linux-kernel - Re: [RFC PATCH v3] tools/x86: add kcpuid tool to show raw CPU features

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Date:   Thu, 19 Nov 2020 15:20:55 +0800
From:   Feng Tang <feng.tang@...el.com>
To:     Borislav Petkov <bp@...en8.de>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H . Peter Anvin" <hpa@...or.com>,
        Dave Hansen <dave.hansen@...el.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org, nivedita@...m.mit.edu,
        thomas.lendacky@....com, yazen.ghannam@....com, wei.huang2@....com
Subject: Re: [RFC PATCH v3] tools/x86: add kcpuid tool to show raw CPU
 features

Hi Borislav,

Thanks for reviewing and trying.

On Wed, Nov 18, 2020 at 08:15:29PM +0100, Borislav Petkov wrote:
> On Thu, Oct 22, 2020 at 01:21:23PM +0800, Feng Tang wrote:
> > diff --git a/tools/arch/x86/kcpuid/kcpuid.c b/tools/arch/x86/kcpuid/kcpuid.c
> > new file mode 100644
> > index 0000000..9bd35b7
> > --- /dev/null
> > +++ b/tools/arch/x86/kcpuid/kcpuid.c
> > @@ -0,0 +1,618 @@
> > +// SPDX-License-Identifier: GPL-2.0
> 
> You need here:
> 
> #define _GNU_SOURCE

Thanks for the fix.


> otherwise:
> 
> cc -Wextra -O2 -Wall -I../../../include -o kcpuid kcpuid.c 
> kcpuid.c: In function ‘parse_line’:
> kcpuid.c:324:6: warning: implicit declaration of function ‘strcasestr’; did you mean ‘strcasecmp’? [-Wimplicit-function-declaration]
>   324 |  if (strcasestr(buf, "EAX"))
>       |      ^~~~~~~~~~
>       |      strcasecmp
 
 
> Also, options text needs fixing:
> 
>   usage: kcpuid [-abdfhr] [-l leaf] [-s subleaf]
>         -a|--all             Show info of all CPUID leafs and subleafs(default on)
>         -b|--bitflags        Show boolean flags only
>         -d|--detail          Show details of the flag/fields
>         -f|--flags           Show boolean flags only
> 
> that f is user_csv, above in the "usage" line too.
> 
>         -h|--help            Show usage info
>         -l|--leaf=index      Specify the leaf you want to check
>         -r|--raw             Show raw cpuid data
>         -s|--subleaf=sub     Specify the subleaf you want to check
 
Will fix.

> > +/*
> > + * Parse text file, and construct the array of all CPUID leafs and subleafs
> > + */
> > +static void parse_text(void)
> > +{
> > +	FILE *file;
> > +	char *filename, *line = NULL;
> 
> Do here:
> 
> 	char *filename = def_csv;
> 
> > +	size_t len = 0;
> > +	int ret;
> > +
> > +	if (show_raw)
> > +		return;
> > +
> > +	filename = user_csv ? user_csv : def_csv;
> 
> And now you do:
> 
> 	if (user_csv)
> 		filename = user_csv;

Ok, will change.

 
> But something's not working still. I've added debug output and it chokes
> on the test data:
> 
> $ ./kcpuid -f cpuid.csv 
> This platform has 51 CPUID leafs and subleafs.
> 
> parse_text: filename: cpuid.csv
> open
> parsing [# The basic row format is:
> ]parsing [# LEAF,SUBLEAF,register_name,bits,short name,long description
> ]parsing [
> ]parsing [# Leaf 00H
> ]parsing [         0,    0,  EAX,   31:0, max_basic_leafs,  Max input value for supported subleafs
> ]parsing [# Leaf 01H
> ]parsing [         1,    0,  ECX,     28, avx,  AVX instruction supported
> ]parsing [         1,    0,  ECX,     29, f16c,  16-bit floating-point conversion instruction supported
> ]parsing [         1,    0,  ECX,     30, rdrand,  RDRAND instruction supported
> ]parsing [
> ]parsing [#
> ]parsing [# !!! Test data for testing different options, will be updated in formal version
> ]parsing [#
> ]parsing [         4,    0,  ECX,      1, aaa,  AAA
> Segmentation fault

I just tried the patch on one Debian 9 and 2 Ubuntus (16.04 & 20.10) with
different gcc versions, and haven't reproduced it yet. What's your distro
and gcc version? I will try to reproduce. 

One thing I doubted is the getline() in parse_text() needs a accompany
free() according to its man page, but it can be added after the loop.

Anyway I attached one debug verison kcpuid.c which prints more info, thanks.

- Feng

> Thx.
> 
> -- 
> Regards/Gruss,
>     Boris.
> 
> https://people.kernel.org/tglx/notes-about-netiquette

View attachment "kcpuid.c" of type "text/x-csrc" (12900 bytes)