From: Peter Zijlstra <peterz@infradead.org>
To: x86@kernel.org, joao@overdrivepizza.com, hjl.tools@gmail.com,
jpoimboe@redhat.com, andrew.cooper3@citrix.com
Cc: linux-kernel@vger.kernel.org, ndesaulniers@google.com,
keescook@chromium.org, samitolvanen@google.com
Subject: Re: [RFC][PATCH 3/6] x86: Add ENDBR to IRET-to-Self
Date: Mon, 22 Nov 2021 19:09:47 +0100 [thread overview]
Message-ID: <20211122180947.GA721624@worktop.programming.kicks-ass.net> (raw)
In-Reply-To: <20211122170805.149482391@infradead.org>
On Mon, Nov 22, 2021 at 06:03:04PM +0100, Peter Zijlstra wrote:
> The IRET-to-Self chunks trigger forward code references without ENDBR,
> fix that.
Andy corrected me, IRET doesn't take ENBR, the alternative is the below.
---
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -1316,7 +1316,6 @@ SYM_CODE_START(asm_exc_nmi)
iretq /* continues at repeat_nmi below */
UNWIND_HINT_IRET_REGS entry=0
1:
- ENDBR
#endif
repeat_nmi:
--- a/arch/x86/include/asm/sync_core.h
+++ b/arch/x86/include/asm/sync_core.h
@@ -6,7 +6,6 @@
#include <asm/processor.h>
#include <asm/cpufeature.h>
#include <asm/special_insns.h>
-#include <asm/ibt.h>
#ifdef CONFIG_X86_32
static inline void iret_to_self(void)
@@ -35,7 +34,6 @@ static inline void iret_to_self(void)
"pushq $1f\n\t"
"iretq\n\t"
"1:"
- ASM_ENDBR
: "=&r" (tmp), ASM_CALL_CONSTRAINT : : "cc", "memory");
}
#endif /* CONFIG_X86_32 */
--- a/tools/objtool/arch/x86/decode.c
+++ b/tools/objtool/arch/x86/decode.c
@@ -598,6 +598,7 @@ int arch_decode_instruction(struct objto
op->dest.type = OP_DEST_REG;
op->dest.reg = CFI_SP;
}
+ *type = INSN_IRET;
break;
}
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -3587,7 +3587,7 @@ static int validate_ibt_reloc(struct obj
static void validate_ibt_insn(struct objtool_file *file, struct instruction *insn)
{
struct reloc *reloc = insn_reloc(file, insn);
- struct instruction *target;
+ struct instruction *target, *n;
unsigned long offset;
if (!reloc)
@@ -3599,8 +3599,16 @@ static void validate_ibt_insn(struct obj
offset = reloc->sym->offset + reloc->addend;
target = find_insn(file, reloc->sym->sec, offset);
- if (target && insn->func == target->func && target->this_ip)
- return;
+ if (target && insn->func == target->func) {
+ if (target->this_ip)
+ return;
+
+ for (n = insn; n->offset <= target->offset;
+ n = next_insn_same_func(file, n)) {
+ if (n->type == INSN_IRET)
+ return;
+ }
+ }
WARN_FUNC("relocation to !ENDBR: %s+0x%lx",
insn->sec, insn->offset,
--- a/tools/objtool/include/objtool/arch.h
+++ b/tools/objtool/include/objtool/arch.h
@@ -27,6 +27,7 @@ enum insn_type {
INSN_STD,
INSN_CLD,
INSN_ENDBR,
+ INSN_IRET,
INSN_OTHER,
};
next prev parent reply other threads:[~2021-11-22 18:10 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-22 17:03 [RFC][PATCH 0/6] x86: Kernel IBT beginnings Peter Zijlstra
2021-11-22 17:03 ` [RFC][PATCH 1/6] x86: Annotate _THIS_IP_ Peter Zijlstra
2021-11-23 13:53 ` Mark Rutland
2021-11-23 14:14 ` Peter Zijlstra
2021-11-24 18:18 ` Josh Poimboeuf
2021-11-22 17:03 ` [RFC][PATCH 2/6] x86: Base IBT bits Peter Zijlstra
2022-02-08 23:32 ` Kees Cook
2021-11-22 17:03 ` [RFC][PATCH 3/6] x86: Add ENDBR to IRET-to-Self Peter Zijlstra
2021-11-22 18:09 ` Peter Zijlstra [this message]
2022-02-08 23:33 ` Kees Cook
2021-11-22 17:03 ` [RFC][PATCH 4/6] objtool: Read the _THIS_IP_ hints Peter Zijlstra
2021-11-22 17:03 ` [RFC][PATCH 5/6] x86: Sprinkle ENDBR dust Peter Zijlstra
2021-11-23 14:00 ` Mark Rutland
2021-11-23 14:21 ` Peter Zijlstra
2022-02-08 23:38 ` Kees Cook
2021-11-22 17:03 ` [RFC][PATCH 6/6] objtool: Add IBT validation / fixups Peter Zijlstra
2021-11-24 19:30 ` Josh Poimboeuf
2022-02-08 23:43 ` Kees Cook
2022-02-09 5:09 ` Josh Poimboeuf
2022-02-09 11:41 ` Peter Zijlstra
2022-02-09 11:45 ` Peter Zijlstra
2021-12-24 2:05 ` joao
2022-02-08 23:42 ` Kees Cook
2022-02-09 2:21 ` Joao Moreira
2022-02-09 4:05 ` Kees Cook
2022-02-09 5:18 ` Joao Moreira
2022-02-11 13:38 ` Peter Zijlstra
2022-02-14 21:38 ` Sami Tolvanen
2022-02-14 22:25 ` Peter Zijlstra
2022-02-15 16:56 ` Sami Tolvanen
2022-02-15 20:03 ` Kees Cook
2022-02-15 21:05 ` Peter Zijlstra
2022-02-15 23:05 ` Kees Cook
2022-02-15 23:38 ` Joao Moreira
2022-02-16 12:24 ` Peter Zijlstra
2022-02-15 20:53 ` Peter Zijlstra
2022-02-15 22:45 ` Joao Moreira
2022-02-16 0:57 ` Andrew Cooper
2022-03-02 3:06 ` Peter Collingbourne
2022-03-02 3:32 ` Joao Moreira
2022-06-08 17:53 ` Fāng-ruì Sòng
2022-06-09 0:05 ` Sami Tolvanen
2021-11-23 7:58 ` [RFC][PATCH 0/6] x86: Kernel IBT beginnings Christoph Hellwig
2021-11-23 9:02 ` Peter Zijlstra
2022-02-08 23:48 ` Kees Cook
2022-02-09 0:09 ` Nick Desaulniers
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