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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: Heiko Carstens <heiko.carstens@de.ibm.com>
This commit is contained in:
Heiko Carstens 2017-11-14 15:20:24 +01:00
parent a6de0a91d9
commit 049a2c2d48
4 changed files with 10 additions and 44 deletions
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16
arch/s390/Kconfig
View File

@ -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"

20
arch/s390/include/asm/alternative.h
View File

@ -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.

3
arch/s390/kernel/Makefile
View File

@ -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

15
arch/s390/kernel/module.c
View File

@ -433,16 +433,13 @@ 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)) {
/* patch .altinstructions */
void *aseg = (void *)s->sh_addr;
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)) {
/* patch .altinstructions */
void *aseg = (void *)s->sh_addr;
apply_alternatives(aseg, aseg + s->sh_size);
}
apply_alternatives(aseg, aseg + s->sh_size);
}
}