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

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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: Tony Lindgren <tony@atomide.com>

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Catalin Marinas 2009-06-19 16:43:08 +01:00 committed by Russell King
parent c894ed6956
commit feb97c3644
1 changed files with 18 additions and 1 deletions
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19
arch/arm/kernel/process.c
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@ -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;