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Date: Tue, 10 Apr 2012 20:20:53 -0700
From: "H. Peter Anvin" <hpa@...or.com>
To: Will Drewry <wad@...omium.org>
CC: linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org,
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Subject: Re: [PATCH v15 04/13] arch/x86: add syscall_get_arch to syscall.h
On 04/10/2012 08:13 PM, Will Drewry wrote:
> On Sun, Mar 25, 2012 at 2:34 PM, H. Peter Anvin <hpa@...or.com> wrote:
>> On 03/14/2012 08:11 PM, Will Drewry wrote:
>>>
>>> +static inline int syscall_get_arch(struct task_struct *task,
>>> + struct pt_regs *regs)
>>> +{
>>> +#ifdef CONFIG_IA32_EMULATION
>>> + /*
>>> + * TS_COMPAT is set for 32-bit syscall entries and then
>>> + * remains set until we return to user mode.
>>> + *
>>> + * TIF_IA32 tasks should always have TS_COMPAT set at
>>> + * system call time.
>>> + */
>>> + if (task_thread_info(task)->status & TS_COMPAT)
>>> + return AUDIT_ARCH_I386;
>>> +#endif
>>> + return AUDIT_ARCH_X86_64;
>>> +}
>>> #endif /* CONFIG_X86_32 */
>>>
>>> #endif /* _ASM_X86_SYSCALL_H */
>>
>> Just one FYI on this: after the x32 changes are upstream this can be
>> implemented in terms of is_ia32_task().
>
> Now that I've seen is_ia32_task(), it appears to be exactly the same as above:
> (1) If we're x86_32, it's ia32
> (2) If we're x86_64, ia32 == !!(status & TS_COMPAT)
> (3) Otherwise, it's x86_64, including x32
>
> Am I missing something? Should is_ia32_task(void) take a task_struct?
> Right now, I don't see any reason to change the code, as posted, but
> maybe I am mis-reading?
>
Sorry, answered the wrong question. Yes, it is the same as above...
just wandered if we could centralize this test. It might indeed make
sense to provide general predicates which take a task pointer.
-hpa
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