diff options
| author | Uwe Kleine-König <u.kleine-koenig@pengutronix.de> | 2009-03-04 11:48:46 +0100 |
|---|---|---|
| committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2009-03-05 13:47:15 +0000 |
| commit | d4cc510c61b050ef38e842a12feef71c56d7cf81 (patch) | |
| tree | 12b3bcee76dd5252c9c6efe3ffc83d34a75b77ca | |
| parent | 843e22b056c07d39b8f97935173dab879abc613b (diff) | |
[ARM] 5418/1: restore lr before leaving mcount
gcc seems to expect that lr isn't clobbered by mcount, because for a
function starting with:
static int func(void)
{
void *ra = __builtin_return_address(0);
printk(KERN_EMERG "__builtin_return_address(0) = %pS\n", ra)
...
the following assembler is generated by gcc 4.3.2:
0: e1a0c00d mov ip, sp
4: e92dd810 push {r4, fp, ip, lr, pc}
8: e24cb004 sub fp, ip, #4 ; 0x4
c: ebfffffe bl 0 <mcount>
10: e59f0034 ldr r0, [pc, #52]
14: e1a0100e mov r1, lr
18: ebfffffe bl 0 <printk>
Without this patch obviously __builtin_return_address(0) yields
func+0x10 instead of the return address of the caller.
Note this patch fixes a similar issue for the routines used with dynamic
ftrace even though this isn't currently selectable for ARM.
Cc: Abhishek Sagar <sagar.abhishek@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
| -rw-r--r-- | arch/arm/kernel/entry-common.S | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S index 49a6ba926c2..159d0416f27 100644 --- a/arch/arm/kernel/entry-common.S +++ b/arch/arm/kernel/entry-common.S @@ -111,6 +111,7 @@ ENTRY(mcount) .globl mcount_call mcount_call: bl ftrace_stub + ldr lr, [fp, #-4] @ restore lr ldmia sp!, {r0-r3, pc} ENTRY(ftrace_caller) @@ -122,6 +123,7 @@ ENTRY(ftrace_caller) .globl ftrace_call ftrace_call: bl ftrace_stub + ldr lr, [fp, #-4] @ restore lr ldmia sp!, {r0-r3, pc} #else @@ -133,6 +135,7 @@ ENTRY(mcount) adr r0, ftrace_stub cmp r0, r2 bne trace + ldr lr, [fp, #-4] @ restore lr ldmia sp!, {r0-r3, pc} trace: @@ -141,6 +144,7 @@ trace: sub r0, r0, #MCOUNT_INSN_SIZE mov lr, pc mov pc, r2 + mov lr, r1 @ restore lr ldmia sp!, {r0-r3, pc} #endif /* CONFIG_DYNAMIC_FTRACE */ |