From 63f70270ccd981ce40a8ff58c03a8c2e97e368be Mon Sep 17 00:00:00 2001 From: Jeremy Fitzhardinge Date: Wed, 2 May 2007 19:27:14 +0200 Subject: [PATCH] i386: PARAVIRT: add common patching machinery Implement the actual patching machinery. paravirt_patch_default() contains the logic to automatically patch a callsite based on a few simple rules: - if the paravirt_op function is paravirt_nop, then patch nops - if the paravirt_op function is a jmp target, then jmp to it - if the paravirt_op function is callable and doesn't clobber too much for the callsite, call it directly paravirt_patch_default is suitable as a default implementation of paravirt_ops.patch, will remove most of the expensive indirect calls in favour of either a direct call or a pile of nops. Backends may implement their own patcher, however. There are several helper functions to help with this: paravirt_patch_nop nop out a callsite paravirt_patch_ignore leave the callsite as-is paravirt_patch_call patch a call if the caller and callee have compatible clobbers paravirt_patch_jmp patch in a jmp paravirt_patch_insns patch some literal instructions over the callsite, if they fit This patch also implements more direct patches for the native case, so that when running on native hardware many common operations are implemented inline. Signed-off-by: Jeremy Fitzhardinge Signed-off-by: Andi Kleen Cc: Rusty Russell Cc: Zachary Amsden Cc: Anthony Liguori Acked-by: Ingo Molnar --- include/asm-i386/paravirt.h | 12 ++++++++++++ 1 file changed, 12 insertions(+) (limited to 'include') diff --git a/include/asm-i386/paravirt.h b/include/asm-i386/paravirt.h index 8bfaf10d9961..4b3d50858670 100644 --- a/include/asm-i386/paravirt.h +++ b/include/asm-i386/paravirt.h @@ -248,6 +248,18 @@ extern struct paravirt_ops paravirt_ops; #define paravirt_alt(insn_string) \ _paravirt_alt(insn_string, "%c[paravirt_typenum]", "%c[paravirt_clobber]") +unsigned paravirt_patch_nop(void); +unsigned paravirt_patch_ignore(unsigned len); +unsigned paravirt_patch_call(void *target, u16 tgt_clobbers, + void *site, u16 site_clobbers, + unsigned len); +unsigned paravirt_patch_jmp(void *target, void *site, unsigned len); +unsigned paravirt_patch_default(u8 type, u16 clobbers, void *site, unsigned len); + +unsigned paravirt_patch_insns(void *site, unsigned len, + const char *start, const char *end); + + /* * This generates an indirect call based on the operation type number. * The type number, computed in PARAVIRT_PATCH, is derived from the -- cgit v1.2.3-59-g8ed1b