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| author | Peter Zijlstra <peterz@infradead.org> | 2021-12-04 14:43:44 +0100 |
|---|---|---|
| committer | Borislav Petkov <bp@suse.de> | 2021-12-09 13:32:25 +0100 |
| commit | e463a09af2f0677b9485a7e8e4e70b396b2ffb6f (patch) | |
| tree | 169cdec1cc953df3619ae2e08e662784211fbc24 /arch/x86/kernel/static_call.c | |
| parent | 26c44b776dba4ac692a0bf5a3836feb8a63fea6b (diff) | |
| download | lwn-e463a09af2f0677b9485a7e8e4e70b396b2ffb6f.tar.gz lwn-e463a09af2f0677b9485a7e8e4e70b396b2ffb6f.zip | |
x86: Add straight-line-speculation mitigation
Make use of an upcoming GCC feature to mitigate
straight-line-speculation for x86:
https://gcc.gnu.org/g:53a643f8568067d7700a9f2facc8ba39974973d3
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102952
https://bugs.llvm.org/show_bug.cgi?id=52323
It's built tested on x86_64-allyesconfig using GCC-12 and GCC-11.
Maintenance overhead of this should be fairly low due to objtool
validation.
Size overhead of all these additional int3 instructions comes to:
text data bss dec hex filename
22267751 6933356 2011368 31212475 1dc43bb defconfig-build/vmlinux
22804126 6933356 1470696 31208178 1dc32f2 defconfig-build/vmlinux.sls
Or roughly 2.4% additional text.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20211204134908.140103474@infradead.org
Diffstat (limited to 'arch/x86/kernel/static_call.c')
| -rw-r--r-- | arch/x86/kernel/static_call.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/arch/x86/kernel/static_call.c b/arch/x86/kernel/static_call.c index 9c407a33a774..531fb4cbb63f 100644 --- a/arch/x86/kernel/static_call.c +++ b/arch/x86/kernel/static_call.c @@ -17,6 +17,8 @@ enum insn_type { */ static const u8 xor5rax[] = { 0x66, 0x66, 0x48, 0x31, 0xc0 }; +static const u8 retinsn[] = { RET_INSN_OPCODE, 0xcc, 0xcc, 0xcc, 0xcc }; + static void __ref __static_call_transform(void *insn, enum insn_type type, void *func) { const void *emulate = NULL; @@ -42,8 +44,7 @@ static void __ref __static_call_transform(void *insn, enum insn_type type, void break; case RET: - code = text_gen_insn(RET_INSN_OPCODE, insn, func); - size = RET_INSN_SIZE; + code = &retinsn; break; } |