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Commit 049a2c2d authored by Heiko Carstens's avatar Heiko Carstens
Browse files

s390: enable CPU alternatives unconditionally 



Remove the CPU_ALTERNATIVES config option and enable the code
unconditionally. The config option was only added to avoid a conflict
with the named saved segment support. Since that code is gone there is
no reason to keep the CPU_ALTERNATIVES config option.

Just enable it unconditionally to also reduce the number of config
options and make it less likely that something breaks.

Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
parent a6de0a91

arch/s390/Kconfig

+0 −16
Original line number Diff line number Diff line
@@ -539,22 +539,6 @@ config ARCH_RANDOM 


	  If unsure, say Y.



config ALTERNATIVES

	def_bool y

	prompt "Patch optimized instructions for running CPU type"

	help

	  When enabled the kernel code is compiled with additional

	  alternative instructions blocks optimized for newer CPU types.

	  These alternative instructions blocks are patched at kernel boot

	  time when running CPU supports them. This mechanism is used to

	  optimize some critical code paths (i.e. spinlocks) for newer CPUs

	  even if kernel is build to support older machine generations.



	  This mechanism could be disabled by appending "noaltinstr"

	  option to the kernel command line.



	  If unsure, say Y.



endmenu



menu "Memory setup"

arch/s390/include/asm/alternative.h

+3 −17
Original line number Diff line number Diff line
@@ -15,14 +15,9 @@ struct alt_instr { 
	u8  replacementlen;	/* length of new instruction */

} __packed;



#ifdef CONFIG_ALTERNATIVES

extern void apply_alternative_instructions(void);

extern void apply_alternatives(struct alt_instr *start, struct alt_instr *end);

#else

static inline void apply_alternative_instructions(void) {};

static inline void apply_alternatives(struct alt_instr *start,

				      struct alt_instr *end) {};

#endif

void apply_alternative_instructions(void);

void apply_alternatives(struct alt_instr *start, struct alt_instr *end);



/*

 * |661:       |662:	  |6620      |663:

 * +-----------+---------------------+
@@ -109,7 +104,6 @@ static inline void apply_alternatives(struct alt_instr *start, 
	b_altinstr(num)":\n\t" altinstr "\n" e_altinstr(num) ":\n"	\

	INSTR_LEN_SANITY_CHECK(altinstr_len(num))



#ifdef CONFIG_ALTERNATIVES

/* alternative assembly primitive: */

#define ALTERNATIVE(oldinstr, altinstr, facility) \

	".pushsection .altinstr_replacement, \"ax\"\n"			\
@@ -130,14 +124,6 @@ static inline void apply_alternatives(struct alt_instr *start, 
	ALTINSTR_ENTRY(facility1, 1)					\

	ALTINSTR_ENTRY(facility2, 2)					\

	".popsection\n"

#else

/* Alternative instructions are disabled, let's put just oldinstr in */

#define ALTERNATIVE(oldinstr, altinstr, facility) \

	oldinstr "\n"



#define ALTERNATIVE_2(oldinstr, altinstr1, facility1, altinstr2, facility2) \

	oldinstr "\n"

#endif



/*

 * Alternative instructions for different CPU types or capabilities.

arch/s390/kernel/Makefile

+1 −2
Original line number Diff line number Diff line
@@ -59,7 +59,7 @@ obj-y += processor.o sys_s390.o ptrace.o signal.o cpcmd.o ebcdic.o nmi.o 
obj-y	+= debug.o irq.o ipl.o dis.o diag.o vdso.o als.o

obj-y	+= sysinfo.o jump_label.o lgr.o os_info.o machine_kexec.o pgm_check.o

obj-y	+= runtime_instr.o cache.o fpu.o dumpstack.o guarded_storage.o sthyi.o

obj-y	+= entry.o reipl.o relocate_kernel.o kdebugfs.o

obj-y	+= entry.o reipl.o relocate_kernel.o kdebugfs.o alternative.o



extra-y				+= head.o head64.o vmlinux.lds
@@ -77,7 +77,6 @@ obj-$(CONFIG_KPROBES) += kprobes.o 
obj-$(CONFIG_FUNCTION_TRACER)	+= mcount.o ftrace.o

obj-$(CONFIG_CRASH_DUMP)	+= crash_dump.o

obj-$(CONFIG_UPROBES)		+= uprobes.o

obj-$(CONFIG_ALTERNATIVES)	+= alternative.o



obj-$(CONFIG_PERF_EVENTS)	+= perf_event.o perf_cpum_cf.o perf_cpum_sf.o

obj-$(CONFIG_PERF_EVENTS)	+= perf_cpum_cf_events.o

arch/s390/kernel/module.c

+6 −9
Original line number Diff line number Diff line
@@ -433,18 +433,15 @@ int module_finalize(const Elf_Ehdr *hdr, 
	const Elf_Shdr *s;

	char *secstrings;



	if (IS_ENABLED(CONFIG_ALTERNATIVES)) {

	secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;

	for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) {

			if (!strcmp(".altinstructions",

				    secstrings + s->sh_name)) {

		if (!strcmp(".altinstructions", secstrings + s->sh_name)) {

			/* patch .altinstructions */

			void *aseg = (void *)s->sh_addr;



			apply_alternatives(aseg, aseg + s->sh_size);

		}

	}

	}



	jump_label_apply_nops(me);

	return 0;