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Message-Id: <20180427135711.142503645@linuxfoundation.org>
Date: Fri, 27 Apr 2018 15:58:19 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org,
Martin Schwidefsky <schwidefsky@...ibm.com>,
Heiko Carstens <heiko.carstens@...ibm.com>
Subject: [PATCH 4.9 29/74] s390: enable CPU alternatives unconditionally
4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Martin Schwidefsky <schwidefsky@...ibm.com>
From: Heiko Carstens <heiko.carstens@...ibm.com>
[ Upstream commit 049a2c2d486e8cc82c5cd79fa479c5b105b109e9 ]
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@...ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@...ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
arch/s390/Kconfig | 16 ----------------
arch/s390/include/asm/alternative.h | 20 +++-----------------
arch/s390/kernel/Makefile | 3 +--
arch/s390/kernel/module.c | 15 ++++++---------
4 files changed, 10 insertions(+), 44 deletions(-)
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -704,22 +704,6 @@ config SECCOMP
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 "Power Management"
--- a/arch/s390/include/asm/alternative.h
+++ b/arch/s390/include/asm/alternative.h
@@ -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(st
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(st
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.
--- a/arch/s390/kernel/Makefile
+++ b/arch/s390/kernel/Makefile
@@ -57,7 +57,7 @@ obj-y += processor.o sys_s390.o ptrace.o
obj-y += debug.o irq.o ipl.o dis.o diag.o sclp.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
-obj-y += entry.o reipl.o relocate_kernel.o
+obj-y += entry.o reipl.o relocate_kernel.o alternative.o
extra-y += head.o head64.o vmlinux.lds
@@ -75,7 +75,6 @@ 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
--- a/arch/s390/kernel/module.c
+++ b/arch/s390/kernel/module.c
@@ -432,16 +432,13 @@ 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);
}
}
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