| Message ID | 20220830104833.34636-3-joey.gouly@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Use CNTVCTSS_EL0 in gettimeofday() | expand |
On Tue, Aug 30, 2022 at 11:48:32AM +0100, Joey Gouly wrote: > Make it possible to use alternatives in the vDSO, so that better > implementations can be used if possible. > > Signed-off-by: Joey Gouly <joey.gouly@arm.com> > Cc: Catalin Marinas <catalin.marinas@arm.com> > Cc: Will Deacon <will@kernel.org> > Cc: Vincenzo Frascino <vincenzo.frascino@arm.com> > Cc: Mark Rutland <mark.rutland@arm.com> Acked-by: Mark Rutland <mark.rutland@arm.com> Mark. > --- > arch/arm64/include/asm/vdso.h | 3 +++ > arch/arm64/kernel/alternative.c | 28 ++++++++++++++++++++++++++++ > arch/arm64/kernel/vdso.c | 3 --- > arch/arm64/kernel/vdso/vdso.lds.S | 7 +++++++ > 4 files changed, 38 insertions(+), 3 deletions(-) > > diff --git a/arch/arm64/include/asm/vdso.h b/arch/arm64/include/asm/vdso.h > index f99dcb94b438..b4ae32109932 100644 > --- a/arch/arm64/include/asm/vdso.h > +++ b/arch/arm64/include/asm/vdso.h > @@ -26,6 +26,9 @@ > (void *)(vdso_offset_##name - VDSO_LBASE + (unsigned long)(base)); \ > }) > > +extern char vdso_start[], vdso_end[]; > +extern char vdso32_start[], vdso32_end[]; > + > #endif /* !__ASSEMBLY__ */ > > #endif /* __ASM_VDSO_H */ > diff --git a/arch/arm64/kernel/alternative.c b/arch/arm64/kernel/alternative.c > index 9bcaa5eacf16..a97775963f35 100644 > --- a/arch/arm64/kernel/alternative.c > +++ b/arch/arm64/kernel/alternative.c > @@ -10,11 +10,14 @@ > > #include <linux/init.h> > #include <linux/cpu.h> > +#include <linux/elf.h> > #include <asm/cacheflush.h> > #include <asm/alternative.h> > #include <asm/cpufeature.h> > #include <asm/insn.h> > +#include <asm/module.h> > #include <asm/sections.h> > +#include <asm/vdso.h> > #include <linux/stop_machine.h> > > #define __ALT_PTR(a, f) ((void *)&(a)->f + (a)->f) > @@ -192,6 +195,30 @@ static void __nocfi __apply_alternatives(struct alt_region *region, bool is_modu > } > } > > +void apply_alternatives_vdso(void) > +{ > + struct alt_region region; > + const struct elf64_hdr *hdr; > + const struct elf64_shdr *shdr; > + const struct elf64_shdr *alt; > + DECLARE_BITMAP(all_capabilities, ARM64_NPATCHABLE); > + > + bitmap_fill(all_capabilities, ARM64_NPATCHABLE); > + > + hdr = (struct elf64_hdr *)vdso_start; > + shdr = (void *)hdr + hdr->e_shoff; > + alt = find_section(hdr, shdr, ".altinstructions"); > + if (!alt) > + return; > + > + region = (struct alt_region){ > + .begin = (void *)hdr + alt->sh_offset, > + .end = (void *)hdr + alt->sh_offset + alt->sh_size, > + }; > + > + __apply_alternatives(®ion, false, &all_capabilities[0]); > +} > + > /* > * We might be patching the stop_machine state machine, so implement a > * really simple polling protocol here. > @@ -225,6 +252,7 @@ static int __apply_alternatives_multi_stop(void *unused) > > void __init apply_alternatives_all(void) > { > + apply_alternatives_vdso(); > /* better not try code patching on a live SMP system */ > stop_machine(__apply_alternatives_multi_stop, NULL, cpu_online_mask); > } > diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c > index a61fc4f989b3..ac93a2ee9c07 100644 > --- a/arch/arm64/kernel/vdso.c > +++ b/arch/arm64/kernel/vdso.c > @@ -29,9 +29,6 @@ > #include <asm/signal32.h> > #include <asm/vdso.h> > > -extern char vdso_start[], vdso_end[]; > -extern char vdso32_start[], vdso32_end[]; > - > enum vdso_abi { > VDSO_ABI_AA64, > VDSO_ABI_AA32, > diff --git a/arch/arm64/kernel/vdso/vdso.lds.S b/arch/arm64/kernel/vdso/vdso.lds.S > index e69fb4aaaf3e..6028f1fe2d1c 100644 > --- a/arch/arm64/kernel/vdso/vdso.lds.S > +++ b/arch/arm64/kernel/vdso/vdso.lds.S > @@ -48,6 +48,13 @@ SECTIONS > PROVIDE (_etext = .); > PROVIDE (etext = .); > > + . = ALIGN(4); > + .altinstructions : { > + __alt_instructions = .; > + *(.altinstructions) > + __alt_instructions_end = .; > + } > + > .dynamic : { *(.dynamic) } :text :dynamic > > .rela.dyn : ALIGN(8) { *(.rela .rela*) } > -- > 2.17.1 >
diff --git a/arch/arm64/include/asm/vdso.h b/arch/arm64/include/asm/vdso.h index f99dcb94b438..b4ae32109932 100644 --- a/arch/arm64/include/asm/vdso.h +++ b/arch/arm64/include/asm/vdso.h @@ -26,6 +26,9 @@ (void *)(vdso_offset_##name - VDSO_LBASE + (unsigned long)(base)); \ }) +extern char vdso_start[], vdso_end[]; +extern char vdso32_start[], vdso32_end[]; + #endif /* !__ASSEMBLY__ */ #endif /* __ASM_VDSO_H */ diff --git a/arch/arm64/kernel/alternative.c b/arch/arm64/kernel/alternative.c index 9bcaa5eacf16..a97775963f35 100644 --- a/arch/arm64/kernel/alternative.c +++ b/arch/arm64/kernel/alternative.c @@ -10,11 +10,14 @@ #include <linux/init.h> #include <linux/cpu.h> +#include <linux/elf.h> #include <asm/cacheflush.h> #include <asm/alternative.h> #include <asm/cpufeature.h> #include <asm/insn.h> +#include <asm/module.h> #include <asm/sections.h> +#include <asm/vdso.h> #include <linux/stop_machine.h> #define __ALT_PTR(a, f) ((void *)&(a)->f + (a)->f) @@ -192,6 +195,30 @@ static void __nocfi __apply_alternatives(struct alt_region *region, bool is_modu } } +void apply_alternatives_vdso(void) +{ + struct alt_region region; + const struct elf64_hdr *hdr; + const struct elf64_shdr *shdr; + const struct elf64_shdr *alt; + DECLARE_BITMAP(all_capabilities, ARM64_NPATCHABLE); + + bitmap_fill(all_capabilities, ARM64_NPATCHABLE); + + hdr = (struct elf64_hdr *)vdso_start; + shdr = (void *)hdr + hdr->e_shoff; + alt = find_section(hdr, shdr, ".altinstructions"); + if (!alt) + return; + + region = (struct alt_region){ + .begin = (void *)hdr + alt->sh_offset, + .end = (void *)hdr + alt->sh_offset + alt->sh_size, + }; + + __apply_alternatives(®ion, false, &all_capabilities[0]); +} + /* * We might be patching the stop_machine state machine, so implement a * really simple polling protocol here. @@ -225,6 +252,7 @@ static int __apply_alternatives_multi_stop(void *unused) void __init apply_alternatives_all(void) { + apply_alternatives_vdso(); /* better not try code patching on a live SMP system */ stop_machine(__apply_alternatives_multi_stop, NULL, cpu_online_mask); } diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c index a61fc4f989b3..ac93a2ee9c07 100644 --- a/arch/arm64/kernel/vdso.c +++ b/arch/arm64/kernel/vdso.c @@ -29,9 +29,6 @@ #include <asm/signal32.h> #include <asm/vdso.h> -extern char vdso_start[], vdso_end[]; -extern char vdso32_start[], vdso32_end[]; - enum vdso_abi { VDSO_ABI_AA64, VDSO_ABI_AA32, diff --git a/arch/arm64/kernel/vdso/vdso.lds.S b/arch/arm64/kernel/vdso/vdso.lds.S index e69fb4aaaf3e..6028f1fe2d1c 100644 --- a/arch/arm64/kernel/vdso/vdso.lds.S +++ b/arch/arm64/kernel/vdso/vdso.lds.S @@ -48,6 +48,13 @@ SECTIONS PROVIDE (_etext = .); PROVIDE (etext = .); + . = ALIGN(4); + .altinstructions : { + __alt_instructions = .; + *(.altinstructions) + __alt_instructions_end = .; + } + .dynamic : { *(.dynamic) } :text :dynamic .rela.dyn : ALIGN(8) { *(.rela .rela*) }
Make it possible to use alternatives in the vDSO, so that better implementations can be used if possible. Signed-off-by: Joey Gouly <joey.gouly@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will@kernel.org> Cc: Vincenzo Frascino <vincenzo.frascino@arm.com> Cc: Mark Rutland <mark.rutland@arm.com> --- arch/arm64/include/asm/vdso.h | 3 +++ arch/arm64/kernel/alternative.c | 28 ++++++++++++++++++++++++++++ arch/arm64/kernel/vdso.c | 3 --- arch/arm64/kernel/vdso/vdso.lds.S | 7 +++++++ 4 files changed, 38 insertions(+), 3 deletions(-)