From: Josh Poimboeuf <jpoimboe@redhat.com> To: Linus Torvalds <torvalds@linux-foundation.org> Cc: Alexey Dobriyan <adobriyan@gmail.com>, Peter Anvin <h.peter.anvin@intel.com>, kernel test robot <xiaolong.ye@intel.com>, Ingo Molnar <mingo@kernel.org>, Thomas Gleixner <tglx@linutronix.de>, Andrew Lutomirski <luto@kernel.org>, Borislav Petkov <bp@alien8.de>, Brian Gerst <brgerst@gmail.com>, Denys Vlasenko <dvlasenk@redhat.com>, Peter Zijlstra <peterz@infradead.org>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, Peter Anvin <hpa@zytor.com>, tipbuild@zytor.com, LKP <lkp@01.org> Subject: Re: [lkp-robot] [x86/asm] 51bad67ffb: int3:#[##] Date: Tue, 15 May 2018 22:30:44 -0500 [thread overview] Message-ID: <20180516033044.odb74pdgcn5nacwb@treble> (raw) In-Reply-To: <CA+55aFwrT-BAvdujUonX5MvB=8GFopQJT4x6xMhtjNN2G0AxSw@mail.gmail.com> On Tue, May 15, 2018 at 04:05:33PM -0700, Linus Torvalds wrote: > I wonder if there's some way to add a test for "ENTRY only works in a code > section"? I suppose we could add a discardable annotation to the ENTRY macro and have objtool validate that it's in a text section. I'm not sure whether it's worth it, but I could do it if you think it's a good idea. Below is a tentative objtool patch which catches asm code falling through to INT3 padding, though objtool is 64-bit only so there won't be any 32-bit coverage. It found zero hits on my config. I'll clean it up and submit it tomorrow-ish. diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S index 8344dd2f310a..3ed8cec6e765 100644 --- a/arch/x86/kernel/head_64.S +++ b/arch/x86/kernel/head_64.S @@ -285,11 +285,9 @@ ENTRY(early_idt_handler_array) .endif pushq $i # 72(%rsp) Vector number jmp early_idt_handler_common - UNWIND_HINT_IRET_REGS i = i + 1 .fill early_idt_handler_array + i*EARLY_IDT_HANDLER_SIZE - ., 1, 0xcc .endr - UNWIND_HINT_IRET_REGS offset=16 END(early_idt_handler_array) early_idt_handler_common: diff --git a/tools/objtool/arch.h b/tools/objtool/arch.h index b0d7dc3d71b5..6eb058a8ac00 100644 --- a/tools/objtool/arch.h +++ b/tools/objtool/arch.h @@ -33,7 +33,8 @@ #define INSN_STACK 8 #define INSN_BUG 9 #define INSN_NOP 10 -#define INSN_OTHER 11 +#define INSN_PADDING 11 +#define INSN_OTHER 12 #define INSN_LAST INSN_OTHER enum op_dest_type { diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c index 7e86a743f851..82b41bb93c02 100644 --- a/tools/objtool/arch/x86/decode.c +++ b/tools/objtool/arch/x86/decode.c @@ -421,7 +421,7 @@ int arch_decode_instruction(struct elf *elf, struct section *sec, case 0xcc: /* int3: used for asm function padding by the __ALIGN macro */ - *type = INSN_NOP; + *type = INSN_PADDING; break; case 0xe3: diff --git a/tools/objtool/check.c b/tools/objtool/check.c index f4bbce838433..8a83a0d1693a 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -1936,6 +1936,14 @@ static int validate_branch(struct objtool_file *file, struct instruction *first, } return 0; + case INSN_PADDING: + if (!func) { + WARN_FUNC("code falls through to INT3 padding", + insn->sec, insn->offset); + return 1; + } + break; + case INSN_STACK: if (update_insn_state(insn, &state)) return 1; @@ -2032,7 +2040,8 @@ static bool ignore_unreachable_insn(struct instruction *insn) { int i; - if (insn->ignore || insn->type == INSN_NOP) + if (insn->ignore || insn->type == INSN_NOP || + insn->type == INSN_PADDING) return true; /*
WARNING: multiple messages have this Message-ID (diff)
From: Josh Poimboeuf <jpoimboe@redhat.com> To: lkp@lists.01.org Subject: Re: [lkp-robot] [x86/asm] 51bad67ffb: int3:#[##] Date: Tue, 15 May 2018 22:30:44 -0500 [thread overview] Message-ID: <20180516033044.odb74pdgcn5nacwb@treble> (raw) In-Reply-To: <CA+55aFwrT-BAvdujUonX5MvB=8GFopQJT4x6xMhtjNN2G0AxSw@mail.gmail.com> [-- Attachment #1: Type: text/plain, Size: 2760 bytes --] On Tue, May 15, 2018 at 04:05:33PM -0700, Linus Torvalds wrote: > I wonder if there's some way to add a test for "ENTRY only works in a code > section"? I suppose we could add a discardable annotation to the ENTRY macro and have objtool validate that it's in a text section. I'm not sure whether it's worth it, but I could do it if you think it's a good idea. Below is a tentative objtool patch which catches asm code falling through to INT3 padding, though objtool is 64-bit only so there won't be any 32-bit coverage. It found zero hits on my config. I'll clean it up and submit it tomorrow-ish. diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S index 8344dd2f310a..3ed8cec6e765 100644 --- a/arch/x86/kernel/head_64.S +++ b/arch/x86/kernel/head_64.S @@ -285,11 +285,9 @@ ENTRY(early_idt_handler_array) .endif pushq $i # 72(%rsp) Vector number jmp early_idt_handler_common - UNWIND_HINT_IRET_REGS i = i + 1 .fill early_idt_handler_array + i*EARLY_IDT_HANDLER_SIZE - ., 1, 0xcc .endr - UNWIND_HINT_IRET_REGS offset=16 END(early_idt_handler_array) early_idt_handler_common: diff --git a/tools/objtool/arch.h b/tools/objtool/arch.h index b0d7dc3d71b5..6eb058a8ac00 100644 --- a/tools/objtool/arch.h +++ b/tools/objtool/arch.h @@ -33,7 +33,8 @@ #define INSN_STACK 8 #define INSN_BUG 9 #define INSN_NOP 10 -#define INSN_OTHER 11 +#define INSN_PADDING 11 +#define INSN_OTHER 12 #define INSN_LAST INSN_OTHER enum op_dest_type { diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c index 7e86a743f851..82b41bb93c02 100644 --- a/tools/objtool/arch/x86/decode.c +++ b/tools/objtool/arch/x86/decode.c @@ -421,7 +421,7 @@ int arch_decode_instruction(struct elf *elf, struct section *sec, case 0xcc: /* int3: used for asm function padding by the __ALIGN macro */ - *type = INSN_NOP; + *type = INSN_PADDING; break; case 0xe3: diff --git a/tools/objtool/check.c b/tools/objtool/check.c index f4bbce838433..8a83a0d1693a 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -1936,6 +1936,14 @@ static int validate_branch(struct objtool_file *file, struct instruction *first, } return 0; + case INSN_PADDING: + if (!func) { + WARN_FUNC("code falls through to INT3 padding", + insn->sec, insn->offset); + return 1; + } + break; + case INSN_STACK: if (update_insn_state(insn, &state)) return 1; @@ -2032,7 +2040,8 @@ static bool ignore_unreachable_insn(struct instruction *insn) { int i; - if (insn->ignore || insn->type == INSN_NOP) + if (insn->ignore || insn->type == INSN_NOP || + insn->type == INSN_PADDING) return true; /*
next prev parent reply other threads:[~2018-05-16 3:30 UTC|newest] Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-05-15 8:00 [lkp-robot] [x86/asm] 51bad67ffb: int3:#[##] kernel test robot 2018-05-15 8:00 ` kernel test robot 2018-05-15 21:07 ` Alexey Dobriyan 2018-05-15 21:07 ` Alexey Dobriyan 2018-05-15 21:25 ` Anvin, H Peter 2018-05-15 21:43 ` Alexey Dobriyan 2018-05-15 21:43 ` Alexey Dobriyan 2018-05-15 22:22 ` Josh Poimboeuf 2018-05-15 22:22 ` Josh Poimboeuf 2018-05-15 22:26 ` Thomas Gleixner 2018-05-15 22:26 ` Thomas Gleixner 2018-05-15 22:28 ` Linus Torvalds 2018-05-15 22:28 ` Linus Torvalds 2018-05-15 22:43 ` Josh Poimboeuf 2018-05-15 22:43 ` Josh Poimboeuf 2018-05-15 22:52 ` Linus Torvalds 2018-05-15 22:52 ` Linus Torvalds 2018-05-15 23:05 ` Linus Torvalds 2018-05-15 23:05 ` Linus Torvalds 2018-05-16 3:30 ` Josh Poimboeuf [this message] 2018-05-16 3:30 ` Josh Poimboeuf 2018-05-17 13:49 ` [PATCH] objtool: Detect assembly code falling through to INT3 padding Josh Poimboeuf 2018-05-17 13:49 ` Josh Poimboeuf 2018-05-17 14:01 ` Peter Zijlstra 2018-05-17 14:01 ` Peter Zijlstra 2018-05-18 7:24 ` Ingo Molnar 2018-05-18 7:24 ` Ingo Molnar 2018-05-18 7:18 ` Ingo Molnar 2018-05-18 7:18 ` Ingo Molnar 2018-05-18 7:27 ` H. Peter Anvin 2018-05-18 16:06 ` Borislav Petkov 2018-05-18 16:06 ` Borislav Petkov 2018-05-18 7:27 ` Ingo Molnar 2018-05-18 7:27 ` Ingo Molnar 2018-05-18 17:51 ` Alexey Dobriyan 2018-05-18 17:51 ` Alexey Dobriyan 2018-05-19 8:18 ` hpa 2018-05-19 7:00 ` "interesting" entry in hibernation code was Re: [lkp-robot] [x86/asm] 51bad67ffb: int3:#[##] Pavel Machek 2018-05-19 7:00 ` Pavel Machek 2018-05-19 8:35 ` Rafael J. Wysocki 2018-05-19 8:35 ` Rafael J. Wysocki 2018-05-18 7:15 ` Ingo Molnar 2018-05-18 7:15 ` Ingo Molnar 2018-05-15 22:25 ` Thomas Gleixner 2018-05-15 22:25 ` Thomas Gleixner 2018-05-15 22:29 ` Andy Lutomirski 2018-05-15 22:29 ` Andy Lutomirski 2018-05-15 22:27 ` Linus Torvalds 2018-05-15 22:27 ` Linus Torvalds 2018-05-15 22:50 ` Alexey Dobriyan 2018-05-15 22:50 ` Alexey Dobriyan 2018-05-15 22:58 ` [PATCH v2] x86/asm: Pad assembly functions with INT3 instructions Alexey Dobriyan 2018-05-15 22:58 ` Alexey Dobriyan 2018-05-15 23:28 ` Linus Torvalds 2018-05-15 23:28 ` Linus Torvalds 2018-05-18 7:36 ` Ingo Molnar 2018-05-18 7:36 ` Ingo Molnar 2018-05-18 13:02 ` Josh Poimboeuf 2018-05-18 13:02 ` Josh Poimboeuf 2018-05-18 17:34 ` Alexey Dobriyan 2018-05-18 17:34 ` Alexey Dobriyan
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