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| Started by | "H. Peter Anvin" <hpa@zytor.com> |
|---|---|
| First post | 2017-02-14 19:20 +0100 |
| Last post | 2017-02-28 09:40 +0100 |
| Articles | 4 — 3 participants |
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Re: [PATCH 3/6] x86/cpu: proc - remove "wp" status line in cpuinfo "H. Peter Anvin" <hpa@zytor.com> - 2017-02-14 19:20 +0100
Re: [PATCH 3/6] x86/cpu: proc - remove "wp" status line in cpuinfo Borislav Petkov <bp@alien8.de> - 2017-02-14 19:40 +0100
Re: [PATCH 3/6] x86/cpu: proc - remove "wp" status line in cpuinfo Mathias Krause <minipli@googlemail.com> - 2017-02-14 22:50 +0100
Re: [PATCH 3/6] x86/cpu: proc - remove "wp" status line in cpuinfo Mathias Krause <minipli@googlemail.com> - 2017-02-28 09:40 +0100
| From | "H. Peter Anvin" <hpa@zytor.com> |
|---|---|
| Date | 2017-02-14 19:20 +0100 |
| Subject | Re: [PATCH 3/6] x86/cpu: proc - remove "wp" status line in cpuinfo |
| Message-ID | <taPRL-5dX-9@gated-at.bofh.it> |
On 02/12/17 13:12, Mathias Krause wrote:
> As of commit a5c2a893dbd4 ("x86, 386 removal: Remove
> CONFIG_X86_WP_WORKS_OK") the kernel won't boot if CR0.WP isn't working
> correctly. This makes a process reading this file always see "wp : yes"
> here -- otherwise there would be no process to begin with ;)
>
> As this status line in /proc/cpuinfo serves no purpose for quite some
> time now, get rid of it.
>
> Cc: Borislav Petkov <bp@alien8.de>
> Cc: H. Peter Anvin <hpa@linux.intel.com>
> Signed-off-by: Mathias Krause <minipli@googlemail.com>
> ---
> arch/x86/kernel/cpu/proc.c | 6 ++----
> 1 file changed, 2 insertions(+), 4 deletions(-)
>
> diff --git a/arch/x86/kernel/cpu/proc.c b/arch/x86/kernel/cpu/proc.c
> index 6df621ae62a7..c6c5217a7980 100644
> --- a/arch/x86/kernel/cpu/proc.c
> +++ b/arch/x86/kernel/cpu/proc.c
> @@ -30,8 +30,7 @@ static void show_cpuinfo_misc(struct seq_file *m, struct cpuinfo_x86 *c)
> "coma_bug\t: %s\n"
> "fpu\t\t: %s\n"
> "fpu_exception\t: %s\n"
> - "cpuid level\t: %d\n"
> - "wp\t\t: yes\n",
> + "cpuid level\t: %d\n",
> static_cpu_has_bug(X86_BUG_FDIV) ? "yes" : "no",
> static_cpu_has_bug(X86_BUG_F00F) ? "yes" : "no",
> static_cpu_has_bug(X86_BUG_COMA) ? "yes" : "no",
> @@ -45,8 +44,7 @@ static void show_cpuinfo_misc(struct seq_file *m, struct cpuinfo_x86 *c)
> seq_printf(m,
> "fpu\t\t: yes\n"
> "fpu_exception\t: yes\n"
> - "cpuid level\t: %d\n"
> - "wp\t\t: yes\n",
> + "cpuid level\t: %d\n",
> c->cpuid_level);
> }
> #endif
>
Potential userspace breakage, which is why the line was left in the
first place despite its value now being hard-coded. Removing it will
save a whopping 9 bytes of kernel rodata; this is a very small price to
pay for guaranteeing continued compatibility.
Nacked-by: H. Peter Anvin <hpa@zytor.com>
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| From | Borislav Petkov <bp@alien8.de> |
|---|---|
| Date | 2017-02-14 19:40 +0100 |
| Message-ID | <taQb8-5kY-17@gated-at.bofh.it> |
| In reply to | #1580731 |
On Tue, Feb 14, 2017 at 10:13:22AM -0800, H. Peter Anvin wrote:
> Potential userspace breakage, which is why the line was left in the
We could keep the string in /proc/cpuinfo for compatibility but kill the
cpuinfo_x86 members.
--
Regards/Gruss,
Boris.
Good mailing practices for 400: avoid top-posting and trim the reply.
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| From | Mathias Krause <minipli@googlemail.com> |
|---|---|
| Date | 2017-02-14 22:50 +0100 |
| Message-ID | <taT90-79j-5@gated-at.bofh.it> |
| In reply to | #1580731 |
On 14 February 2017 at 19:13, H. Peter Anvin <hpa@zytor.com> wrote:
> On 02/12/17 13:12, Mathias Krause wrote:
>> As of commit a5c2a893dbd4 ("x86, 386 removal: Remove
>> CONFIG_X86_WP_WORKS_OK") the kernel won't boot if CR0.WP isn't working
>> correctly. This makes a process reading this file always see "wp : yes"
>> here -- otherwise there would be no process to begin with ;)
>>
>> As this status line in /proc/cpuinfo serves no purpose for quite some
>> time now, get rid of it.
>>
>> Cc: Borislav Petkov <bp@alien8.de>
>> Cc: H. Peter Anvin <hpa@linux.intel.com>
>> Signed-off-by: Mathias Krause <minipli@googlemail.com>
>> ---
>> arch/x86/kernel/cpu/proc.c | 6 ++----
>> 1 file changed, 2 insertions(+), 4 deletions(-)
>>
>> diff --git a/arch/x86/kernel/cpu/proc.c b/arch/x86/kernel/cpu/proc.c
>> index 6df621ae62a7..c6c5217a7980 100644
>> --- a/arch/x86/kernel/cpu/proc.c
>> +++ b/arch/x86/kernel/cpu/proc.c
>> @@ -30,8 +30,7 @@ static void show_cpuinfo_misc(struct seq_file *m, struct cpuinfo_x86 *c)
>> "coma_bug\t: %s\n"
>> "fpu\t\t: %s\n"
>> "fpu_exception\t: %s\n"
>> - "cpuid level\t: %d\n"
>> - "wp\t\t: yes\n",
>> + "cpuid level\t: %d\n",
>> static_cpu_has_bug(X86_BUG_FDIV) ? "yes" : "no",
>> static_cpu_has_bug(X86_BUG_F00F) ? "yes" : "no",
>> static_cpu_has_bug(X86_BUG_COMA) ? "yes" : "no",
>> @@ -45,8 +44,7 @@ static void show_cpuinfo_misc(struct seq_file *m, struct cpuinfo_x86 *c)
>> seq_printf(m,
>> "fpu\t\t: yes\n"
>> "fpu_exception\t: yes\n"
>> - "cpuid level\t: %d\n"
>> - "wp\t\t: yes\n",
>> + "cpuid level\t: %d\n",
>> c->cpuid_level);
>> }
>> #endif
>>
>
> Potential userspace breakage, which is why the line was left in the
> first place despite its value now being hard-coded. Removing it will
> save a whopping 9 bytes of kernel rodata; this is a very small price to
> pay for guaranteeing continued compatibility.
Indeed. That's why I've separated the removal into an extra patch --
to make it easier not to take it.
>
> Nacked-by: H. Peter Anvin <hpa@zytor.com>
Do you want me to send the series again without this patch and patch
#6 (Geert took it already) or are you okay with sorting them out
yourself?
Cheers,
Mathias
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| From | Mathias Krause <minipli@googlemail.com> |
|---|---|
| Date | 2017-02-28 09:40 +0100 |
| Message-ID | <tfLu9-1T9-19@gated-at.bofh.it> |
| In reply to | #1580888 |
On 14 February 2017 at 22:42, Mathias Krause <minipli@googlemail.com> wrote:
> On 14 February 2017 at 19:13, H. Peter Anvin <hpa@zytor.com> wrote:
>> On 02/12/17 13:12, Mathias Krause wrote:
>>> As of commit a5c2a893dbd4 ("x86, 386 removal: Remove
>>> CONFIG_X86_WP_WORKS_OK") the kernel won't boot if CR0.WP isn't working
>>> correctly. This makes a process reading this file always see "wp : yes"
>>> here -- otherwise there would be no process to begin with ;)
>>>
>>> As this status line in /proc/cpuinfo serves no purpose for quite some
>>> time now, get rid of it.
>>>
>>> Cc: Borislav Petkov <bp@alien8.de>
>>> Cc: H. Peter Anvin <hpa@linux.intel.com>
>>> Signed-off-by: Mathias Krause <minipli@googlemail.com>
>>> ---
>>> arch/x86/kernel/cpu/proc.c | 6 ++----
>>> 1 file changed, 2 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/arch/x86/kernel/cpu/proc.c b/arch/x86/kernel/cpu/proc.c
>>> index 6df621ae62a7..c6c5217a7980 100644
>>> --- a/arch/x86/kernel/cpu/proc.c
>>> +++ b/arch/x86/kernel/cpu/proc.c
>>> @@ -30,8 +30,7 @@ static void show_cpuinfo_misc(struct seq_file *m, struct cpuinfo_x86 *c)
>>> "coma_bug\t: %s\n"
>>> "fpu\t\t: %s\n"
>>> "fpu_exception\t: %s\n"
>>> - "cpuid level\t: %d\n"
>>> - "wp\t\t: yes\n",
>>> + "cpuid level\t: %d\n",
>>> static_cpu_has_bug(X86_BUG_FDIV) ? "yes" : "no",
>>> static_cpu_has_bug(X86_BUG_F00F) ? "yes" : "no",
>>> static_cpu_has_bug(X86_BUG_COMA) ? "yes" : "no",
>>> @@ -45,8 +44,7 @@ static void show_cpuinfo_misc(struct seq_file *m, struct cpuinfo_x86 *c)
>>> seq_printf(m,
>>> "fpu\t\t: yes\n"
>>> "fpu_exception\t: yes\n"
>>> - "cpuid level\t: %d\n"
>>> - "wp\t\t: yes\n",
>>> + "cpuid level\t: %d\n",
>>> c->cpuid_level);
>>> }
>>> #endif
>>>
>>
>> Potential userspace breakage, which is why the line was left in the
>> first place despite its value now being hard-coded. Removing it will
>> save a whopping 9 bytes of kernel rodata; this is a very small price to
>> pay for guaranteeing continued compatibility.
>
> Indeed. That's why I've separated the removal into an extra patch --
> to make it easier not to take it.
>
>>
>> Nacked-by: H. Peter Anvin <hpa@zytor.com>
>
> Do you want me to send the series again without this patch and patch
> #6 (Geert took it already) or are you okay with sorting them out
> yourself?
>
Ping...
Peter, what's your preference here?
Mathias
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