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authorUwe Kleine-König <u.kleine-koenig@pengutronix.de>2009-03-04 11:48:46 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2009-03-05 13:47:15 +0000
commitd4cc510c61b050ef38e842a12feef71c56d7cf81 (patch)
tree12b3bcee76dd5252c9c6efe3ffc83d34a75b77ca
parent843e22b056c07d39b8f97935173dab879abc613b (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.S4
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 */