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SubjectRe: [PATCH v2 3/4] x86: Patch alternatives in the 32-bit vDSO
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Am Donnerstag, den 27.02.2014, 16:18 -0800 schrieb Andy Lutomirski:
> rdtsc_barrier() needs this.
>
> Signed-off-by: Andy Lutomirski <luto@amacapital.net>
> ---
> arch/x86/include/asm/vdso.h | 2 ++
> arch/x86/vdso/vdso32-setup.c | 25 +++++++++++++------------
> arch/x86/vdso/vma.c | 9 ++++++---
> 3 files changed, 21 insertions(+), 15 deletions(-)
>
> diff --git a/arch/x86/include/asm/vdso.h b/arch/x86/include/asm/vdso.h
> index 6db8b23..a844f90 100644
> --- a/arch/x86/include/asm/vdso.h
> +++ b/arch/x86/include/asm/vdso.h
> @@ -40,4 +40,6 @@ extern const char vdso32_int80_start, vdso32_int80_end;
> extern const char vdso32_syscall_start, vdso32_syscall_end;
> extern const char vdso32_sysenter_start, vdso32_sysenter_end;
>
> +void __init patch_vdso32(void *vdso, size_t len);
> +
> #endif /* _ASM_X86_VDSO_H */
> diff --git a/arch/x86/vdso/vdso32-setup.c b/arch/x86/vdso/vdso32-setup.c
> index 6b74a46..b37aa1d 100644
> --- a/arch/x86/vdso/vdso32-setup.c
> +++ b/arch/x86/vdso/vdso32-setup.c
> @@ -273,29 +273,30 @@ static void map_compat_vdso(int map)
>
> int __init sysenter_setup(void)
> {
> - void *syscall_page = (void *)get_zeroed_page(GFP_ATOMIC);
> - const void *vsyscall;
> - size_t vsyscall_len;
> + void *vdso_page = (void *)get_zeroed_page(GFP_ATOMIC);
> + const void *vdso;
> + size_t vdso_len;
>
> - vdso32_pages[0] = virt_to_page(syscall_page);
> + vdso32_pages[0] = virt_to_page(vdso_page);
>
> #ifdef CONFIG_X86_32
> gate_vma_init();
> #endif
>
> if (vdso32_syscall()) {
> - vsyscall = &vdso32_syscall_start;
> - vsyscall_len = &vdso32_syscall_end - &vdso32_syscall_start;
> + vdso = &vdso32_syscall_start;
> + vdso_len = &vdso32_syscall_end - &vdso32_syscall_start;
> } else if (vdso32_sysenter()){
> - vsyscall = &vdso32_sysenter_start;
> - vsyscall_len = &vdso32_sysenter_end - &vdso32_sysenter_start;
> + vdso = &vdso32_sysenter_start;
> + vdso_len = &vdso32_sysenter_end - &vdso32_sysenter_start;
> } else {
> - vsyscall = &vdso32_int80_start;
> - vsyscall_len = &vdso32_int80_end - &vdso32_int80_start;
> + vdso = &vdso32_int80_start;
> + vdso_len = &vdso32_int80_end - &vdso32_int80_start;
> }
>
> - memcpy(syscall_page, vsyscall, vsyscall_len);
> - relocate_vdso(syscall_page);
> + memcpy(vdso_page, vdso, vdso_len);
> + patch_vdso32(vdso_page, vdso_len);

This will fail with 32 bit kernels since vma.c is only build for 64 bit
kernel. I have fixed this.

> + relocate_vdso(vdso_page);
>
> return 0;
> }
> diff --git a/arch/x86/vdso/vma.c b/arch/x86/vdso/vma.c
> index 431e875..149caa1 100644
> --- a/arch/x86/vdso/vma.c
> +++ b/arch/x86/vdso/vma.c
> @@ -28,8 +28,11 @@ static unsigned vdso_size;
> extern char vdsox32_start[], vdsox32_end[];
> extern struct page *vdsox32_pages[];
> static unsigned vdsox32_size;
> +#endif
>
> -static void __init patch_vdsox32(void *vdso, size_t len)
> +#if defined(CONFIG_X86_32) || defined(CONFIG_X86_X32_ABI) || \
> + defined(CONFIG_COMPAT)
> +void __init patch_vdso32(void *vdso, size_t len)
> {
> Elf32_Ehdr *hdr = vdso;
> Elf32_Shdr *sechdrs, *alt_sec = 0;
> @@ -52,7 +55,7 @@ static void __init patch_vdsox32(void *vdso, size_t len)
> }
>
> /* If we get here, it's probably a bug. */
> - pr_warning("patch_vdsox32: .altinstructions not found\n");
> + pr_warning("patch_vdso32: .altinstructions not found\n");
> return; /* nothing to patch */
>
> found:
> @@ -104,7 +107,7 @@ static int __init init_vdso(void)
> vdso_pages[i] = virt_to_page(vdso_start + i*PAGE_SIZE);
>
> #ifdef CONFIG_X86_X32_ABI
> - patch_vdsox32(vdsox32_start, vdsox32_end - vdsox32_start);
> + patch_vdso32(vdsox32_start, vdsox32_end - vdsox32_start);
> npages = (vdsox32_end - vdsox32_start + PAGE_SIZE - 1) / PAGE_SIZE;
> vdsox32_size = npages << PAGE_SHIFT;
> for (i = 0; i < npages; i++)




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