From: "David A. Long" dave.long@linaro.org

Using Rabin Vincent's ARM uprobes patches as a base, enable uprobes support on ARM.

Caveats:

- Thumb is not supported - XOL abort/trap handling is not implemented

Signed-off-by: David A. Long dave.long@linaro.org --- arch/arm/Kconfig | 4 + arch/arm/include/asm/ptrace.h | 6 + arch/arm/include/asm/thread_info.h | 5 +- arch/arm/include/asm/uprobes.h | 34 ++++++ arch/arm/kernel/Makefile | 1 + arch/arm/kernel/signal.c | 4 + arch/arm/kernel/uprobes-arm.c | 220 +++++++++++++++++++++++++++++++++++++ arch/arm/kernel/uprobes.c | 203 ++++++++++++++++++++++++++++++++++ arch/arm/kernel/uprobes.h | 25 +++++ arch/powerpc/include/asm/uprobes.h | 1 - include/linux/uprobes.h | 3 + kernel/events/uprobes.c | 1 + 12 files changed, 505 insertions(+), 2 deletions(-) create mode 100644 arch/arm/include/asm/uprobes.h create mode 100644 arch/arm/kernel/uprobes-arm.c create mode 100644 arch/arm/kernel/uprobes.c create mode 100644 arch/arm/kernel/uprobes.h

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index 2651b1d..3b17923 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -192,6 +192,10 @@ config ZONE_DMA config NEED_DMA_MAP_STATE def_bool y

+config ARCH_SUPPORTS_UPROBES + depends on KPROBES + def_bool y + config ARCH_HAS_DMA_SET_COHERENT_MASK bool

diff --git a/arch/arm/include/asm/ptrace.h b/arch/arm/include/asm/ptrace.h index 3d52ee1..c223e90 100644 --- a/arch/arm/include/asm/ptrace.h +++ b/arch/arm/include/asm/ptrace.h @@ -76,6 +76,12 @@ static inline long regs_return_value(struct pt_regs *regs)

#define instruction_pointer(regs) (regs)->ARM_pc

+static inline void instruction_pointer_set(struct pt_regs *regs, + unsigned long val) +{ + instruction_pointer(regs) = val; +} + #ifdef CONFIG_SMP extern unsigned long profile_pc(struct pt_regs *regs); #else diff --git a/arch/arm/include/asm/thread_info.h b/arch/arm/include/asm/thread_info.h index 1995d1a..a46e350 100644 --- a/arch/arm/include/asm/thread_info.h +++ b/arch/arm/include/asm/thread_info.h @@ -148,6 +148,7 @@ extern int vfp_restore_user_hwstate(struct user_vfp __user *, #define TIF_SIGPENDING 0 #define TIF_NEED_RESCHED 1 #define TIF_NOTIFY_RESUME 2 /* callback before returning to user */ +#define TIF_UPROBE 7 #define TIF_SYSCALL_TRACE 8 #define TIF_SYSCALL_AUDIT 9 #define TIF_SYSCALL_TRACEPOINT 10 @@ -161,6 +162,7 @@ extern int vfp_restore_user_hwstate(struct user_vfp __user *, #define _TIF_SIGPENDING (1 << TIF_SIGPENDING) #define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED) #define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME) +#define _TIF_UPROBE (1 << TIF_UPROBE) #define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE) #define _TIF_SYSCALL_AUDIT (1 << TIF_SYSCALL_AUDIT) #define _TIF_SYSCALL_TRACEPOINT (1 << TIF_SYSCALL_TRACEPOINT) @@ -174,7 +176,8 @@ extern int vfp_restore_user_hwstate(struct user_vfp __user *, /* * Change these and you break ASM code in entry-common.S */ -#define _TIF_WORK_MASK (_TIF_NEED_RESCHED | _TIF_SIGPENDING | _TIF_NOTIFY_RESUME) +#define _TIF_WORK_MASK (_TIF_NEED_RESCHED | _TIF_SIGPENDING | \ + _TIF_NOTIFY_RESUME | _TIF_UPROBE)

#endif /* __KERNEL__ */ #endif /* __ASM_ARM_THREAD_INFO_H */ diff --git a/arch/arm/include/asm/uprobes.h b/arch/arm/include/asm/uprobes.h new file mode 100644 index 0000000..fa4b81e --- /dev/null +++ b/arch/arm/include/asm/uprobes.h @@ -0,0 +1,34 @@ +#ifndef _ASM_UPROBES_H +#define _ASM_UPROBES_H + +#include <asm/probes.h> + +typedef u32 uprobe_opcode_t; + +#define MAX_UINSN_BYTES 4 +#define UPROBE_XOL_SLOT_BYTES 64 + +#define UPROBE_SWBP_INSN 0x07f001f9 +#define UPROBE_SS_INSN 0x07f001fa +#define UPROBE_SWBP_INSN_SIZE 4 + +struct arch_uprobe_task { + u32 backup; +}; + +struct arch_uprobe { + u8 insn[MAX_UINSN_BYTES]; + uprobe_opcode_t modinsn; + uprobe_opcode_t bpinsn; + bool simulate; + u32 pcreg; + void (*prehandler)(struct arch_uprobe *auprobe, + struct arch_uprobe_task *autask, + struct pt_regs *regs); + void (*posthandler)(struct arch_uprobe *auprobe, + struct arch_uprobe_task *autask, + struct pt_regs *regs); + struct arch_specific_insn asi; +}; + +#endif diff --git a/arch/arm/kernel/Makefile b/arch/arm/kernel/Makefile index 9053be4..855d82c 100644 --- a/arch/arm/kernel/Makefile +++ b/arch/arm/kernel/Makefile @@ -40,6 +40,7 @@ obj-$(CONFIG_DYNAMIC_FTRACE) += ftrace.o insn.o obj-$(CONFIG_FUNCTION_GRAPH_TRACER) += ftrace.o insn.o obj-$(CONFIG_JUMP_LABEL) += jump_label.o insn.o patch.o obj-$(CONFIG_KEXEC) += machine_kexec.o relocate_kernel.o +obj-$(CONFIG_UPROBES) += probes.o uprobes.o uprobes-arm.o kprobes-arm.o obj-$(CONFIG_KPROBES) += probes.o kprobes.o kprobes-common.o patch.o ifdef CONFIG_THUMB2_KERNEL obj-$(CONFIG_KPROBES) += kprobes-thumb.o diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c index 296786b..7d9d2cd 100644 --- a/arch/arm/kernel/signal.c +++ b/arch/arm/kernel/signal.c @@ -12,6 +12,7 @@ #include <linux/personality.h> #include <linux/uaccess.h> #include <linux/tracehook.h> +#include <linux/uprobes.h>

#include <asm/elf.h> #include <asm/cacheflush.h> @@ -593,6 +594,9 @@ do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall) return restart; } syscall = 0; + } else if (thread_flags & _TIF_UPROBE) { + clear_thread_flag(TIF_UPROBE); + uprobe_notify_resume(regs); } else { clear_thread_flag(TIF_NOTIFY_RESUME); tracehook_notify_resume(regs); diff --git a/arch/arm/kernel/uprobes-arm.c b/arch/arm/kernel/uprobes-arm.c new file mode 100644 index 0000000..f43d0c5 --- /dev/null +++ b/arch/arm/kernel/uprobes-arm.c @@ -0,0 +1,220 @@ +#include <linux/kernel.h> +#include <linux/kprobes.h> +#include <linux/uprobes.h> +#include <linux/module.h> + +#include "kprobes.h" +#include "uprobes.h" +#include "probes-arm.h" + +static int uprobes_substitute_pc(kprobe_opcode_t *pinsn, u32 oregs) +{ + kprobe_opcode_t insn = *pinsn; + kprobe_opcode_t temp; + kprobe_opcode_t mask; + int freereg; + u32 free = 0xffff; + u32 regs; + + for (regs = oregs; regs; regs >>= 4, insn >>= 4) { + if ((regs & 0xf) == REG_TYPE_NONE) + continue; + + free &= ~(1 << (insn & 0xf)); + } + + /* No PC, no problem */ + if (free & (1 << 15)) + return 15; + + if (!free) + return -1; + + /* + * fls instead of ffs ensures that for "ldrd r0, r1, [pc]" we would + * pick LR instead of R1. + */ + freereg = free = fls(free) - 1; + + temp = *pinsn; + insn = *pinsn; + regs = oregs; + mask = 0xf; + + for (; regs; regs >>= 4, mask <<= 4, free <<= 4, temp >>= 4) { + if ((regs & 0xf) == REG_TYPE_NONE) + continue; + + if ((temp & 0xf) != 15) + continue; + + insn &= ~mask; + insn |= free & mask; + } + + *pinsn = insn; + return freereg; +} + +static void uprobe_set_pc(struct arch_uprobe *auprobe, + struct arch_uprobe_task *autask, + struct pt_regs *regs) +{ + u32 pcreg = auprobe->pcreg; + + autask->backup = regs->uregs[pcreg]; + regs->uregs[pcreg] = regs->ARM_pc + 8; +} + +static void uprobe_unset_pc(struct arch_uprobe *auprobe, + struct arch_uprobe_task *autask, + struct pt_regs *regs) +{ + /* PC will be taken care of by common code */ + regs->uregs[auprobe->pcreg] = autask->backup; +} + +static void uprobe_aluwrite_pc(struct arch_uprobe *auprobe, + struct arch_uprobe_task *autask, + struct pt_regs *regs) +{ + u32 pcreg = auprobe->pcreg; + + alu_write_pc(regs->uregs[pcreg], regs); + regs->uregs[pcreg] = autask->backup; +} + +static void uprobe_write_pc(struct arch_uprobe *auprobe, + struct arch_uprobe_task *autask, + struct pt_regs *regs) +{ + u32 pcreg = auprobe->pcreg; + + load_write_pc(regs->uregs[pcreg], regs); + regs->uregs[pcreg] = autask->backup; +} + +enum kprobe_insn +decode_pc_ro(kprobe_opcode_t insn, struct arch_specific_insn *asi, void *d) +{ + struct arch_uprobe *auprobe = container_of(asi, struct arch_uprobe, + asi); + struct decode_emulate *decode = d; + u32 regs = decode->header.type_regs.bits >> DECODE_TYPE_BITS; + int reg; + + reg = uprobes_substitute_pc(&auprobe->modinsn, regs); + if (reg == 15) + return INSN_GOOD; + + if (reg == -1) + return INSN_REJECTED; + + auprobe->pcreg = reg; + auprobe->prehandler = uprobe_set_pc; + auprobe->posthandler = uprobe_unset_pc; + + return INSN_GOOD; +} + +enum kprobe_insn +decode_wb_pc(kprobe_opcode_t insn, struct arch_specific_insn *asi, + void *d, bool alu) +{ + struct arch_uprobe *auprobe = container_of(asi, struct arch_uprobe, + asi); + enum kprobe_insn ret = decode_pc_ro(insn, asi, d); + + if (((insn >> 12) & 0xf) == 15) + auprobe->posthandler = alu ? uprobe_aluwrite_pc + : uprobe_write_pc; + + return ret; +} + +enum kprobe_insn +decode_rd12rn16rm0rs8_rwflags(kprobe_opcode_t insn, + struct arch_specific_insn *asi, void *d) +{ + return decode_wb_pc(insn, asi, d, true); +} + +enum kprobe_insn +decode_ldr(kprobe_opcode_t insn, struct arch_specific_insn *asi, void *d) +{ + return decode_wb_pc(insn, asi, d, false); +} + +enum kprobe_insn +uprobe_decode_ldmstm(kprobe_opcode_t insn, + struct arch_specific_insn *asi, void *d) +{ + struct arch_uprobe *auprobe = container_of(asi, struct arch_uprobe, + asi); + unsigned reglist = insn & 0xffff; + int rn = (insn >> 16) & 0xf; + int lbit = insn & (1 << 20); + unsigned used = reglist | (1 << rn); + + if (rn == 15) + return INSN_REJECTED; + + if (!(used & (1 << 15))) + return INSN_GOOD; + + if (used & (1 << 14)) + return INSN_REJECTED; + + /* Use LR instead of PC */ + insn ^= 0xc000; + + auprobe->pcreg = 14; + auprobe->modinsn = insn; + + auprobe->prehandler = uprobe_set_pc; + if (lbit) + auprobe->posthandler = uprobe_write_pc; + else + auprobe->posthandler = uprobe_unset_pc; + + return INSN_GOOD; +} + +const union decode_item uprobes_probes_actions[] = { + [PROBES_EMULATE_NONE] {.handler = kprobe_simulate_nop}, + [PROBES_SIMULATE_NOP] = {.handler = kprobe_simulate_nop}, + [PROBES_PRELOAD_IMM] = {.handler = kprobe_simulate_nop}, + [PROBES_PRELOAD_REG] = {.handler = kprobe_simulate_nop}, + [PROBES_BRANCH_IMM] = {.handler = simulate_blx1}, + [PROBES_MRS] = {.handler = simulate_mrs}, + [PROBES_BRANCH_REG] = {.handler = simulate_blx2bx}, + [PROBES_CLZ] = {.handler = kprobe_simulate_nop}, + [PROBES_SATURATING_ARITHMETIC] = {.handler = kprobe_simulate_nop}, + [PROBES_MUL1] = {.handler = kprobe_simulate_nop}, + [PROBES_MUL2] = {.handler = kprobe_simulate_nop}, + [PROBES_SWP] = {.handler = kprobe_simulate_nop}, + [PROBES_LDRSTRD] = {.decoder = decode_pc_ro}, + [PROBES_LOAD_EXTRA] = {.decoder = decode_pc_ro}, + [PROBES_LOAD] = {.decoder = decode_ldr}, + [PROBES_STORE_EXTRA] = {.decoder = decode_pc_ro}, + [PROBES_STORE] = {.decoder = decode_pc_ro}, + [PROBES_MOV_IP_SP] = {.handler = simulate_mov_ipsp}, + [PROBES_DATA_PROCESSING_REG] = { + .decoder = decode_rd12rn16rm0rs8_rwflags}, + [PROBES_DATA_PROCESSING_IMM] = { + .decoder = decode_rd12rn16rm0rs8_rwflags}, + [PROBES_MOV_HALFWORD] = {.handler = kprobe_simulate_nop}, + [PROBES_SEV] = {.handler = kprobe_simulate_nop}, + [PROBES_WFE] = {.handler = kprobe_simulate_nop}, + [PROBES_SATURATE] = {.handler = kprobe_simulate_nop}, + [PROBES_REV] = {.handler = kprobe_simulate_nop}, + [PROBES_MMI] = {.handler = kprobe_simulate_nop}, + [PROBES_PACK] = {.handler = kprobe_simulate_nop}, + [PROBES_EXTEND] = {.handler = kprobe_simulate_nop}, + [PROBES_EXTEND_ADD] = {.handler = kprobe_simulate_nop}, + [PROBES_MUL_ADD_LONG] = {.handler = kprobe_simulate_nop}, + [PROBES_MUL_ADD] = {.handler = kprobe_simulate_nop}, + [PROBES_BITFIELD] = {.handler = kprobe_simulate_nop}, + [PROBES_BRANCH] = {.handler = simulate_bbl}, + [PROBES_LDMSTM] = {.decoder = uprobe_decode_ldmstm} +}; diff --git a/arch/arm/kernel/uprobes.c b/arch/arm/kernel/uprobes.c new file mode 100644 index 0000000..2fdc668 --- /dev/null +++ b/arch/arm/kernel/uprobes.c @@ -0,0 +1,203 @@ +/* + * Copyright (C) 2012 Rabin Vincent <rabin at rab.in> + * + * 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/sched.h> +#include <linux/uprobes.h> +#include <linux/notifier.h> +#include <linux/kprobes.h> + +#include <asm/opcodes.h> +#include <asm/traps.h> + +#include "kprobes.h" +#include "uprobes.h" +#include "probes-arm.h" +#include "kprobes.h" + +bool is_swbp_insn(uprobe_opcode_t *insn) +{ + return (__mem_to_opcode_arm(*insn) & 0x0fffffff) == UPROBE_SWBP_INSN; +} + +bool arch_uprobe_ignore(struct arch_uprobe *auprobe, struct pt_regs *regs) +{ + if (!auprobe->asi.insn_check_cc(regs->ARM_cpsr)) { + regs->ARM_pc += 4; + return true; + } + + return false; +} + +bool arch_uprobe_skip_sstep(struct arch_uprobe *auprobe, struct pt_regs *regs) +{ + struct kprobe kp; + + if (!auprobe->simulate) + return false; + + kp.addr = (void *) regs->ARM_pc; + kp.opcode = __mem_to_opcode_arm(*(unsigned int *) auprobe->insn); + kp.ainsn.insn_handler = auprobe->asi.insn_handler; + + auprobe->asi.insn_singlestep(&kp, regs); + + return true; +} + +unsigned long +arch_uretprobe_hijack_return_addr(unsigned long trampoline_vaddr, + struct pt_regs *regs) +{ + regs->ARM_pc = trampoline_vaddr; + return trampoline_vaddr; +} + +int arch_uprobe_analyze_insn(struct arch_uprobe *auprobe, struct mm_struct *mm, + unsigned long addr) +{ + unsigned int insn; + unsigned int bpinsn; + enum kprobe_insn ret; + + /* Thumb not yet support */ + if (addr & 0x3) + return -EINVAL; + + insn = __mem_to_opcode_arm(*(unsigned int *)auprobe->insn); + auprobe->modinsn = insn; + + ret = arm_probes_decode_insn(insn, &auprobe->asi, true, + uprobes_probes_actions); + switch (ret) { + case INSN_REJECTED: + return -EINVAL; + + case INSN_GOOD_NO_SLOT: + auprobe->simulate = true; + break; + + case INSN_GOOD: + default: + break; + } + + bpinsn = UPROBE_SWBP_INSN; + if (insn >= 0xe0000000) + bpinsn |= 0xe0000000; /* Unconditional instruction */ + else + bpinsn |= insn & 0xf0000000; /* Copy condition from insn */ + + auprobe->bpinsn = bpinsn; + + return 0; +} + +void arch_uprobe_write_opcode(struct arch_uprobe *auprobe, void *vaddr, + uprobe_opcode_t opcode) +{ + unsigned long *addr = vaddr; + + if (opcode == UPROBE_SWBP_INSN) + opcode = __opcode_to_mem_arm(auprobe->bpinsn); + + *addr = opcode; +} + +void arch_uprobe_xol_copy(struct arch_uprobe *auprobe, void *vaddr) +{ + unsigned long *addr = vaddr; + + addr[0] = __opcode_to_mem_arm(auprobe->modinsn); + addr[1] = __opcode_to_mem_arm(0xe0000000 | UPROBE_SS_INSN); +} + +int arch_uprobe_pre_xol(struct arch_uprobe *auprobe, struct pt_regs *regs) +{ + struct uprobe_task *utask = current->utask; + + if (auprobe->prehandler) + auprobe->prehandler(auprobe, &utask->autask, regs); + + regs->ARM_pc = utask->xol_vaddr; + + return 0; +} + +int arch_uprobe_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs) +{ + struct uprobe_task *utask = current->utask; + + regs->ARM_pc = utask->vaddr + 4; + + if (auprobe->posthandler) + auprobe->posthandler(auprobe, &utask->autask, regs); + + return 0; +} + +bool arch_uprobe_xol_was_trapped(struct task_struct *t) +{ + /* TODO: implement */ + return false; +} + +void arch_uprobe_abort_xol(struct arch_uprobe *auprobe, struct pt_regs *regs) +{ + /* TODO: implement */ +} + +int arch_uprobe_exception_notify(struct notifier_block *self, + unsigned long val, void *data) +{ + return NOTIFY_DONE; +} + +static int uprobe_trap_handler(struct pt_regs *regs, unsigned int instr) +{ + unsigned long flags; + + local_irq_save(flags); + if ((instr & 0x0fffffff) == UPROBE_SWBP_INSN) + uprobe_pre_sstep_notifier(regs); + else + uprobe_post_sstep_notifier(regs); + local_irq_restore(flags); + + return 0; +} + +unsigned long uprobe_get_swbp_addr(struct pt_regs *regs) +{ + return instruction_pointer(regs); +} + +static struct undef_hook uprobes_arm_break_hook = { + .instr_mask = 0x0fffffff, + .instr_val = UPROBE_SWBP_INSN, + .cpsr_mask = MODE_MASK, + .cpsr_val = USR_MODE, + .fn = uprobe_trap_handler, +}; + +static struct undef_hook uprobes_arm_ss_hook = { + .instr_mask = 0x0fffffff, + .instr_val = UPROBE_SS_INSN, + .cpsr_mask = MODE_MASK, + .cpsr_val = USR_MODE, + .fn = uprobe_trap_handler, +}; + +int arch_uprobes_init(void) +{ + register_undef_hook(&uprobes_arm_break_hook); + register_undef_hook(&uprobes_arm_ss_hook); + + return 0; +} diff --git a/arch/arm/kernel/uprobes.h b/arch/arm/kernel/uprobes.h new file mode 100644 index 0000000..3887c19 --- /dev/null +++ b/arch/arm/kernel/uprobes.h @@ -0,0 +1,25 @@ +#ifndef __ARM_KERNEL_UPROBES_H +#define __ARM_KERNEL_UPROBES_H + +enum kprobe_insn uprobe_decode_ldmstm(kprobe_opcode_t insn, + struct arch_specific_insn *asi, + void *d); + +enum kprobe_insn decode_ldr(kprobe_opcode_t insn, + struct arch_specific_insn *asi, + void *d); + +enum kprobe_insn +decode_rd12rn16rm0rs8_rwflags(kprobe_opcode_t insn, + struct arch_specific_insn *asi, void *d); + +enum kprobe_insn +decode_wb_pc(kprobe_opcode_t insn, struct arch_specific_insn *asi, + void *d, bool alu); + +enum kprobe_insn +decode_pc_ro(kprobe_opcode_t insn, struct arch_specific_insn *asi, void *d); + +extern const union decode_item uprobes_probes_actions[]; + +#endif diff --git a/arch/powerpc/include/asm/uprobes.h b/arch/powerpc/include/asm/uprobes.h index 2301602..b532060 100644 --- a/arch/powerpc/include/asm/uprobes.h +++ b/arch/powerpc/include/asm/uprobes.h @@ -51,5 +51,4 @@ extern int arch_uprobe_post_xol(struct arch_uprobe *aup, struct pt_regs *regs); extern bool arch_uprobe_xol_was_trapped(struct task_struct *tsk); extern int arch_uprobe_exception_notify(struct notifier_block *self, unsigned long val, void *data); extern void arch_uprobe_abort_xol(struct arch_uprobe *aup, struct pt_regs *regs); -extern unsigned long arch_uretprobe_hijack_return_addr(unsigned long trampoline_vaddr, struct pt_regs *regs); #endif /* _ASM_UPROBES_H */ diff --git a/include/linux/uprobes.h b/include/linux/uprobes.h index 5eef2f0..6b292c3 100644 --- a/include/linux/uprobes.h +++ b/include/linux/uprobes.h @@ -139,6 +139,9 @@ extern int __weak arch_uprobes_init(void); extern void __weak arch_uprobe_write_opcode(struct arch_uprobe *auprobe, void *vaddr, uprobe_opcode_t opcode); +extern +unsigned long arch_uretprobe_hijack_return_addr(unsigned long trampoline_vaddr, + struct pt_regs *regs); #else /* !CONFIG_UPROBES */ struct uprobes_state { }; diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index 3b2f764..6c523ed 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -271,6 +271,7 @@ static int write_opcode(struct arch_uprobe *auprobe, struct mm_struct *mm, unsig { struct page *old_page, *new_page; struct vm_area_struct *vma; + void *vaddr_new; int ret;

retry: