[PATCH] make prepare_frametrace() not clobber v0

[PATCH] make prepare_frametrace() not clobber v0

[Atsushi Nemoto]

Since lmo commit 323a380bf9e1a1679a774a2b053e3c1f2aa3f179 ("Simplify
dump_stack()") made prepare_frametrace() always inlined, using $2 (v0)
in __asm__ is not safe anymore.  We can use $1 (at) instead.  Also we
should use "dla" instead of "la" for 64-bit kernel.

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>

 traps.c |   10 +++++++---
 1 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c
index ab77034..e51d8fd 100644
--- a/arch/mips/kernel/traps.c
+++ b/arch/mips/kernel/traps.c
@@ -161,16 +161,20 @@ static void show_stacktrace(struct task_
 static __always_inline void prepare_frametrace(struct pt_regs *regs)
 {
 	__asm__ __volatile__(
-		"1: la $2, 1b\n\t"
+		".set push\n\t"
+		".set noat\n\t"
 #ifdef CONFIG_64BIT
-		"sd $2, %0\n\t"
+		"1: dla $1, 1b\n\t"
+		"sd $1, %0\n\t"
 		"sd $29, %1\n\t"
 		"sd $31, %2\n\t"
 #else
-		"sw $2, %0\n\t"
+		"1: la $1, 1b\n\t"
+		"sw $1, %0\n\t"
 		"sw $29, %1\n\t"
 		"sw $31, %2\n\t"
 #endif
+		".set pop\n\t"
 		: "=m" (regs->cp0_epc),
 		"=m" (regs->regs[29]), "=m" (regs->regs[31])
 		: : "memory");

Re: [PATCH] make prepare_frametrace() not clobber v0

[Franck Bui-Huu]

Atsushi Nemoto wrote:
> Since lmo commit 323a380bf9e1a1679a774a2b053e3c1f2aa3f179 ("Simplify
> dump_stack()") made prepare_frametrace() always inlined, using $2 (v0)
> in __asm__ is not safe anymore.  We can use $1 (at) instead.  Also we

Thanks, good catch !

		Franck