x86: Load the 32-bit vdso in place, just like the 64-bit vdsos

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@amacapital.net>
Cc: Stefani Seibold <stefani@seibold.net>
Link: http://lkml.kernel.org/r/b8093933fad09ce181edb08a61dcd5d2592e9814.1395352498.git.luto@amacapital.net
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

diff --git a/arch/x86/include/asm/vdso.h b/arch/x86/include/asm/vdso.h
index bde4359..0301d78 100644 (file)
--- 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 (file)
--- 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 (file)
--- 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 (file)
--- 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 (file)
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 (file)
--- 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 (file)
--- 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