Unverified Commit cabfd146 authored by Jisheng Zhang's avatar Jisheng Zhang Committed by Palmer Dabbelt
Browse files

riscv: alternative: patch alternatives in the vDSO 



Make it possible to use alternatives in the vDSO, so that better
implementations can be used if possible.

Signed-off-by: default avatarJisheng Zhang <jszhang@kernel.org>
Reviewed-by: default avatarGuo Ren <guoren@kernel.org>
Reviewed-by: default avatarAndrew Jones <ajones@ventanamicro.com>
Link: https://lore.kernel.org/r/20230128172856.3814-11-jszhang@kernel.org


Signed-off-by: default avatarPalmer Dabbelt <palmer@rivosinc.com>
parent 8d23e94a

arch/riscv/include/asm/vdso.h

+4 −0
Original line number Diff line number Diff line
@@ -28,8 +28,12 @@ 
#define COMPAT_VDSO_SYMBOL(base, name)						\

	(void __user *)((unsigned long)(base) + compat__vdso_##name##_offset)



extern char compat_vdso_start[], compat_vdso_end[];



#endif /* CONFIG_COMPAT */



extern char vdso_start[], vdso_end[];



#endif /* !__ASSEMBLY__ */



#endif /* CONFIG_MMU */

arch/riscv/kernel/alternative.c

+29 −0
Original line number Diff line number Diff line
@@ -11,7 +11,9 @@ 
#include <linux/cpu.h>

#include <linux/uaccess.h>

#include <asm/alternative.h>

#include <asm/module.h>

#include <asm/sections.h>

#include <asm/vdso.h>

#include <asm/vendorid_list.h>

#include <asm/sbi.h>

#include <asm/csr.h>
@@ -160,6 +162,31 @@ static void __init_or_module _apply_alternatives(struct alt_entry *begin, 
				stage);

}



#ifdef CONFIG_MMU

static void __init apply_vdso_alternatives(void)

{

	const Elf_Ehdr *hdr;

	const Elf_Shdr *shdr;

	const Elf_Shdr *alt;

	struct alt_entry *begin, *end;



	hdr = (Elf_Ehdr *)vdso_start;

	shdr = (void *)hdr + hdr->e_shoff;

	alt = find_section(hdr, shdr, ".alternative");

	if (!alt)

		return;



	begin = (void *)hdr + alt->sh_offset,

	end = (void *)hdr + alt->sh_offset + alt->sh_size,



	_apply_alternatives((struct alt_entry *)begin,

			    (struct alt_entry *)end,

			    RISCV_ALTERNATIVES_BOOT);

}

#else

static void __init apply_vdso_alternatives(void) { }

#endif



void __init apply_boot_alternatives(void)

{

	/* If called on non-boot cpu things could go wrong */
@@ -168,6 +195,8 @@ void __init apply_boot_alternatives(void) 
	_apply_alternatives((struct alt_entry *)__alt_start,

			    (struct alt_entry *)__alt_end,

			    RISCV_ALTERNATIVES_BOOT);



	apply_vdso_alternatives();

}



/*

arch/riscv/kernel/vdso.c

+0 −5
Original line number Diff line number Diff line
@@ -22,11 +22,6 @@ struct vdso_data { 
};

#endif



extern char vdso_start[], vdso_end[];

#ifdef CONFIG_COMPAT

extern char compat_vdso_start[], compat_vdso_end[];

#endif



enum vvar_pages {

	VVAR_DATA_PAGE_OFFSET,

	VVAR_TIMENS_PAGE_OFFSET,

arch/riscv/kernel/vdso/vdso.lds.S

+7 −0
Original line number Diff line number Diff line
@@ -40,6 +40,13 @@ SECTIONS 
	. = 0x800;

	.text		: { *(.text .text.*) }		:text



	. = ALIGN(4);

	.alternative : {

		__alt_start = .;

		*(.alternative)

		__alt_end = .;

	}



	.data		: {

		*(.got.plt) *(.got)

		*(.data .data.* .gnu.linkonce.d.*)