OrgACRN
/
acrn-kernel
mirror of https://github.com/projectacrn/acrn-kernel.git
1
0
Fork 0
Code Issues Releases Wiki Activity

x86,retpoline: Be sure to emit INT3 after JMP *%\reg 

Both AMD and Intel recommend using INT3 after an indirect JMP. Make sure
to emit one when rewriting the retpoline JMP irrespective of compiler
SLS options or even CONFIG_SLS.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Link: https://lkml.kernel.org/r/Yxm+QkFPOhrVSH6q@hirez.programming.kicks-ass.net
This commit is contained in:
Peter Zijlstra 2022-09-08 12:04:50 +02:00
parent bc12b70f7d
commit 8c03af3e09
2 changed files with 12 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
arch/x86/kernel/alternative.c
View File

@ -453,6 +453,15 @@ static int patch_retpoline(void *addr, struct insn *insn, u8 *bytes)
return ret;
i += ret;
/*
* The compiler is supposed to EMIT an INT3 after every unconditional
* JMP instruction due to AMD BTC. However, if the compiler is too old
* or SLS isn't enabled, we still need an INT3 after indirect JMPs
* even on Intel.
*/
if (op == JMP32_INSN_OPCODE && i < insn->length)
bytes[i++] = INT3_INSN_OPCODE;
for (; i < insn->length;)
bytes[i++] = BYTES_NOP1;

4
arch/x86/net/bpf_jit_comp.c
View File

@ -419,7 +419,9 @@ static void emit_indirect_jump(u8 **pprog, int reg, u8 *ip)
OPTIMIZER_HIDE_VAR(reg);
emit_jump(&prog, &__x86_indirect_thunk_array[reg], ip);
} else {
EMIT2(0xFF, 0xE0 + reg);
EMIT2(0xFF, 0xE0 + reg); /* jmp *%\reg */
if (IS_ENABLED(CONFIG_RETPOLINE) || IS_ENABLED(CONFIG_SLS))
EMIT1(0xCC); /* int3 */
}
*pprog = prog;