From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Borislav Petkov <bp@alien8.de>
Cc: Nick Desaulniers <ndesaulniers@google.com>,
Rong Chen <rong.a.chen@intel.com>,
kernel test robot <lkp@intel.com>,
"Li, Philip" <philip.li@intel.com>, x86-ml <x86@kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
clang-built-linux <clang-built-linux@googlegroups.com>,
Marco Elver <elver@google.com>
Subject: Re: [tip:x86/seves] BUILD SUCCESS WITH WARNING e6eb15c9ba3165698488ae5c34920eea20eaa38e
Date: Tue, 15 Sep 2020 16:02:31 -0500 [thread overview]
Message-ID: <20200915210231.ysaibtkeibdm4zps@treble> (raw)
In-Reply-To: <20200915204912.GA14436@zn.tnic>
On Tue, Sep 15, 2020 at 10:49:12PM +0200, Borislav Petkov wrote:
> On Tue, Sep 15, 2020 at 01:12:24PM -0700, Nick Desaulniers wrote:
> > 1 warning: objtool: ist_exc_vmm_communication()+0x12: unreachable instruction
>
> That looks interesting. So your .o has:
>
> 00000000000004c0 <ist_exc_vmm_communication>:
> 4c0: 55 push %rbp
> 4c1: 48 89 e5 mov %rsp,%rbp
> 4c4: 48 c7 c7 00 00 00 00 mov $0x0,%rdi
> 4cb: 31 c0 xor %eax,%eax
> 4cd: e8 00 00 00 00 callq 4d2 <ist_exc_vmm_communication+0x12>
> 4d2: 0f 0b ud2
> 4d4: 66 66 2e 0f 1f 84 00 data16 nopw %cs:0x0(%rax,%rax,1)
> 4db: 00 00 00 00
> 4df: 90 nop
If you disassemble with "objdump -dr" it shows the relocations:
00000000000004c0 <ist_exc_vmm_communication>:
4c0: 55 push %rbp
4c1: 48 89 e5 mov %rsp,%rbp
4c4: 48 c7 c7 00 00 00 00 mov $0x0,%rdi
4c7: R_X86_64_32S .rodata.str1.1+0x1ef
4cb: 31 c0 xor %eax,%eax
4cd: e8 00 00 00 00 callq 4d2 <ist_exc_vmm_communication+0x12>
4ce: R_X86_64_PLT32 panic-0x4
4d2: 0f 0b ud2
4d4: 66 66 2e 0f 1f 84 00 data16 nopw %cs:0x0(%rax,%rax,1)
4db: 00 00 00 00
4df: 90 nop
panic() is noreturn, so the compiler is enforcing the fact that it
doesn't return, by trapping if it does return.
I seem to remember that's caused by CONFIG_UBSAN_TRAP.
--
Josh
next prev parent reply other threads:[~2020-09-15 21:04 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-15 13:42 [tip:x86/seves] BUILD SUCCESS WITH WARNING e6eb15c9ba3165698488ae5c34920eea20eaa38e kernel test robot
2020-09-15 13:55 ` Borislav Petkov
2020-09-15 14:18 ` Rong Chen
2020-09-15 14:41 ` Borislav Petkov
2020-09-15 16:05 ` Borislav Petkov
2020-09-15 17:02 ` Josh Poimboeuf
2020-09-15 17:21 ` Borislav Petkov
2020-09-15 17:34 ` Borislav Petkov
2020-09-15 17:41 ` Nick Desaulniers
2020-09-15 18:01 ` Borislav Petkov
2020-09-15 18:04 ` Nick Desaulniers
2020-09-15 17:40 ` Nick Desaulniers
2020-09-15 18:09 ` Marco Elver
2020-09-16 8:30 ` peterz
2020-09-16 8:46 ` Marco Elver
2020-09-16 9:06 ` peterz
2020-09-16 9:33 ` Marco Elver
2020-09-16 18:22 ` Nick Desaulniers
2020-09-16 18:51 ` Marco Elver
2020-09-17 4:11 ` Fangrui Song
[not found] ` <333D40A0-4550-4309-9693-1ABA4AC75399@arm.com>
2020-09-17 11:04 ` Mark Rutland
2020-09-17 11:16 ` Daniel Kiss
2020-09-17 18:39 ` Josh Poimboeuf
2020-09-15 17:44 ` Nick Desaulniers
2020-09-15 20:12 ` Nick Desaulniers
2020-09-15 20:49 ` Borislav Petkov
2020-09-15 21:02 ` Josh Poimboeuf [this message]
2020-09-15 21:14 ` Borislav Petkov
2020-09-15 22:34 ` Nick Desaulniers
2020-09-16 7:03 ` Ilie Halip
2020-09-16 8:59 ` Marco Elver
2020-09-21 16:51 ` [tip: objtool/core] objtool: Ignore unreachable trap after call to noreturn functions tip-bot2 for Ilie Halip
2020-09-15 21:50 ` [tip:x86/seves] BUILD SUCCESS WITH WARNING e6eb15c9ba3165698488ae5c34920eea20eaa38e Arvind Sankar
2020-09-15 21:59 ` Nick Desaulniers
2020-09-15 22:44 ` Arvind Sankar
2020-09-16 11:34 ` Borislav Petkov
2020-09-16 18:28 ` Nick Desaulniers
2020-09-16 18:48 ` Borislav Petkov
2020-09-15 21:13 ` Nick Desaulniers
2020-09-15 21:28 ` Josh Poimboeuf
2020-09-15 23:35 ` Marco Elver
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