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MIPS: mcount: Adjust stack pointer for static trace in MIPS32 

Every mcount() call in the MIPS 32-bit kernel is done as follows:

[...]
move at, ra
jal _mcount
addiu sp, sp, -8
[...]

but upon returning from the mcount() function, the stack pointer
is not adjusted properly. This is explained in details in 58b69401c7
(MIPS: Function tracer: Fix broken function tracing).

Commit ad8c396936 ("MIPS: Unbreak function tracer for 64-bit kernel.)
fixed the stack manipulation for 64-bit but it didn't fix it completely
for MIPS32.

Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: <stable@vger.kernel.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/7792/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
This commit is contained in:
Markos Chandras 2014-09-16 15:55:12 +01:00 committed by Ralf Baechle
parent c8c0da6bdf
commit 8a574cfa26
1 changed files with 12 additions and 0 deletions
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12
arch/mips/kernel/mcount.S
View File

@ -129,7 +129,11 @@ NESTED(_mcount, PT_SIZE, ra)
nop
#endif
b ftrace_stub
#ifdef CONFIG_32BIT
addiu sp, sp, 8
#else
nop
#endif
static_trace:
MCOUNT_SAVE_REGS
@ -139,6 +143,9 @@ static_trace:
move a1, AT /* arg2: parent's return address */
MCOUNT_RESTORE_REGS
#ifdef CONFIG_32BIT
addiu sp, sp, 8
#endif
.globl ftrace_stub
ftrace_stub:
RETURN_BACK
@ -183,6 +190,11 @@ NESTED(ftrace_graph_caller, PT_SIZE, ra)
jal prepare_ftrace_return
nop
MCOUNT_RESTORE_REGS
#ifndef CONFIG_DYNAMIC_FTRACE
#ifdef CONFIG_32BIT
addiu sp, sp, 8
#endif
#endif
RETURN_BACK
END(ftrace_graph_caller)