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authorJeremy Fitzhardinge <jeremy@goop.org>2007-05-02 19:27:14 +0200
committerAndi Kleen <andi@basil.nowhere.org>2007-05-02 19:27:14 +0200
commit63f70270ccd981ce40a8ff58c03a8c2e97e368be (patch)
tree7ffe766f25007845c99cfc337365c3006a153b83 /arch/i386/kernel/alternative.c
parent294688c028e80fd467cdd22da79f62c5f311eaf5 (diff)
[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 <jeremy@xensource.com> Signed-off-by: Andi Kleen <ak@suse.de> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Zachary Amsden <zach@vmware.com> Cc: Anthony Liguori <anthony@codemonkey.ws> Acked-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/i386/kernel/alternative.c')
-rw-r--r--arch/i386/kernel/alternative.c5
1 files changed, 4 insertions, 1 deletions
diff --git a/arch/i386/kernel/alternative.c b/arch/i386/kernel/alternative.c
index dae3ded9041..c5d037c6095 100644
--- a/arch/i386/kernel/alternative.c
+++ b/arch/i386/kernel/alternative.c
@@ -336,11 +336,14 @@ void apply_paravirt(struct paravirt_patch_site *start,
used = paravirt_ops.patch(p->instrtype, p->clobbers, p->instr,
p->len);
+ BUG_ON(used > p->len);
+
/* Pad the rest with nops */
nop_out(p->instr + used, p->len - used);
}
- /* Sync to be conservative, in case we patched following instructions */
+ /* Sync to be conservative, in case we patched following
+ * instructions */
sync_core();
}
extern struct paravirt_patch_site __start_parainstructions[],