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[PATCH v2 10/13] riscv: alternative: patch alternatives in the vDSO

Jisheng Zhang posted 13 patches 3 years, 2 months ago
There is a newer version of this series
[PATCH v2 10/13] riscv: alternative: patch alternatives in the vDSO
Posted by Jisheng Zhang 3 years, 2 months ago 
Make it possible to use alternatives in the vDSO, so that better
implementations can be used if possible.

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
---
 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 af981426fe0f..b6ff7473fb8a 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 9d88375624b5..eaf7ddaba54c 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>
@@ -187,6 +189,27 @@ 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 */
@@ -195,6 +218,8 @@ 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 123d05255fcf..1f47bc6566cf 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.*)
-- 
2.37.2
Re: [PATCH v2 10/13] riscv: alternative: patch alternatives in the vDSO
Posted by Andrew Jones 3 years ago 
On Mon, Dec 05, 2022 at 01:46:29AM +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@kernel.org>
> ---
>  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(-)
>

Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Re: [PATCH v2 10/13] riscv: alternative: patch alternatives in the vDSO
Posted by Guo Ren 3 years, 2 months ago 
Are there any patches that depend on it? Any existing utilization? My
first idea is to let __vdso_flush_icache use it, the standard
implementation is so heavy for user space JIT scenario, maybe vendors
could give a custom one.

On Mon, Dec 5, 2022 at 1:57 AM Jisheng Zhang <jszhang@kernel.org> 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@kernel.org>
> ---
>  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 af981426fe0f..b6ff7473fb8a 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 9d88375624b5..eaf7ddaba54c 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>
> @@ -187,6 +189,27 @@ 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 */
> @@ -195,6 +218,8 @@ 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 123d05255fcf..1f47bc6566cf 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.*)
> --
> 2.37.2
>


-- 
Best Regards
 Guo Ren
Re: [PATCH v2 10/13] riscv: alternative: patch alternatives in the vDSO
Posted by Jisheng Zhang 3 years, 2 months ago 
On Mon, Dec 05, 2022 at 09:56:37AM +0800, Guo Ren wrote:
> Are there any patches that depend on it? Any existing utilization? My
> first idea is to let __vdso_flush_icache use it, the standard
> implementation is so heavy for user space JIT scenario, maybe vendors
> could give a custom one.

Hi Guo,

the 11th patch of swtiching cpu_relax() to riscv_has_extension_likely()
depends on this patch, the gettimeofday implementation calls cpu_relax()
which may use ZIHINTPAUSE extension, so we need to patch vDSO.

Thanks

> 
> On Mon, Dec 5, 2022 at 1:57 AM Jisheng Zhang <jszhang@kernel.org> 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@kernel.org>
> > ---
> >  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 af981426fe0f..b6ff7473fb8a 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 9d88375624b5..eaf7ddaba54c 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>
> > @@ -187,6 +189,27 @@ 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 */
> > @@ -195,6 +218,8 @@ 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 123d05255fcf..1f47bc6566cf 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.*)
> > --
> > 2.37.2
> >
> 
> 
> -- 
> Best Regards
>  Guo Ren
Re: [PATCH v2 10/13] riscv: alternative: patch alternatives in the vDSO
Posted by Guo Ren 3 years, 2 months ago 
On Mon, Dec 5, 2022 at 11:33 PM Jisheng Zhang <jszhang@kernel.org> wrote:
>
> On Mon, Dec 05, 2022 at 09:56:37AM +0800, Guo Ren wrote:
> > Are there any patches that depend on it? Any existing utilization? My
> > first idea is to let __vdso_flush_icache use it, the standard
> > implementation is so heavy for user space JIT scenario, maybe vendors
> > could give a custom one.
>
> Hi Guo,
>
> the 11th patch of swtiching cpu_relax() to riscv_has_extension_likely()
> depends on this patch, the gettimeofday implementation calls cpu_relax()
> which may use ZIHINTPAUSE extension, so we need to patch vDSO.
Oh, I missed that. Thx.

Reviewed-by: Guo Ren <guoren@kernel.org>

>
> Thanks
>
> >
> > On Mon, Dec 5, 2022 at 1:57 AM Jisheng Zhang <jszhang@kernel.org> 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@kernel.org>
> > > ---
> > >  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 af981426fe0f..b6ff7473fb8a 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 9d88375624b5..eaf7ddaba54c 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>
> > > @@ -187,6 +189,27 @@ 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 */
> > > @@ -195,6 +218,8 @@ 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 123d05255fcf..1f47bc6566cf 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.*)
> > > --
> > > 2.37.2
> > >
> >
> >
> > --
> > Best Regards
> >  Guo Ren



-- 
Best Regards
 Guo Ren

Patchew 2.1-devel-b67e4c2

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