[PATCH v23 08/13] x86, vdso: Patch alternatives in the 32-bit VDSO

From: Stefani Seibold
Date: Mon Mar 17 2014 - 18:24:32 EST


From: Andy Lutomirski <luto@xxxxxxxxxxxxxx>

We need the alternatives mechanism for rdtsc_barrier() to work.

Signed-off-by: Stefani Seibold <stefani@xxxxxxxxxxx>
---
arch/x86/include/asm/vdso.h | 2 ++
arch/x86/vdso/Makefile | 3 ++-
arch/x86/vdso/vdso32-setup.c | 23 ++++++++++++-----------
arch/x86/vdso/vma.c | 13 ++++++++++---
4 files changed, 26 insertions(+), 15 deletions(-)

diff --git a/arch/x86/include/asm/vdso.h b/arch/x86/include/asm/vdso.h
index 5594e84..f8605e6 100644
--- a/arch/x86/include/asm/vdso.h
+++ b/arch/x86/include/asm/vdso.h
@@ -28,4 +28,6 @@ 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/Makefile b/arch/x86/vdso/Makefile
index fd14be1..7a3d13e 100644
--- a/arch/x86/vdso/Makefile
+++ b/arch/x86/vdso/Makefile
@@ -21,7 +21,8 @@ vobjs-$(VDSOX32-y) += $(vobjx32s-compat)
vobj64s := $(filter-out $(vobjx32s-compat),$(vobjs-y))

# files to link into kernel
-obj-$(VDSO64-y) += vma.o vdso.o
+obj-y += vma.o
+obj-$(VDSO64-y) += vdso.o
obj-$(VDSOX32-y) += vdsox32.o
obj-$(VDSO32-y) += vdso32.o vdso32-setup.o

diff --git a/arch/x86/vdso/vdso32-setup.c b/arch/x86/vdso/vdso32-setup.c
index ab20c04..e0fc767 100644
--- a/arch/x86/vdso/vdso32-setup.c
+++ b/arch/x86/vdso/vdso32-setup.c
@@ -112,24 +112,25 @@ void enable_sep_cpu(void)

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);

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);
+ memcpy(vdso_page, vdso, vdso_len);
+ patch_vdso32(vdso_page, vdso_len);

return 0;
}
diff --git a/arch/x86/vdso/vma.c b/arch/x86/vdso/vma.c
index 431e875..7345bc9 100644
--- a/arch/x86/vdso/vma.c
+++ b/arch/x86/vdso/vma.c
@@ -16,6 +16,7 @@
#include <asm/vdso.h>
#include <asm/page.h>

+#if defined(CONFIG_X86_64)
unsigned int __read_mostly vdso_enabled = 1;

extern char vdso_start[], vdso_end[];
@@ -28,8 +29,12 @@ static unsigned vdso_size;
extern char vdsox32_start[], vdsox32_end[];
extern struct page *vdsox32_pages[];
static unsigned vdsox32_size;
+#endif
+#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 +57,7 @@ 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:
@@ -61,6 +66,7 @@ found:
}
#endif

+#if defined(CONFIG_X86_64)
static void __init patch_vdso64(void *vdso, size_t len)
{
Elf64_Ehdr *hdr = vdso;
@@ -104,7 +110,7 @@ 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++)
@@ -204,3 +210,4 @@ static __init int vdso_setup(char *s)
return 0;
}
__setup("vdso=", vdso_setup);
+#endif
--
1.9.0

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