Hey Jisheng, On Thu, Jan 12, 2023 at 01:10:24AM +0800, Jisheng Zhang wrote: > Make it possible to use alternatives in the vDSO, so that better > implementations can be used if possible. > > Signed-off-by: Jisheng Zhang <jszhang@xxxxxxxxxx> > Reviewed-by: Guo Ren <guoren@xxxxxxxxxx> > Reviewed-by: Andrew Jones <ajones@xxxxxxxxxxxxxxxx> FYI, from this patch onwards the rv32 build is broken. Should be reproduceable with the in-tree rv32_defconfig. Unfortunately no logs for you, I've got a CI bug to fix! Thanks, Conor. > --- > arch/riscv/include/asm/vdso.h | 4 ++++ > arch/riscv/kernel/alternative.c | 25 +++++++++++++++++++++++++ > arch/riscv/kernel/vdso.c | 5 ----- > arch/riscv/kernel/vdso/vdso.lds.S | 7 +++++++ > 4 files changed, 36 insertions(+), 5 deletions(-) > > diff --git a/arch/riscv/include/asm/vdso.h b/arch/riscv/include/asm/vdso.h > index a7644f46d0e5..f891478829a5 100644 > --- a/arch/riscv/include/asm/vdso.h > +++ b/arch/riscv/include/asm/vdso.h > @@ -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 */ > diff --git a/arch/riscv/kernel/alternative.c b/arch/riscv/kernel/alternative.c > index 3d4f1f32c7f6..a883a309139f 100644 > --- a/arch/riscv/kernel/alternative.c > +++ b/arch/riscv/kernel/alternative.c > @@ -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 +162,27 @@ static void __init_or_module _apply_alternatives(struct alt_entry *begin, > stage); > } > > +static void __init apply_vdso_alternatives(void) > +{ > + const struct elf64_hdr *hdr; > + const struct elf64_shdr *shdr; > + const struct elf64_shdr *alt; > + struct alt_entry *begin, *end; > + > + hdr = (struct elf64_hdr *)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); > +} > + > void __init apply_boot_alternatives(void) > { > /* If called on non-boot cpu things could go wrong */ > @@ -168,6 +191,8 @@ void __init apply_boot_alternatives(void) > _apply_alternatives((struct alt_entry *)__alt_start, > (struct alt_entry *)__alt_end, > RISCV_ALTERNATIVES_BOOT); > + > + apply_vdso_alternatives(); > } > > /* > diff --git a/arch/riscv/kernel/vdso.c b/arch/riscv/kernel/vdso.c > index e410275918ac..4e631c098f4d 100644 > --- a/arch/riscv/kernel/vdso.c > +++ b/arch/riscv/kernel/vdso.c > @@ -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, > diff --git a/arch/riscv/kernel/vdso/vdso.lds.S b/arch/riscv/kernel/vdso/vdso.lds.S > index 150b1a572e61..4a0606633290 100644 > --- a/arch/riscv/kernel/vdso/vdso.lds.S > +++ b/arch/riscv/kernel/vdso/vdso.lds.S > @@ -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.*) > -- > 2.38.1 >
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