On November 24, 2022 3:51:53 AM PST, Hou Wenlong <[email protected]> wrote: >Similar to the alternative patching, use relative reference for original >instruction rather than absolute one, which saves 8 bytes for one entry >on x86_64. And it could generate R_X86_64_PC32 relocation instead of >R_X86_64_64 relocation, which also reduces relocation metadata on >relocatable builds. And the alignment could be hard coded to be 4 now. > >Signed-off-by: Hou Wenlong <[email protected]> >--- > arch/x86/include/asm/paravirt.h | 10 +++++----- > arch/x86/include/asm/paravirt_types.h | 8 ++++---- > arch/x86/kernel/alternative.c | 8 +++++--- > 3 files changed, 14 insertions(+), 12 deletions(-) > >diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h >index 2851bc2339d5..e56065ea73f2 100644 >--- a/arch/x86/include/asm/paravirt.h >+++ b/arch/x86/include/asm/paravirt.h >@@ -735,16 +735,16 @@ extern void default_banner(void); > > #else /* __ASSEMBLY__ */ > >-#define _PVSITE(ptype, ops, word, algn) \ >+#define _PVSITE(ptype, ops) \ > 771:; \ > ops; \ > 772:; \ > .pushsection .parainstructions,"a"; \ >- .align algn; \ >- word 771b; \ >+ .align 4; \ >+ .long 771b-.; \ > .byte ptype; \ > .byte 772b-771b; \ >- _ASM_ALIGN; \ >+ .align 4; \ > .popsection > > >@@ -752,7 +752,7 @@ extern void default_banner(void); > #ifdef CONFIG_PARAVIRT_XXL > > #define PARA_PATCH(off) ((off) / 8) >-#define PARA_SITE(ptype, ops) _PVSITE(ptype, ops, .quad, 8) >+#define PARA_SITE(ptype, ops) _PVSITE(ptype, ops) > #define PARA_INDIRECT(addr) *addr(%rip) > > #ifdef CONFIG_DEBUG_ENTRY >diff --git a/arch/x86/include/asm/paravirt_types.h >b/arch/x86/include/asm/paravirt_types.h >index 8c1da419260f..68952ae07a3f 100644 >--- a/arch/x86/include/asm/paravirt_types.h >+++ b/arch/x86/include/asm/paravirt_types.h >@@ -5,7 +5,7 @@ > #ifndef __ASSEMBLY__ > /* These all sit in the .parainstructions section to tell us what to patch. */ > struct paravirt_patch_site { >- u8 *instr; /* original instructions */ >+ s32 instr_offset; /* original instructions */ > u8 type; /* type of this instruction */ > u8 len; /* length of original instruction */ > }; >@@ -273,11 +273,11 @@ extern struct paravirt_patch_template pv_ops; > #define _paravirt_alt(insn_string, type) \ > "771:\n\t" insn_string "\n" "772:\n" \ > ".pushsection .parainstructions,\"a\"\n" \ >- _ASM_ALIGN "\n" \ >- _ASM_PTR " 771b\n" \ >+ " .align 4\n" \ >+ " .long 771b-.\n" \ > " .byte " type "\n" \ > " .byte 772b-771b\n" \ >- _ASM_ALIGN "\n" \ >+ " .align 4\n" \ > ".popsection\n" > > /* Generate patchable code, with the default asm parameters. */ >diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c >index 111b809f0ac2..6eea563a098d 100644 >--- a/arch/x86/kernel/alternative.c >+++ b/arch/x86/kernel/alternative.c >@@ -1232,20 +1232,22 @@ void __init_or_module apply_paravirt(struct >paravirt_patch_site *start, > { > struct paravirt_patch_site *p; > char insn_buff[MAX_PATCH_LEN]; >+ u8 *instr; > > for (p = start; p < end; p++) { > unsigned int used; > >+ instr = (u8 *)&p->instr_offset + p->instr_offset; > BUG_ON(p->len > MAX_PATCH_LEN); > /* prep the buffer with the original instructions */ >- memcpy(insn_buff, p->instr, p->len); >- used = paravirt_patch(p->type, insn_buff, (unsigned >long)p->instr, p->len); >+ memcpy(insn_buff, instr, p->len); >+ used = paravirt_patch(p->type, insn_buff, (unsigned long)instr, >p->len); > > BUG_ON(used > p->len); > > /* Pad the rest with nops */ > add_nops(insn_buff + used, p->len - used); >- text_poke_early(p->instr, insn_buff, p->len); >+ text_poke_early(instr, insn_buff, p->len); > } > } > extern struct paravirt_patch_site __start_parainstructions[],
Any reason that you couldn't use the same patching code? _______________________________________________ Virtualization mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/virtualization
