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x86/fpu/math-emu: Fix possible uninitialized variable use 

commit 75e2f0a6b1 upstream.

When building the kernel with "make EXTRA_CFLAGS=...", this overrides
the "PARANOID" preprocessor macro defined in arch/x86/math-emu/Makefile,
and we run into a build warning:

  arch/x86/math-emu/reg_compare.c: In function ‘compare_i_st_st’:
  arch/x86/math-emu/reg_compare.c:254:6: error: ‘f’ may be used uninitialized in this function [-Werror=maybe-uninitialized]

This fixes the implementation to work correctly even without the PARANOID
flag, and also fixes the Makefile to not use the EXTRA_CFLAGS variable
but instead use the ccflags-y variable in the Makefile that is meant
for this purpose.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Bill Metzenthen <billm@melbpc.org.au>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20170719125310.2487451-3-arnd@arndb.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
steinar/wifi_calib_4_9_kernel
Arnd Bergmann 2017-07-19 14:53:00 +02:00 committed by Greg Kroah-Hartman
parent 2e44ee5fc9
commit 826a83a2f9
2 changed files with 10 additions and 10 deletions
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4
arch/x86/math-emu/Makefile
View File

@ -5,8 +5,8 @@
#DEBUG = -DDEBUGGING
DEBUG =
PARANOID = -DPARANOID
EXTRA_CFLAGS := $(PARANOID) $(DEBUG) -fno-builtin $(MATH_EMULATION)
EXTRA_AFLAGS := $(PARANOID)
ccflags-y += $(PARANOID) $(DEBUG) -fno-builtin $(MATH_EMULATION)
asflags-y += $(PARANOID)
# From 'C' language sources:
C_OBJS =fpu_entry.o errors.o \

16
arch/x86/math-emu/reg_compare.c
View File

@ -168,7 +168,7 @@ static int compare(FPU_REG const *b, int tagb)
/* This function requires that st(0) is not empty */
int FPU_compare_st_data(FPU_REG const *loaded_data, u_char loaded_tag)
{
int f = 0, c;
int f, c;
c = compare(loaded_data, loaded_tag);
@ -189,12 +189,12 @@ int FPU_compare_st_data(FPU_REG const *loaded_data, u_char loaded_tag)
case COMP_No_Comp:
f = SW_C3 | SW_C2 | SW_C0;
break;
#ifdef PARANOID
default:
#ifdef PARANOID
EXCEPTION(EX_INTERNAL | 0x121);
#endif /* PARANOID */
f = SW_C3 | SW_C2 | SW_C0;
break;
#endif /* PARANOID */
}
setcc(f);
if (c & COMP_Denormal) {
@ -205,7 +205,7 @@ int FPU_compare_st_data(FPU_REG const *loaded_data, u_char loaded_tag)
static int compare_st_st(int nr)
{
int f = 0, c;
int f, c;
FPU_REG *st_ptr;
if (!NOT_EMPTY(0) || !NOT_EMPTY(nr)) {
@ -235,12 +235,12 @@ static int compare_st_st(int nr)
case COMP_No_Comp:
f = SW_C3 | SW_C2 | SW_C0;
break;
#ifdef PARANOID
default:
#ifdef PARANOID
EXCEPTION(EX_INTERNAL | 0x122);
#endif /* PARANOID */
f = SW_C3 | SW_C2 | SW_C0;
break;
#endif /* PARANOID */
}
setcc(f);
if (c & COMP_Denormal) {
@ -283,12 +283,12 @@ static int compare_i_st_st(int nr)
case COMP_No_Comp:
f = X86_EFLAGS_ZF | X86_EFLAGS_PF | X86_EFLAGS_CF;
break;
#ifdef PARANOID
default:
#ifdef PARANOID
EXCEPTION(EX_INTERNAL | 0x122);
#endif /* PARANOID */
f = 0;
break;
#endif /* PARANOID */
}
FPU_EFLAGS = (FPU_EFLAGS & ~(X86_EFLAGS_ZF | X86_EFLAGS_PF | X86_EFLAGS_CF)) | f;
if (c & COMP_Denormal) {