Copying a function with memcpy() and then trying to execute the result isn't trivially portable to Thumb.

This patch modifies the kexec soft restart code to copy its assembler trampoline relocate_new_kernel() using fncpy() instead, so that relocate_new_kernel can be in the same ISA as the rest of the kernel without problems.

Signed-off-by: Dave Martin Dave.Martin@arm.com --- Tested on Versatile Express TC2, to boot an ARM kernel from Thumb and vice-versa.

I believe this brings v7M compatibility closer, but we still need to avoid the final "bx lr" attempting to switch to ARM in that case -- I think that will undef or fault or something. I don't think we need to worry about that until someone actually wants it to work. This patch should not increase the amount of brokenness for v7M.

arch/arm/kernel/machine_kexec.c | 17 ++++++++++------- arch/arm/kernel/relocate_kernel.S | 8 ++++++-- 2 files changed, 16 insertions(+), 9 deletions(-)

diff --git a/arch/arm/kernel/machine_kexec.c b/arch/arm/kernel/machine_kexec.c index 57221e3..f0d180d 100644 --- a/arch/arm/kernel/machine_kexec.c +++ b/arch/arm/kernel/machine_kexec.c @@ -14,11 +14,12 @@ #include <asm/pgalloc.h> #include <asm/mmu_context.h> #include <asm/cacheflush.h> +#include <asm/fncpy.h> #include <asm/mach-types.h> #include <asm/smp_plat.h> #include <asm/system_misc.h>

-extern const unsigned char relocate_new_kernel[]; +extern void relocate_new_kernel(void); extern const unsigned int relocate_new_kernel_size;

extern unsigned long kexec_start_address; @@ -142,6 +143,8 @@ void machine_kexec(struct kimage *image) { unsigned long page_list; unsigned long reboot_code_buffer_phys; + unsigned long reboot_entry = (unsigned long)relocate_new_kernel; + unsigned long reboot_entry_phys; void *reboot_code_buffer;

/* @@ -168,16 +171,16 @@ void machine_kexec(struct kimage *image)

/* copy our kernel relocation code to the control code page */ - memcpy(reboot_code_buffer, - relocate_new_kernel, relocate_new_kernel_size); + reboot_entry = fncpy(reboot_code_buffer, + reboot_entry, + relocate_new_kernel_size); + reboot_entry_phys = (unsigned long)reboot_entry + + (reboot_code_buffer_phys - (unsigned long)reboot_code_buffer);

- - flush_icache_range((unsigned long) reboot_code_buffer, - (unsigned long) reboot_code_buffer + KEXEC_CONTROL_PAGE_SIZE); printk(KERN_INFO "Bye!\n");

if (kexec_reinit) kexec_reinit();

- soft_restart(reboot_code_buffer_phys); + soft_restart(reboot_entry_phys); } diff --git a/arch/arm/kernel/relocate_kernel.S b/arch/arm/kernel/relocate_kernel.S index d0cdedf..f2c1691 100644 --- a/arch/arm/kernel/relocate_kernel.S +++ b/arch/arm/kernel/relocate_kernel.S @@ -2,10 +2,12 @@ * relocate_kernel.S - put the kernel image in place to boot */

+#include <linux/linkage.h> #include <asm/kexec.h>

- .globl relocate_new_kernel -relocate_new_kernel: + .align 3 /* not needed for this code, but keeps fncpy() happy */ + +ENTRY(relocate_new_kernel)

ldr r0,kexec_indirection_page ldr r1,kexec_start_address @@ -60,6 +62,8 @@ relocate_new_kernel: ARM( mov pc, lr ) THUMB( bx lr )

+ENDPROC(relocate_new_kernel) + .align

.globl kexec_start_address