From: Peter Zijlstra peterz@infradead.org
[ Upstream commit 9bb2ec608a209018080ca262f771e6a9ff203b6f ]
Update retpoline validation with the new CONFIG_RETPOLINE requirement of not having bare naked RET instructions.
Signed-off-by: Peter Zijlstra (Intel) peterz@infradead.org Signed-off-by: Borislav Petkov bp@suse.de Reviewed-by: Josh Poimboeuf jpoimboe@kernel.org Signed-off-by: Borislav Petkov bp@suse.de Signed-off-by: Sasha Levin sashal@kernel.org --- arch/x86/include/asm/nospec-branch.h | 6 ++++++ arch/x86/mm/mem_encrypt_boot.S | 2 ++ arch/x86/xen/xen-head.S | 1 + tools/objtool/check.c | 19 +++++++++++++------ 4 files changed, 22 insertions(+), 6 deletions(-)
diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h index da251a5645b0..f1a7ecd0a7c7 100644 --- a/arch/x86/include/asm/nospec-branch.h +++ b/arch/x86/include/asm/nospec-branch.h @@ -75,6 +75,12 @@ .popsection .endm
+/* + * (ab)use RETPOLINE_SAFE on RET to annotate away 'bare' RET instructions + * vs RETBleed validation. + */ +#define ANNOTATE_UNRET_SAFE ANNOTATE_RETPOLINE_SAFE + /* * JMP_NOSPEC and CALL_NOSPEC macros can be used instead of a simple * indirect jmp/call which may be susceptible to the Spectre variant 2 diff --git a/arch/x86/mm/mem_encrypt_boot.S b/arch/x86/mm/mem_encrypt_boot.S index d94dea450fa6..9de3d900bc92 100644 --- a/arch/x86/mm/mem_encrypt_boot.S +++ b/arch/x86/mm/mem_encrypt_boot.S @@ -66,6 +66,7 @@ SYM_FUNC_START(sme_encrypt_execute) pop %rbp
/* Offset to __x86_return_thunk would be wrong here */ + ANNOTATE_UNRET_SAFE ret int3 SYM_FUNC_END(sme_encrypt_execute) @@ -154,6 +155,7 @@ SYM_FUNC_START(__enc_copy) pop %r15
/* Offset to __x86_return_thunk would be wrong here */ + ANNOTATE_UNRET_SAFE ret int3 .L__enc_copy_end: diff --git a/arch/x86/xen/xen-head.S b/arch/x86/xen/xen-head.S index 13af6fe453e3..ffaa62167f6e 100644 --- a/arch/x86/xen/xen-head.S +++ b/arch/x86/xen/xen-head.S @@ -26,6 +26,7 @@ SYM_CODE_START(hypercall_page) .rept (PAGE_SIZE / 32) UNWIND_HINT_FUNC ANNOTATE_NOENDBR + ANNOTATE_UNRET_SAFE ret /* * Xen will write the hypercall page, and sort out ENDBR. diff --git a/tools/objtool/check.c b/tools/objtool/check.c index f66e4ac0af94..fbe41203fc9b 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -2030,8 +2030,9 @@ static int read_retpoline_hints(struct objtool_file *file) }
if (insn->type != INSN_JUMP_DYNAMIC && - insn->type != INSN_CALL_DYNAMIC) { - WARN_FUNC("retpoline_safe hint not an indirect jump/call", + insn->type != INSN_CALL_DYNAMIC && + insn->type != INSN_RETURN) { + WARN_FUNC("retpoline_safe hint not an indirect jump/call/ret", insn->sec, insn->offset); return -1; } @@ -3561,7 +3562,8 @@ static int validate_retpoline(struct objtool_file *file)
for_each_insn(file, insn) { if (insn->type != INSN_JUMP_DYNAMIC && - insn->type != INSN_CALL_DYNAMIC) + insn->type != INSN_CALL_DYNAMIC && + insn->type != INSN_RETURN) continue;
if (insn->retpoline_safe) @@ -3576,9 +3578,14 @@ static int validate_retpoline(struct objtool_file *file) if (!strcmp(insn->sec->name, ".init.text") && !module) continue;
- WARN_FUNC("indirect %s found in RETPOLINE build", - insn->sec, insn->offset, - insn->type == INSN_JUMP_DYNAMIC ? "jump" : "call"); + if (insn->type == INSN_RETURN) { + WARN_FUNC("'naked' return found in RETPOLINE build", + insn->sec, insn->offset); + } else { + WARN_FUNC("indirect %s found in RETPOLINE build", + insn->sec, insn->offset, + insn->type == INSN_JUMP_DYNAMIC ? "jump" : "call"); + }
warnings++; }