linux-kernel - Re: [PATCH AUTOSEL 4.19 1/4] x86/mm: Move is_vsyscall

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Date: Mon, 11 Mar 2024 22:12:02 +0100
From: Pavel Machek <pavel@....cz>
To: Sasha Levin <sashal@...nel.org>
Cc: linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	Hou Tao <houtao1@...wei.com>, Sohil Mehta <sohil.mehta@...el.com>,
	Alexei Starovoitov <ast@...nel.org>, tglx@...utronix.de,
	mingo@...hat.com, bp@...en8.de, dave.hansen@...ux.intel.com,
	x86@...nel.org
Subject: Re: [PATCH AUTOSEL 4.19 1/4] x86/mm: Move is_vsyscall_vaddr() into
 asm/vsyscall.h

Hi!

> Move is_vsyscall_vaddr() into asm/vsyscall.h to make it available for
> copy_from_kernel_nofault_allowed() in arch/x86/mm/maccess.c.

This seems to be just part of a patch -- it does not move anything --
and we should not really need it for 4.19, as we don't have those
copy_from_kernel_nofault_allowed changes.

Best regards,
								Pavel
								

> +++ b/arch/x86/include/asm/vsyscall.h
> @@ -4,6 +4,7 @@
>  
>  #include <linux/seqlock.h>
>  #include <uapi/asm/vsyscall.h>
> +#include <asm/page_types.h>
>  
>  #ifdef CONFIG_X86_VSYSCALL_EMULATION
>  extern void map_vsyscall(void);
> @@ -22,4 +23,13 @@ static inline bool emulate_vsyscall(struct pt_regs *regs, unsigned long address)
>  }
>  #endif
>  
> +/*
> + * The (legacy) vsyscall page is the long page in the kernel portion
> + * of the address space that has user-accessible permissions.
> + */
> +static inline bool is_vsyscall_vaddr(unsigned long vaddr)
> +{
> +	return unlikely((vaddr & PAGE_MASK) == VSYSCALL_ADDR);
> +}
> +
>  #endif /* _ASM_X86_VSYSCALL_H */

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