Commit 8a574cfa authored Sep 16, 2014 by Markos Chandras Committed by Ralf Baechle Sep 26, 2014

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 58b69401
(MIPS: Function tracer: Fix broken function tracing).

Commit ad8c3969 ("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>

parent c8c0da6b

arch/mips/kernel/mcount.S

+12 −0

Original line number	Diff line number	Diff line
		@@ -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)

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