A few MIPS fixes for 5.4:

- Build fixes for CONFIG_OPTIMIZE_INLINING=y builds in which the
   compiler may choose not to inline __xchg() & __cmpxchg().
 
 - A build fix for Loongson configurations with GCC 9.x.
 
 - Expose some extra HWCAP bits to indicate support for various
   instruction set extensions to userland.
 
 - Fix bad stack access in firmware handling code for old SNI
   RM200/300/400 machines.
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Merge tag 'mips_fixes_5.4_2' of git://git.kernel.org/pub/scm/linux/kernel/git/mips/linux

Pull MIPS fixes from Paul Burton:

 - Build fixes for CONFIG_OPTIMIZE_INLINING=y builds in which the
   compiler may choose not to inline __xchg() & __cmpxchg().

 - A build fix for Loongson configurations with GCC 9.x.

 - Expose some extra HWCAP bits to indicate support for various
   instruction set extensions to userland.

 - Fix bad stack access in firmware handling code for old SNI
   RM200/300/400 machines.

* tag 'mips_fixes_5.4_2' of git://git.kernel.org/pub/scm/linux/kernel/git/mips/linux:
  MIPS: Disable Loongson MMI instructions for kernel build
  MIPS: elf_hwcap: Export userspace ASEs
  MIPS: fw: sni: Fix out of bounds init of o32 stack
  MIPS: include: Mark __xchg as __always_inline
  MIPS: include: Mark __cmpxchg as __always_inline

arch/mips/fw/sni/sniprom.c

@@ -43,7 +43,7 @@
 
 /* O32 stack has to be 8-byte aligned. */
 static u64 o32_stk[4096];
-#define O32_STK	  &o32_stk[sizeof(o32_stk)]
+#define O32_STK	  (&o32_stk[ARRAY_SIZE(o32_stk)])
 
 #define __PROM_O32(fun, arg) fun arg __asm__(#fun); \
 				     __asm__(#fun " = call_o32")

arch/mips/include/asm/cmpxchg.h

@@ -77,8 +77,8 @@ extern unsigned long __xchg_called_with_bad_pointer(void)
 extern unsigned long __xchg_small(volatile void *ptr, unsigned long val,
 				  unsigned int size);
 
-static inline unsigned long __xchg(volatile void *ptr, unsigned long x,
-				   int size)
+static __always_inline
+unsigned long __xchg(volatile void *ptr, unsigned long x, int size)
 {
 	switch (size) {
 	case 1:
@@ -153,7 +153,8 @@ static inline unsigned long __xchg(volatile void *ptr, unsigned long x,
 extern unsigned long __cmpxchg_small(volatile void *ptr, unsigned long old,
 				     unsigned long new, unsigned int size);
 
-static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old,
+static __always_inline
+unsigned long __cmpxchg(volatile void *ptr, unsigned long old,
 			unsigned long new, unsigned int size)
 {
 	switch (size) {

arch/mips/include/uapi/asm/hwcap.h

@@ -6,5 +6,16 @@
 #define HWCAP_MIPS_R6		(1 << 0)
 #define HWCAP_MIPS_MSA		(1 << 1)
 #define HWCAP_MIPS_CRC32	(1 << 2)
+#define HWCAP_MIPS_MIPS16	(1 << 3)
+#define HWCAP_MIPS_MDMX     (1 << 4)
+#define HWCAP_MIPS_MIPS3D   (1 << 5)
+#define HWCAP_MIPS_SMARTMIPS (1 << 6)
+#define HWCAP_MIPS_DSP      (1 << 7)
+#define HWCAP_MIPS_DSP2     (1 << 8)
+#define HWCAP_MIPS_DSP3     (1 << 9)
+#define HWCAP_MIPS_MIPS16E2 (1 << 10)
+#define HWCAP_LOONGSON_MMI  (1 << 11)
+#define HWCAP_LOONGSON_EXT  (1 << 12)
+#define HWCAP_LOONGSON_EXT2 (1 << 13)
 
 #endif /* _UAPI_ASM_HWCAP_H */

arch/mips/kernel/cpu-probe.c

@@ -2180,6 +2180,39 @@ void cpu_probe(void)
 		elf_hwcap |= HWCAP_MIPS_MSA;
 	}
 
+	if (cpu_has_mips16)
+		elf_hwcap |= HWCAP_MIPS_MIPS16;
+
+	if (cpu_has_mdmx)
+		elf_hwcap |= HWCAP_MIPS_MDMX;
+
+	if (cpu_has_mips3d)
+		elf_hwcap |= HWCAP_MIPS_MIPS3D;
+
+	if (cpu_has_smartmips)
+		elf_hwcap |= HWCAP_MIPS_SMARTMIPS;
+
+	if (cpu_has_dsp)
+		elf_hwcap |= HWCAP_MIPS_DSP;
+
+	if (cpu_has_dsp2)
+		elf_hwcap |= HWCAP_MIPS_DSP2;
+
+	if (cpu_has_dsp3)
+		elf_hwcap |= HWCAP_MIPS_DSP3;
+
+	if (cpu_has_mips16e2)
+		elf_hwcap |= HWCAP_MIPS_MIPS16E2;
+
+	if (cpu_has_loongson_mmi)
+		elf_hwcap |= HWCAP_LOONGSON_MMI;
+
+	if (cpu_has_loongson_ext)
+		elf_hwcap |= HWCAP_LOONGSON_EXT;
+
+	if (cpu_has_loongson_ext2)
+		elf_hwcap |= HWCAP_LOONGSON_EXT2;
+
 	if (cpu_has_vz)
 		cpu_probe_vz(c);
 

arch/mips/loongson64/Platform

@@ -66,6 +66,10 @@ else
       $(call cc-option,-march=mips64r2,-mips64r2 -U_MIPS_ISA -D_MIPS_ISA=_MIPS_ISA_MIPS64)
 endif
 
+# Some -march= flags enable MMI instructions, and GCC complains about that
+# support being enabled alongside -msoft-float. Thus explicitly disable MMI.
+cflags-y += $(call cc-option,-mno-loongson-mmi)
+
 #
 # Loongson Machines' Support
 #

arch/mips/vdso/Makefile

@@ -15,6 +15,7 @@ ccflags-vdso := \
 	$(filter -mmicromips,$(KBUILD_CFLAGS)) \
 	$(filter -march=%,$(KBUILD_CFLAGS)) \
 	$(filter -m%-float,$(KBUILD_CFLAGS)) \
+	$(filter -mno-loongson-%,$(KBUILD_CFLAGS)) \
 	-D__VDSO__
 
 ifdef CONFIG_CC_IS_CLANG