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Commit feb97c36 authored by Catalin Marinas's avatar Catalin Marinas Committed by Russell King
Browse files

[ARM] 5559/1: Limit the stack unwinding caused by a kthread exit 



When a kthread function returns, it branches to do_exit(). However, the
unwinding information isn't valid anymore and any stack trace caused by
do_exit() may be incorrect. This patch adds a kernel_thread_exit()
function and annotated with '.cantunwind' so that the unwinder stops
when reaching it.

Tested-by: default avatarTony Lindgren <tony@atomide.com>

Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent c894ed69

arch/arm/kernel/process.c

+18 −1
Original line number Diff line number Diff line
@@ -352,6 +352,23 @@ asm( ".section .text\n" 
"	.size	kernel_thread_helper, . - kernel_thread_helper\n"

"	.previous");



#ifdef CONFIG_ARM_UNWIND

extern void kernel_thread_exit(long code);

asm(	".section .text\n"

"	.align\n"

"	.type	kernel_thread_exit, #function\n"

"kernel_thread_exit:\n"

"	.fnstart\n"

"	.cantunwind\n"

"	bl	do_exit\n"

"	nop\n"

"	.fnend\n"

"	.size	kernel_thread_exit, . - kernel_thread_exit\n"

"	.previous");

#else

#define kernel_thread_exit	do_exit

#endif



/*

 * Create a kernel thread.

 */
@@ -363,7 +380,7 @@ pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags) 


	regs.ARM_r1 = (unsigned long)arg;

	regs.ARM_r2 = (unsigned long)fn;

	regs.ARM_r3 = (unsigned long)do_exit;

	regs.ARM_r3 = (unsigned long)kernel_thread_exit;

	regs.ARM_pc = (unsigned long)kernel_thread_helper;

	regs.ARM_cpsr = SVC_MODE | PSR_ENDSTATE;