On 12. 07. 22, 20:39, Greg Kroah-Hartman wrote:
From: Peter Zijlstra peterz@infradead.org
commit 9bb2ec608a209018080ca262f771e6a9ff203b6f upstream.
Update retpoline validation with the new CONFIG_RETPOLINE requirement of not having bare naked RET instructions.
Hi,
this breaks compilation on i386:
arch/x86/kernel/../../x86/xen/xen-head.S:35: Error: no such
instruction: `annotate_unret_safe'
Config: https://raw.githubusercontent.com/openSUSE/kernel-source/stable/config/i386/...
And yeah, upstream¹⁾ is affected too.
¹⁾I am at commit b047602d579b4fb028128a525f056bbdc890e7f0.
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: Thadeu Lima de Souza Cascardo cascardo@canonical.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.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(-)
--- a/arch/x86/include/asm/nospec-branch.h +++ b/arch/x86/include/asm/nospec-branch.h @@ -76,6 +76,12 @@ .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
- attack.
--- 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:
--- 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
- Xen will write the hypercall page, and sort out ENDBR.
--- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -2114,8 +2114,9 @@ static int read_retpoline_hints(struct o } 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;@@ -3648,7 +3649,8 @@ static int validate_retpoline(struct obj 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) @@ -3663,9 +3665,14 @@ static int validate_retpoline(struct obj 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++; }