From 9689b1acab71adc2bcc07b3e23c141907dd9ecb8 Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Fri, 9 Apr 2021 09:17:04 +0200 Subject: [PATCH] x86: limit amount of INT3 in IND_THUNK_* MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit There's no point having every replacement variant to also specify the INT3 - just have it once in the base macro. When patching, NOPs will get inserted, which are fine to speculate through (until reaching the INT3). Signed-off-by: Jan Beulich Acked-by: Roger Pau Monné --- xen/arch/x86/indirect-thunk.S | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/xen/arch/x86/indirect-thunk.S b/xen/arch/x86/indirect-thunk.S index 7392aee127..a090b35dcf 100644 --- a/xen/arch/x86/indirect-thunk.S +++ b/xen/arch/x86/indirect-thunk.S @@ -11,6 +11,9 @@ #include +/* Don't transform the "ret" further down. */ +.purgem ret + .macro IND_THUNK_RETPOLINE reg:req call 2f 1: @@ -24,12 +27,10 @@ .macro IND_THUNK_LFENCE reg:req lfence jmp *%\reg - int3 /* Halt straight-line speculation */ .endm .macro IND_THUNK_JMP reg:req jmp *%\reg - int3 /* Halt straight-line speculation */ .endm /* @@ -44,6 +45,8 @@ ENTRY(__x86_indirect_thunk_\reg) __stringify(IND_THUNK_LFENCE \reg), X86_FEATURE_IND_THUNK_LFENCE, \ __stringify(IND_THUNK_JMP \reg), X86_FEATURE_IND_THUNK_JMP + int3 /* Halt straight-line speculation */ + .size __x86_indirect_thunk_\reg, . - __x86_indirect_thunk_\reg .type __x86_indirect_thunk_\reg, @function .endm -- 2.30.2