powerpc/math-emu: Inhibit W=1 warnings

When building with W=1 you get:

	arch/powerpc/math-emu/fre.c:6:5: error: no previous prototype for 'fre' [-Werror=missing-prototypes]
	arch/powerpc/math-emu/fsqrt.c:11:1: error: no previous prototype for 'fsqrt' [-Werror=missing-prototypes]
	arch/powerpc/math-emu/fsqrts.c:12:1: error: no previous prototype for 'fsqrts' [-Werror=missing-prototypes]
	arch/powerpc/math-emu/frsqrtes.c:6:5: error: no previous prototype for 'frsqrtes' [-Werror=missing-prototypes]
	arch/powerpc/math-emu/mtfsf.c:10:1: error: no previous prototype for 'mtfsf' [-Werror=missing-prototypes]
	arch/powerpc/math-emu/mtfsfi.c:10:1: error: no previous prototype for 'mtfsfi' [-Werror=missing-prototypes]
	arch/powerpc/math-emu/fabs.c:7:1: error: no previous prototype for 'fabs' [-Werror=missing-prototypes]
	arch/powerpc/math-emu/fadd.c:11:1: error: no previous prototype for 'fadd' [-Werror=missing-prototypes]
	arch/powerpc/math-emu/fadds.c:12:1: error: no previous prototype for 'fadds' [-Werror=missing-prototypes]
	arch/powerpc/math-emu/fcmpo.c:11:1: error: no previous prototype for 'fcmpo' [-Werror=missing-prototypes]
	arch/powerpc/math-emu/fcmpu.c:11:1: error: no previous prototype for 'fcmpu' [-Werror=missing-prototypes]
	arch/powerpc/math-emu/fcmpu.c:14:19: error: variable 'B_c' set but not used [-Werror=unused-but-set-variable]
	arch/powerpc/math-emu/fcmpu.c:13:19: error: variable 'A_c' set but not used [-Werror=unused-but-set-variable]
	arch/powerpc/math-emu/fctiw.c:11:1: error: no previous prototype for 'fctiw' [-Werror=missing-prototypes]
	arch/powerpc/math-emu/fctiwz.c:11:1: error: no previous prototype for 'fctiwz' [-Werror=missing-prototypes]
	arch/powerpc/math-emu/fdiv.c:11:1: error: no previous prototype for 'fdiv' [-Werror=missing-prototypes]
	arch/powerpc/math-emu/fdivs.c:12:1: error: no previous prototype for 'fdivs' [-Werror=missing-prototypes]
	arch/powerpc/math-emu/fmadd.c:11:1: error: no previous prototype for 'fmadd' [-Werror=missing-prototypes]
	arch/powerpc/math-emu/fmadds.c:12:1: error: no previous prototype for 'fmadds' [-Werror=missing-prototypes]
	arch/powerpc/math-emu/fmsub.c:11:1: error: no previous prototype for 'fmsub' [-Werror=missing-prototypes]
	arch/powerpc/math-emu/fmsubs.c:12:1: error: no previous prototype for 'fmsubs' [-Werror=missing-prototypes]
	arch/powerpc/math-emu/fmul.c:11:1: error: no previous prototype for 'fmul' [-Werror=missing-prototypes]
	arch/powerpc/math-emu/fmuls.c:12:1: error: no previous prototype for 'fmuls' [-Werror=missing-prototypes]
	arch/powerpc/math-emu/fnabs.c:7:1: error: no previous prototype for 'fnabs' [-Werror=missing-prototypes]
	arch/powerpc/math-emu/fneg.c:7:1: error: no previous prototype for 'fneg' [-Werror=missing-prototypes]
	arch/powerpc/math-emu/fnmadd.c:11:1: error: no previous prototype for 'fnmadd' [-Werror=missing-prototypes]
	arch/powerpc/math-emu/fnmadds.c:12:1: error: no previous prototype for 'fnmadds' [-Werror=missing-prototypes]
	arch/powerpc/math-emu/fnmsub.c:11:1: error: no previous prototype for 'fnmsub' [-Werror=missing-prototypes]
	arch/powerpc/math-emu/fnmsubs.c:12:1: error: no previous prototype for 'fnmsubs' [-Werror=missing-prototypes]
	arch/powerpc/math-emu/fres.c:7:1: error: no previous prototype for 'fres' [-Werror=missing-prototypes]
	arch/powerpc/math-emu/frsp.c:12:1: error: no previous prototype for 'frsp' [-Werror=missing-prototypes]
	arch/powerpc/math-emu/fsel.c:11:1: error: no previous prototype for 'fsel' [-Werror=missing-prototypes]
	arch/powerpc/math-emu/lfs.c:12:1: error: no previous prototype for 'lfs' [-Werror=missing-prototypes]
	arch/powerpc/math-emu/frsqrte.c:7:1: error: no previous prototype for 'frsqrte' [-Werror=missing-prototypes]
	arch/powerpc/math-emu/fsub.c:11:1: error: no previous prototype for 'fsub' [-Werror=missing-prototypes]
	arch/powerpc/math-emu/fsubs.c:12:1: error: no previous prototype for 'fsubs' [-Werror=missing-prototypes]
	arch/powerpc/math-emu/mcrfs.c:10:1: error: no previous prototype for 'mcrfs' [-Werror=missing-prototypes]
	arch/powerpc/math-emu/mffs.c:10:1: error: no previous prototype for 'mffs' [-Werror=missing-prototypes]
	arch/powerpc/math-emu/mtfsb0.c:10:1: error: no previous prototype for 'mtfsb0' [-Werror=missing-prototypes]
	arch/powerpc/math-emu/mtfsb1.c:10:1: error: no previous prototype for 'mtfsb1' [-Werror=missing-prototypes]
	arch/powerpc/math-emu/stfiwx.c:7:1: error: no previous prototype for 'stfiwx' [-Werror=missing-prototypes]
	arch/powerpc/math-emu/stfs.c:12:1: error: no previous prototype for 'stfs' [-Werror=missing-prototypes]
	arch/powerpc/math-emu/fmr.c:7:1: error: no previous prototype for 'fmr' [-Werror=missing-prototypes]
	arch/powerpc/math-emu/lfd.c:10:1: error: no previous prototype for 'lfd' [-Werror=missing-prototypes]
	arch/powerpc/math-emu/stfd.c:7:1: error: no previous prototype for 'stfd' [-Werror=missing-prototypes]
	arch/powerpc/math-emu/math_efp.c:177:5: error: no previous prototype for 'do_spe_mathemu' [-Werror=missing-prototypes]
	arch/powerpc/math-emu/math_efp.c:726:5: error: no previous prototype for 'speround_handler' [-Werror=missing-prototypes]
	arch/powerpc/math-emu/math_efp.c:893:12: error: no previous prototype for 'spe_mathemu_init' [-Werror=missing-prototypes]

Fix the warnings in math_efp.c by adding prototypes of do_spe_mathemu()
and speround_handler() to asm/processor.h and declare spe_mathemu_init()
static.

The other warnings are benign and not worth the churn of fixing them,
expecially the 'unused-but-set-variable' which would impact the core
part of 'math-emu'.

So silence them by adding -Wno-missing-prototypes -Wno-unused-but-set-variable.

But then you get:

	arch/powerpc/math-emu/fre.c:6:5: error: no previous declaration for 'fre' [-Werror=missing-declarations]
	arch/powerpc/math-emu/fsqrt.c:11:1: error: no previous declaration for 'fsqrt' [-Werror=missing-declarations]
	arch/powerpc/math-emu/fsqrts.c:12:1: error: no previous declaration for 'fsqrts' [-Werror=missing-declarations]
	arch/powerpc/math-emu/frsqrtes.c:6:5: error: no previous declaration for 'frsqrtes' [-Werror=missing-declarations]
	arch/powerpc/math-emu/mtfsf.c:10:1: error: no previous declaration for 'mtfsf' [-Werror=missing-declarations]
	arch/powerpc/math-emu/mtfsfi.c:10:1: error: no previous declaration for 'mtfsfi' [-Werror=missing-declarations]
	arch/powerpc/math-emu/fabs.c:7:1: error: no previous declaration for 'fabs' [-Werror=missing-declarations]
	arch/powerpc/math-emu/fadd.c:11:1: error: no previous declaration for 'fadd' [-Werror=missing-declarations]
	arch/powerpc/math-emu/fadds.c:12:1: error: no previous declaration for 'fadds' [-Werror=missing-declarations]
	arch/powerpc/math-emu/fcmpo.c:11:1: error: no previous declaration for 'fcmpo' [-Werror=missing-declarations]
	arch/powerpc/math-emu/fcmpu.c:11:1: error: no previous declaration for 'fcmpu' [-Werror=missing-declarations]
	arch/powerpc/math-emu/fctiw.c:11:1: error: no previous declaration for 'fctiw' [-Werror=missing-declarations]
	arch/powerpc/math-emu/fctiwz.c:11:1: error: no previous declaration for 'fctiwz' [-Werror=missing-declarations]
	arch/powerpc/math-emu/fdiv.c:11:1: error: no previous declaration for 'fdiv' [-Werror=missing-declarations]
	arch/powerpc/math-emu/fdivs.c:12:1: error: no previous declaration for 'fdivs' [-Werror=missing-declarations]
	arch/powerpc/math-emu/fmadd.c:11:1: error: no previous declaration for 'fmadd' [-Werror=missing-declarations]
	arch/powerpc/math-emu/fmadds.c:12:1: error: no previous declaration for 'fmadds' [-Werror=missing-declarations]
	arch/powerpc/math-emu/fmsub.c:11:1: error: no previous declaration for 'fmsub' [-Werror=missing-declarations]
	arch/powerpc/math-emu/fmsubs.c:12:1: error: no previous declaration for 'fmsubs' [-Werror=missing-declarations]
	arch/powerpc/math-emu/fmul.c:11:1: error: no previous declaration for 'fmul' [-Werror=missing-declarations]
	arch/powerpc/math-emu/fmuls.c:12:1: error: no previous declaration for 'fmuls' [-Werror=missing-declarations]
	arch/powerpc/math-emu/fnabs.c:7:1: error: no previous declaration for 'fnabs' [-Werror=missing-declarations]
	arch/powerpc/math-emu/fneg.c:7:1: error: no previous declaration for 'fneg' [-Werror=missing-declarations]
	arch/powerpc/math-emu/fnmadd.c:11:1: error: no previous declaration for 'fnmadd' [-Werror=missing-declarations]
	arch/powerpc/math-emu/fnmadds.c:12:1: error: no previous declaration for 'fnmadds' [-Werror=missing-declarations]
	arch/powerpc/math-emu/fnmsub.c:11:1: error: no previous declaration for 'fnmsub' [-Werror=missing-declarations]
	arch/powerpc/math-emu/fnmsubs.c:12:1: error: no previous declaration for 'fnmsubs' [-Werror=missing-declarations]
	arch/powerpc/math-emu/fres.c:7:1: error: no previous declaration for 'fres' [-Werror=missing-declarations]
	arch/powerpc/math-emu/frsp.c:12:1: error: no previous declaration for 'frsp' [-Werror=missing-declarations]
	arch/powerpc/math-emu/fsel.c:11:1: error: no previous declaration for 'fsel' [-Werror=missing-declarations]
	arch/powerpc/math-emu/lfs.c:12:1: error: no previous declaration for 'lfs' [-Werror=missing-declarations]
	arch/powerpc/math-emu/frsqrte.c:7:1: error: no previous declaration for 'frsqrte' [-Werror=missing-declarations]
	arch/powerpc/math-emu/fsub.c:11:1: error: no previous declaration for 'fsub' [-Werror=missing-declarations]
	arch/powerpc/math-emu/fsubs.c:12:1: error: no previous declaration for 'fsubs' [-Werror=missing-declarations]
	arch/powerpc/math-emu/mcrfs.c:10:1: error: no previous declaration for 'mcrfs' [-Werror=missing-declarations]
	arch/powerpc/math-emu/mffs.c:10:1: error: no previous declaration for 'mffs' [-Werror=missing-declarations]
	arch/powerpc/math-emu/mtfsb0.c:10:1: error: no previous declaration for 'mtfsb0' [-Werror=missing-declarations]
	arch/powerpc/math-emu/mtfsb1.c:10:1: error: no previous declaration for 'mtfsb1' [-Werror=missing-declarations]
	arch/powerpc/math-emu/stfiwx.c:7:1: error: no previous declaration for 'stfiwx' [-Werror=missing-declarations]
	arch/powerpc/math-emu/stfs.c:12:1: error: no previous declaration for 'stfs' [-Werror=missing-declarations]
	arch/powerpc/math-emu/fmr.c:7:1: error: no previous declaration for 'fmr' [-Werror=missing-declarations]
	arch/powerpc/math-emu/lfd.c:10:1: error: no previous declaration for 'lfd' [-Werror=missing-declarations]
	arch/powerpc/math-emu/stfd.c:7:1: error: no previous declaration for 'stfd' [-Werror=missing-declarations]

So also add -Wno-missing-declarations.

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/688084b40b5ac88f2905cb207d5dad947d8d34dc.1662531153.git.christophe.leroy@csgroup.eu

arch/powerpc/include/asm/processor.h

@@ -426,6 +426,8 @@ extern int fix_alignment(struct pt_regs *);
 #endif
 
 int do_mathemu(struct pt_regs *regs);
+int do_spe_mathemu(struct pt_regs *regs);
+int speround_handler(struct pt_regs *regs);
 
 /* VMX copying */
 int enter_vmx_usercopy(void);

arch/powerpc/kernel/traps.c

@@ -2103,7 +2103,6 @@ DEFINE_INTERRUPT_HANDLER(CacheLockingException)
 #ifdef CONFIG_SPE
 DEFINE_INTERRUPT_HANDLER(SPEFloatingPointException)
 {
-	extern int do_spe_mathemu(struct pt_regs *regs);
 	unsigned long spefscr;
 	int fpexc_mode;
 	int code = FPE_FLTUNK;
@@ -2153,7 +2152,6 @@ DEFINE_INTERRUPT_HANDLER(SPEFloatingPointException)
 
 DEFINE_INTERRUPT_HANDLER(SPEFloatingPointRoundException)
 {
-	extern int speround_handler(struct pt_regs *regs);
 	int err;
 
 	interrupt_cond_local_irq_enable(regs);

arch/powerpc/math-emu/Makefile

@@ -16,3 +16,10 @@ obj-$(CONFIG_SPE)		+= math_efp.o
 
 CFLAGS_fabs.o = -fno-builtin-fabs
 CFLAGS_math.o = -fno-builtin-fabs
+
+ccflags-remove-y = -Wmissing-prototypes -Wmissing-declarations -Wunused-but-set-variable
+
+ifdef KBUILD_EXTRA_WARN
+CFLAGS_math.o += -Wmissing-prototypes -Wmissing-declarations -Wunused-but-set-variable
+CFLAGS_math_efp.o += -Wmissing-prototypes -Wmissing-declarations -Wunused-but-set-variable
+endif

arch/powerpc/math-emu/math_efp.c

@@ -890,7 +890,7 @@ int speround_handler(struct pt_regs *regs)
 	return 0;
 }
 
-int __init spe_mathemu_init(void)
+static int __init spe_mathemu_init(void)
 {
 	u32 pvr, maj, min;