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author | Gerd Hoffmann <kraxel@suse.de> | 2006-06-26 13:56:16 +0200 |
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committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-06-26 10:48:14 -0700 |
commit | d167a51877e94dda73dd656c51f363502309f713 (patch) | |
tree | eb02c2974b61777f575dfdc07d4c2adf83bde434 /include/asm-x86_64/alternative.h | |
parent | 240cd6a80642da528bfa382ec2ae4e3cb8991ea7 (diff) | |
download | kernel_samsung_smdk4412-d167a51877e94dda73dd656c51f363502309f713.zip kernel_samsung_smdk4412-d167a51877e94dda73dd656c51f363502309f713.tar.gz kernel_samsung_smdk4412-d167a51877e94dda73dd656c51f363502309f713.tar.bz2 |
[PATCH] x86_64: x86_64 version of the smp alternative patch.
Changes are largely identical to the i386 version:
* alternative #define are moved to the new alternative.h file.
* one new elf section with pointers to the lock prefixes which can be
nop'ed out for non-smp.
* two new elf sections simliar to the "classic" alternatives to
replace SMP code with simpler UP code.
* fixup headers to use alternative.h instead of defining their own
LOCK / LOCK_PREFIX macros.
The patch reuses the i386 version of the alternatives code to avoid code
duplication. The code in alternatives.c was shuffled around a bit to
reduce the number of #ifdefs needed. It also got some tweaks needed for
x86_64 (vsyscall page handling) and new features (noreplacement option
which was x86_64 only up to now). Debug printk's are changed from
compile-time to runtime.
Loosely based on a early version from Bastian Blank <waldi@debian.org>
Signed-off-by: Gerd Hoffmann <kraxel@suse.de>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'include/asm-x86_64/alternative.h')
-rw-r--r-- | include/asm-x86_64/alternative.h | 146 |
1 files changed, 146 insertions, 0 deletions
diff --git a/include/asm-x86_64/alternative.h b/include/asm-x86_64/alternative.h new file mode 100644 index 0000000..387c8f6 --- /dev/null +++ b/include/asm-x86_64/alternative.h @@ -0,0 +1,146 @@ +#ifndef _X86_64_ALTERNATIVE_H +#define _X86_64_ALTERNATIVE_H + +#ifdef __KERNEL__ + +#include <linux/types.h> + +struct alt_instr { + u8 *instr; /* original instruction */ + u8 *replacement; + u8 cpuid; /* cpuid bit set for replacement */ + u8 instrlen; /* length of original instruction */ + u8 replacementlen; /* length of new instruction, <= instrlen */ + u8 pad[5]; +}; + +extern void apply_alternatives(struct alt_instr *start, struct alt_instr *end); + +struct module; +extern void alternatives_smp_module_add(struct module *mod, char *name, + void *locks, void *locks_end, + void *text, void *text_end); +extern void alternatives_smp_module_del(struct module *mod); +extern void alternatives_smp_switch(int smp); + +#endif + +/* + * Alternative instructions for different CPU types or capabilities. + * + * This allows to use optimized instructions even on generic binary + * kernels. + * + * length of oldinstr must be longer or equal the length of newinstr + * It can be padded with nops as needed. + * + * For non barrier like inlines please define new variants + * without volatile and memory clobber. + */ +#define alternative(oldinstr, newinstr, feature) \ + asm volatile ("661:\n\t" oldinstr "\n662:\n" \ + ".section .altinstructions,\"a\"\n" \ + " .align 8\n" \ + " .quad 661b\n" /* label */ \ + " .quad 663f\n" /* new instruction */ \ + " .byte %c0\n" /* feature bit */ \ + " .byte 662b-661b\n" /* sourcelen */ \ + " .byte 664f-663f\n" /* replacementlen */ \ + ".previous\n" \ + ".section .altinstr_replacement,\"ax\"\n" \ + "663:\n\t" newinstr "\n664:\n" /* replacement */ \ + ".previous" :: "i" (feature) : "memory") + +/* + * Alternative inline assembly with input. + * + * Pecularities: + * No memory clobber here. + * Argument numbers start with 1. + * Best is to use constraints that are fixed size (like (%1) ... "r") + * If you use variable sized constraints like "m" or "g" in the + * replacement make sure to pad to the worst case length. + */ +#define alternative_input(oldinstr, newinstr, feature, input...) \ + asm volatile ("661:\n\t" oldinstr "\n662:\n" \ + ".section .altinstructions,\"a\"\n" \ + " .align 8\n" \ + " .quad 661b\n" /* label */ \ + " .quad 663f\n" /* new instruction */ \ + " .byte %c0\n" /* feature bit */ \ + " .byte 662b-661b\n" /* sourcelen */ \ + " .byte 664f-663f\n" /* replacementlen */ \ + ".previous\n" \ + ".section .altinstr_replacement,\"ax\"\n" \ + "663:\n\t" newinstr "\n664:\n" /* replacement */ \ + ".previous" :: "i" (feature), ##input) + +/* Like alternative_input, but with a single output argument */ +#define alternative_io(oldinstr, newinstr, feature, output, input...) \ + asm volatile ("661:\n\t" oldinstr "\n662:\n" \ + ".section .altinstructions,\"a\"\n" \ + " .align 8\n" \ + " .quad 661b\n" /* label */ \ + " .quad 663f\n" /* new instruction */ \ + " .byte %c[feat]\n" /* feature bit */ \ + " .byte 662b-661b\n" /* sourcelen */ \ + " .byte 664f-663f\n" /* replacementlen */ \ + ".previous\n" \ + ".section .altinstr_replacement,\"ax\"\n" \ + "663:\n\t" newinstr "\n664:\n" /* replacement */ \ + ".previous" : output : [feat] "i" (feature), ##input) + +/* + * Alternative inline assembly for SMP. + * + * alternative_smp() takes two versions (SMP first, UP second) and is + * for more complex stuff such as spinlocks. + * + * The LOCK_PREFIX macro defined here replaces the LOCK and + * LOCK_PREFIX macros used everywhere in the source tree. + * + * SMP alternatives use the same data structures as the other + * alternatives and the X86_FEATURE_UP flag to indicate the case of a + * UP system running a SMP kernel. The existing apply_alternatives() + * works fine for patching a SMP kernel for UP. + * + * The SMP alternative tables can be kept after boot and contain both + * UP and SMP versions of the instructions to allow switching back to + * SMP at runtime, when hotplugging in a new CPU, which is especially + * useful in virtualized environments. + * + * The very common lock prefix is handled as special case in a + * separate table which is a pure address list without replacement ptr + * and size information. That keeps the table sizes small. + */ + +#ifdef CONFIG_SMP +#define alternative_smp(smpinstr, upinstr, args...) \ + asm volatile ("661:\n\t" smpinstr "\n662:\n" \ + ".section .smp_altinstructions,\"a\"\n" \ + " .align 8\n" \ + " .quad 661b\n" /* label */ \ + " .quad 663f\n" /* new instruction */ \ + " .byte 0x66\n" /* X86_FEATURE_UP */ \ + " .byte 662b-661b\n" /* sourcelen */ \ + " .byte 664f-663f\n" /* replacementlen */ \ + ".previous\n" \ + ".section .smp_altinstr_replacement,\"awx\"\n" \ + "663:\n\t" upinstr "\n" /* replacement */ \ + "664:\n\t.fill 662b-661b,1,0x42\n" /* space for original */ \ + ".previous" : args) + +#define LOCK_PREFIX \ + ".section .smp_locks,\"a\"\n" \ + " .align 8\n" \ + " .quad 661f\n" /* address */ \ + ".previous\n" \ + "661:\n\tlock; " + +#else /* ! CONFIG_SMP */ +#define alternative_smp(smpinstr, upinstr, args...) \ + asm volatile (upinstr : args) +#define LOCK_PREFIX "" +#endif + +#endif /* _X86_64_ALTERNATIVE_H */ |