[PATCH] powerpc/process: Fix uninitialised variable error

[PATCH] powerpc/process: Fix uninitialised variable error

[Michael Ellerman]

Clang, and GCC with -Wmaybe-uninitialized, can't see that val is
unused in get_fpexec_mode():

  arch/powerpc/kernel/process.c:1940:7: error: variable 'val' is used
  uninitialized whenever 'if' condition is true
		  if (cpu_has_feature(CPU_FTR_SPE)) {
		      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~

We know that CPU_FTR_SPE will only be true iff CONFIG_SPE is also
true, but the compiler doesn't.

Avoid it by initialising val to zero.

Reported-by: kernel test robot <lkp@intel.com>
Fixes: 532ed1900d37 ("powerpc/process: Remove useless #ifdef CONFIG_SPE")
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
---
 arch/powerpc/kernel/process.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 14d5189b17d8..d421a2c7f822 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1934,7 +1934,7 @@ int set_fpexc_mode(struct task_struct *tsk, unsigned int val)
 
 int get_fpexc_mode(struct task_struct *tsk, unsigned long adr)
 {
-	unsigned int val;
+	unsigned int val = 0;
 
 	if (tsk->thread.fpexc_mode & PR_FP_EXC_SW_ENABLE) {
 		if (cpu_has_feature(CPU_FTR_SPE)) {
-- 
2.25.1

Re: [PATCH] powerpc/process: Fix uninitialised variable error

[Nick Desaulniers]

https://lore.kernel.org/linuxppc-dev/20200917024509.3253837-1-mpe@ellerman.id.au/

Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>

Re: [PATCH] powerpc/process: Fix uninitialised variable error

[Michael Ellerman]

On Thu, 17 Sep 2020 12:45:09 +1000, Michael Ellerman wrote:
> Clang, and GCC with -Wmaybe-uninitialized, can't see that val is
> unused in get_fpexec_mode():
> 
>   arch/powerpc/kernel/process.c:1940:7: error: variable 'val' is used
>   uninitialized whenever 'if' condition is true
> 		  if (cpu_has_feature(CPU_FTR_SPE)) {
> 		      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 
> [...]

Applied to powerpc/next.

[1/1] powerpc/process: Fix uninitialised variable error
      https://git.kernel.org/powerpc/c/d208e13c6a2277d9fb71fad6a1394c70bdd7b634

cheers