[PATCH] x86: Load the 32-bit vdso in place, just like the 64-bit vdsos
From: Andy Lutomirski
Date: Thu Mar 20 2014 - 18:01:40 EST
This replaces a decent amount of incomprehensible and buggy code
with much more straightforward code. It also brings the 32-bit vdso
more in line with the 64-bit vdsos, so maybe someday they can share
even more code.
This wastes a small amount of kernel .data and .text space, but it
avoids a couple of allocations on startup, so it should be more or
less a wash memory-wise.
Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
---
arch/x86/include/asm/vdso.h | 8 -------
arch/x86/vdso/vdso.S | 22 ++-----------------
arch/x86/vdso/vdso32-setup.c | 50 +++++++++++++++++++++++++-------------------
arch/x86/vdso/vdso32.S | 21 ++++---------------
arch/x86/vdso/vdso_image.h | 30 ++++++++++++++++++++++++++
arch/x86/vdso/vdsox32.S | 22 ++-----------------
arch/x86/vdso/vma.c | 8 +++----
7 files changed, 70 insertions(+), 91 deletions(-)
create mode 100644 arch/x86/vdso/vdso_image.h
diff --git a/arch/x86/include/asm/vdso.h b/arch/x86/include/asm/vdso.h
index bde4359..0301d78 100644
--- a/arch/x86/include/asm/vdso.h
+++ b/arch/x86/include/asm/vdso.h
@@ -25,14 +25,6 @@ extern const char VDSO32_PRELINK[];
extern void __user __kernel_sigreturn;
extern void __user __kernel_rt_sigreturn;
-/*
- * These symbols are defined by vdso32.S to mark the bounds
- * of the ELF DSO images included therein.
- */
-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/vdso.S b/arch/x86/vdso/vdso.S
index 1e13eb8..c749d15 100644
--- a/arch/x86/vdso/vdso.S
+++ b/arch/x86/vdso/vdso.S
@@ -1,21 +1,3 @@
-#include <asm/page_types.h>
-#include <linux/linkage.h>
+#include "vdso_image.h"
-__PAGE_ALIGNED_DATA
-
- .globl vdso_start, vdso_end
- .align PAGE_SIZE
-vdso_start:
- .incbin "arch/x86/vdso/vdso.so"
-vdso_end:
- .align PAGE_SIZE /* extra data here leaks to userspace. */
-
-.previous
-
- .globl vdso_pages
- .bss
- .align 8
- .type vdso_pages, @object
-vdso_pages:
- .zero (vdso_end - vdso_start + PAGE_SIZE - 1) / PAGE_SIZE * 8
- .size vdso_pages, .-vdso_pages
+DEFINE_VDSO_IMAGE(vdso, "arch/x86/vdso/vdso.so")
diff --git a/arch/x86/vdso/vdso32-setup.c b/arch/x86/vdso/vdso32-setup.c
index 5b4aaef..b45528e 100644
--- a/arch/x86/vdso/vdso32-setup.c
+++ b/arch/x86/vdso/vdso32-setup.c
@@ -29,6 +29,7 @@
#include <asm/fixmap.h>
#include <asm/hpet.h>
#include <asm/vvar.h>
+#include "vdso_image.h"
#ifdef CONFIG_COMPAT_VDSO
#define VDSO_DEFAULT 0
@@ -41,6 +42,12 @@
#define arch_setup_additional_pages syscall32_setup_pages
#endif
+DECLARE_VDSO_IMAGE(vdso32_int80);
+#ifdef CONFIG_COMPAT
+DECLARE_VDSO_IMAGE(vdso32_syscall);
+#endif
+DECLARE_VDSO_IMAGE(vdso32_sysenter);
+
/*
* Should the kernel map a VDSO page into processes and pass its
* address down to glibc upon exec()?
@@ -71,7 +78,7 @@ EXPORT_SYMBOL_GPL(vdso_enabled);
#endif
static struct page **vdso32_pages;
-static unsigned int vdso32_size;
+static unsigned vdso32_size;
#ifdef CONFIG_X86_64
@@ -117,31 +124,32 @@ void enable_sep_cpu(void)
int __init sysenter_setup(void)
{
- void *vdso_pages;
- const void *vdso;
- size_t vdso_len;
- unsigned int i;
+ char *vdso32_start, *vdso32_end;
+ int npages, i;
+#ifdef CONFIG_COMPAT
if (vdso32_syscall()) {
- vdso = &vdso32_syscall_start;
- vdso_len = &vdso32_syscall_end - &vdso32_syscall_start;
- } else if (vdso32_sysenter()){
- vdso = &vdso32_sysenter_start;
- vdso_len = &vdso32_sysenter_end - &vdso32_sysenter_start;
+ vdso32_start = vdso32_syscall_start;
+ vdso32_end = vdso32_syscall_end;
+ vdso32_pages = vdso32_syscall_pages;
+ } else
+#endif
+ if (vdso32_sysenter()) {
+ vdso32_start = vdso32_sysenter_start;
+ vdso32_end = vdso32_sysenter_end;
+ vdso32_pages = vdso32_sysenter_pages;
} else {
- vdso = &vdso32_int80_start;
- vdso_len = &vdso32_int80_end - &vdso32_int80_start;
+ vdso32_start = vdso32_int80_start;
+ vdso32_end = vdso32_int80_end;
+ vdso32_pages = vdso32_int80_pages;
}
- vdso32_size = (vdso_len + PAGE_SIZE - 1) / PAGE_SIZE;
- vdso32_pages = kmalloc(sizeof(*vdso32_pages) * vdso32_size, GFP_ATOMIC);
- vdso_pages = kmalloc(VDSO_OFFSET(vdso32_size), GFP_ATOMIC);
-
- for(i = 0; i != vdso32_size; ++i)
- vdso32_pages[i] = virt_to_page(vdso_pages + VDSO_OFFSET(i));
+ npages = ((vdso32_end - vdso32_start) + PAGE_SIZE - 1) / PAGE_SIZE;
+ vdso32_size = npages << PAGE_SHIFT;
+ for (i = 0; i < npages; i++)
+ vdso32_pages[i] = virt_to_page(vdso32_start + i*PAGE_SIZE);
- memcpy(vdso_pages, vdso, vdso_len);
- patch_vdso32(vdso_pages, vdso_len);
+ patch_vdso32(vdso32_start, vdso32_size);
return 0;
}
@@ -177,7 +185,7 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
*/
ret = install_special_mapping(mm,
addr,
- VDSO_OFFSET(vdso32_size),
+ vdso32_size,
VM_READ|VM_EXEC|
VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
vdso32_pages);
diff --git a/arch/x86/vdso/vdso32.S b/arch/x86/vdso/vdso32.S
index 2ce5f82..cfa6add 100644
--- a/arch/x86/vdso/vdso32.S
+++ b/arch/x86/vdso/vdso32.S
@@ -1,22 +1,9 @@
-#include <linux/init.h>
+#include "vdso_image.h"
-__INITDATA
+DEFINE_VDSO_IMAGE(vdso32_int80, "arch/x86/vdso/vdso32-int80.so")
- .globl vdso32_int80_start, vdso32_int80_end
-vdso32_int80_start:
- .incbin "arch/x86/vdso/vdso32-int80.so"
-vdso32_int80_end:
-
- .globl vdso32_syscall_start, vdso32_syscall_end
-vdso32_syscall_start:
#ifdef CONFIG_COMPAT
- .incbin "arch/x86/vdso/vdso32-syscall.so"
+DEFINE_VDSO_IMAGE(vdso32_syscall, "arch/x86/vdso/vdso32-syscall.so")
#endif
-vdso32_syscall_end:
-
- .globl vdso32_sysenter_start, vdso32_sysenter_end
-vdso32_sysenter_start:
- .incbin "arch/x86/vdso/vdso32-sysenter.so"
-vdso32_sysenter_end:
-__FINIT
+DEFINE_VDSO_IMAGE(vdso32_sysenter, "arch/x86/vdso/vdso32-sysenter.so")
diff --git a/arch/x86/vdso/vdso_image.h b/arch/x86/vdso/vdso_image.h
new file mode 100644
index 0000000..1baa6bc
--- /dev/null
+++ b/arch/x86/vdso/vdso_image.h
@@ -0,0 +1,30 @@
+#ifndef _VDSO_IMAGE_H
+#define _VDSO_IMAGE_H
+
+#include <asm/page_types.h>
+#include <linux/linkage.h>
+
+#define DEFINE_VDSO_IMAGE(symname, filename) \
+__PAGE_ALIGNED_DATA ; \
+ .globl symname##_start, symname##_end ; \
+ .align PAGE_SIZE ; \
+ symname##_start: ; \
+ .incbin filename ; \
+ symname##_end: ; \
+ .align PAGE_SIZE /* extra data here leaks to userspace. */ ; \
+ \
+.previous ; \
+ \
+ .globl symname##_pages ; \
+ .bss ; \
+ .align 8 ; \
+ .type symname##_pages, @object ; \
+ symname##_pages: ; \
+ .zero (symname##_end - symname##_start + PAGE_SIZE - 1) / PAGE_SIZE * (BITS_PER_LONG / 8) ; \
+ .size symname##_pages, .-symname##_pages
+
+#define DECLARE_VDSO_IMAGE(symname) \
+ extern char symname##_start[], symname##_end[]; \
+ extern struct page *symname##_pages[]
+
+#endif /* _VDSO_IMAGE_H */
diff --git a/arch/x86/vdso/vdsox32.S b/arch/x86/vdso/vdsox32.S
index 295f1c7..19a6927 100644
--- a/arch/x86/vdso/vdsox32.S
+++ b/arch/x86/vdso/vdsox32.S
@@ -1,21 +1,3 @@
-#include <asm/page_types.h>
-#include <linux/linkage.h>
+#include "vdso_image.h"
-__PAGE_ALIGNED_DATA
-
- .globl vdsox32_start, vdsox32_end
- .align PAGE_SIZE
-vdsox32_start:
- .incbin "arch/x86/vdso/vdsox32.so"
-vdsox32_end:
- .align PAGE_SIZE /* extra data here leaks to userspace. */
-
-.previous
-
- .globl vdsox32_pages
- .bss
- .align 8
- .type vdsox32_pages, @object
-vdsox32_pages:
- .zero (vdsox32_end - vdsox32_start + PAGE_SIZE - 1) / PAGE_SIZE * 8
- .size vdsox32_pages, .-vdsox32_pages
+DEFINE_VDSO_IMAGE(vdsox32, "arch/x86/vdso/vdsox32.so")
diff --git a/arch/x86/vdso/vma.c b/arch/x86/vdso/vma.c
index 7345bc9..6db0bbd 100644
--- a/arch/x86/vdso/vma.c
+++ b/arch/x86/vdso/vma.c
@@ -15,19 +15,17 @@
#include <asm/proto.h>
#include <asm/vdso.h>
#include <asm/page.h>
+#include "vdso_image.h"
#if defined(CONFIG_X86_64)
unsigned int __read_mostly vdso_enabled = 1;
-extern char vdso_start[], vdso_end[];
+DECLARE_VDSO_IMAGE(vdso);
extern unsigned short vdso_sync_cpuid;
-
-extern struct page *vdso_pages[];
static unsigned vdso_size;
#ifdef CONFIG_X86_X32_ABI
-extern char vdsox32_start[], vdsox32_end[];
-extern struct page *vdsox32_pages[];
+DECLARE_VDSO_IMAGE(vdsox32);
static unsigned vdsox32_size;
#endif
#endif
--
1.8.5.3
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