -mm?
Guys, could someone take a look at this?.. Considering the low impact of this series (it mostly adds code, and the only modification part the one that just moves things around), maybe it still has some chance to get into 3.9?
Oops, I mean 3.8, of course. :)
linaro-kernel@lists.linaro.org
-
Anton Vorontsov -
Anton Vorontsov