arm64: spectre: provide prototypes for internal functions

The helpers in proton-pack.c are called from assembler and have
no prototype in a header, which causes a W=1 warning:

arch/arm64/kernel/proton-pack.c:568:13: error: no previous prototype for 'spectre_v4_patch_fw_mitigation_enable' [-Werror=missing-prototypes]
arch/arm64/kernel/proton-pack.c:588:13: error: no previous prototype for 'smccc_patch_fw_mitigation_conduit' [-Werror=missing-prototypes]
arch/arm64/kernel/proton-pack.c:1064:14: error: no previous prototype for 'spectre_bhb_patch_loop_mitigation_enable' [-Werror=missing-prototypes]
arch/arm64/kernel/proton-pack.c:1075:14: error: no previous prototype for 'spectre_bhb_patch_fw_mitigation_enabled' [-Werror=missing-prototypes]

Add these to asm/spectre.h, which contains related declarations
already.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20230516160642.523862-6-arnd@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

Author: arndb

arch/arm64/include/asm/spectre.h

@@ -100,5 +100,21 @@ bool is_spectre_bhb_affected(const struct arm64_cpu_capabilities *entry, int sco
 u8 spectre_bhb_loop_affected(int scope);
 void spectre_bhb_enable_mitigation(const struct arm64_cpu_capabilities *__unused);
 bool try_emulate_el1_ssbs(struct pt_regs *regs, u32 instr);
+
+void spectre_v4_patch_fw_mitigation_enable(struct alt_instr *alt, __le32 *origptr,
+					   __le32 *updptr, int nr_inst);
+void smccc_patch_fw_mitigation_conduit(struct alt_instr *alt, __le32 *origptr,
+				       __le32 *updptr, int nr_inst);
+void spectre_bhb_patch_loop_mitigation_enable(struct alt_instr *alt, __le32 *origptr,
+					      __le32 *updptr, int nr_inst);
+void spectre_bhb_patch_fw_mitigation_enabled(struct alt_instr *alt, __le32 *origptr,
+					     __le32 *updptr, int nr_inst);
+void spectre_bhb_patch_loop_iter(struct alt_instr *alt,
+				 __le32 *origptr, __le32 *updptr, int nr_inst);
+void spectre_bhb_patch_wa3(struct alt_instr *alt,
+			   __le32 *origptr, __le32 *updptr, int nr_inst);
+void spectre_bhb_patch_clearbhb(struct alt_instr *alt,
+				__le32 *origptr, __le32 *updptr, int nr_inst);
+
 #endif	/* __ASSEMBLY__ */
 #endif	/* __ASM_SPECTRE_H */