linux-kernel - Re: [PATCH] ftrace: x86: Fix a compile error about get_kernel

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <08422aab-f4a9-4f67-84ef-82ad3663b01f@163.com>
Date: Thu, 13 Feb 2025 18:25:41 +0800
From: Haiyue Wang <haiyuewa@....com>
To: Peter Zijlstra <peterz@...radead.org>,
 Sami Tolvanen <samitolvanen@...gle.com>
Cc: Steven Rostedt <rostedt@...dmis.org>,
 "Masami Hiramatsu (Google)" <mhiramat@...nel.org>,
 Gabriel de Perthuis <g2p.code@...il.com>, Mark Rutland
 <mark.rutland@....com>, Thomas Gleixner <tglx@...utronix.de>,
 Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
 Dave Hansen <dave.hansen@...ux.intel.com>, "H . Peter Anvin"
 <hpa@...or.com>, x86@...nel.org, linux-trace-kernel@...r.kernel.org,
 LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ftrace: x86: Fix a compile error about
 get_kernel_nofault()



On 2025/2/13 18:08, Peter Zijlstra wrote:
> On Wed, Feb 12, 2025 at 08:52:27AM -0800, Sami Tolvanen wrote:
>> On Tue, Feb 11, 2025 at 7:49 AM Steven Rostedt <rostedt@...dmis.org> wrote:
>>>
>>> On Tue, 11 Feb 2025 11:09:14 +0100
>>> Peter Zijlstra <peterz@...radead.org> wrote:
>>>
>>>> I was aiming my patch for x86/core, but if there's a reason to expedite
>>>> them, I can stick it in x86/urgent I suppose.
>>>>
>>>> Just need a reason -- what's this compile error nonsense about, my
>>>> kernels build just fine?
>>>
>>> Masami,
>>>
>>> Do you have a config that fails to build without this fix? If so, can you
>>> please reply with it, and then this can go in as a quick fix.
>>
>> x86 builds with both CONFIG_GENDWARFKSYMS and CONFIG_FUNCTION_TRACER
>> are broken without this fix. Here's how to reproduce:
>>
>> $ make defconfig
>> $ ./scripts/config -e DEBUG_INFO -e DEBUG_INFO_DWARF5 -e MODVERSIONS
>> -e GENDWARFKSYMS -e FUNCTION_TRACER
>> $ make olddefconfig && make -j
>> ...
>> In file included from ./arch/x86/include/asm/asm-prototypes.h:2,
>>                   from <stdin>:3:
>> ./arch/x86/include/asm/ftrace.h: In function ‘arch_ftrace_get_symaddr’:
>> ./arch/x86/include/asm/ftrace.h:46:21: error: implicit declaration of
>> function ‘get_kernel_nofault’ [-Wimplicit-function-declaration]
>>     46 |                 if (get_kernel_nofault(instr, (u32
>> *)(fentry_ip - ENDBR_INSN_SIZE)))
>> ...
> 
> It breaks much sooner, complaining about not having dwarf.h.. let me go
> figure out what package provides that :/
> 
> Anyway, thanks, I'll go see if my patch helps here.

It is header file include indirect :-)

https://lore.kernel.org/linux-trace-kernel/20250206131711.ea536f165d5b5980b3909acd@kernel.org/T/#t

File "asm-prototypes.h" is added to entry.S by 'scripts/Makefile.build',
adding the missed declaration header file can also fix the error:

  getasmexports =                                                        \
     { echo "\#include <linux/kernel.h>" ;                               \
       echo "\#include <linux/string.h>" ;                               \
+     echo "\#include <linux/uaccess.h>";                               \
       echo "\#include <asm/asm-prototypes.h>" ;                         \
       $(call getexportsymbols,EXPORT_SYMBOL(\1);) ; }