5 files changed, 62 insertions, 57 deletions

diff --git a/arch/x86/include/asm/vdso.h b/arch/x86/include/asm/vdso.h
index 30be253dd283..8021bd28c0f1 100644
--- a/arch/x86/include/asm/vdso.h
+++ b/arch/x86/include/asm/vdso.h
@@ -18,15 +18,15 @@ struct vdso_image {
 
         unsigned long alt, alt_len;
 
-        unsigned long sym_end_mapping;  /* Total size of the mapping */
-
-        unsigned long sym_vvar_page;
-        unsigned long sym_hpet_page;
-        unsigned long sym_VDSO32_NOTE_MASK;
-        unsigned long sym___kernel_sigreturn;
-        unsigned long sym___kernel_rt_sigreturn;
-        unsigned long sym___kernel_vsyscall;
-        unsigned long sym_VDSO32_SYSENTER_RETURN;
+        long sym_vvar_start;  /* Negative offset to the vvar area */
+
+        long sym_vvar_page;
+        long sym_hpet_page;
+        long sym_VDSO32_NOTE_MASK;
+        long sym___kernel_sigreturn;
+        long sym___kernel_rt_sigreturn;
+        long sym___kernel_vsyscall;
+        long sym_VDSO32_SYSENTER_RETURN;
 };
 
 #ifdef CONFIG_X86_64
diff --git a/arch/x86/vdso/vdso-layout.lds.S b/arch/x86/vdso/vdso-layout.lds.S
index 9197544eea9a..de2c921025f5 100644
--- a/arch/x86/vdso/vdso-layout.lds.S
+++ b/arch/x86/vdso/vdso-layout.lds.S
@@ -18,6 +18,25 @@
 
 SECTIONS
 {
+        /*
+         * User/kernel shared data is before the vDSO.  This may be a little
+         * uglier than putting it after the vDSO, but it avoids issues with
+         * non-allocatable things that dangle past the end of the PT_LOAD
+         * segment.
+         */
+
+        vvar_start = . - 2 * PAGE_SIZE;
+        vvar_page = vvar_start;
+
+        /* Place all vvars at the offsets in asm/vvar.h. */
+#define EMIT_VVAR(name, offset) vvar_ ## name = vvar_page + offset;
+#define __VVAR_KERNEL_LDS
+#include <asm/vvar.h>
+#undef __VVAR_KERNEL_LDS
+#undef EMIT_VVAR
+
+        hpet_page = vvar_start + PAGE_SIZE;
+
         . = SIZEOF_HEADERS;
 
         .hash           : { *(.hash) }                  :text
@@ -74,31 +93,6 @@ SECTIONS
         .altinstructions        : { *(.altinstructions) }       :text
         .altinstr_replacement   : { *(.altinstr_replacement) }  :text
 
-        /*
-         * The remainder of the vDSO consists of special pages that are
-         * shared between the kernel and userspace.  It needs to be at the
-         * end so that it doesn't overlap the mapping of the actual
-         * vDSO image.
-         */
-
-        . = ALIGN(PAGE_SIZE);
-        vvar_page = .;
-
-        /* Place all vvars at the offsets in asm/vvar.h. */
-#define EMIT_VVAR(name, offset) vvar_ ## name = vvar_page + offset;
-#define __VVAR_KERNEL_LDS
-#include <asm/vvar.h>
-#undef __VVAR_KERNEL_LDS
-#undef EMIT_VVAR
-
-        . = vvar_page + PAGE_SIZE;
-
-        hpet_page = .;
-        . = . + PAGE_SIZE;
-
-        . = ALIGN(PAGE_SIZE);
-        end_mapping = .;
-
         /DISCARD/ : {
                 *(.discard)
                 *(.discard.*)
diff --git a/arch/x86/vdso/vdso2c.c b/arch/x86/vdso/vdso2c.c
index 238dbe82776e..22c54d04bced 100644
--- a/arch/x86/vdso/vdso2c.c
+++ b/arch/x86/vdso/vdso2c.c
@@ -20,9 +20,9 @@ const char *outfilename;
 
 /* Symbols that we need in vdso2c. */
 enum {
+        sym_vvar_start,
         sym_vvar_page,
         sym_hpet_page,
-        sym_end_mapping,
         sym_VDSO_FAKE_SECTION_TABLE_START,
         sym_VDSO_FAKE_SECTION_TABLE_END,
 };
@@ -38,9 +38,9 @@ struct vdso_sym {
 };
 
 struct vdso_sym required_syms[] = {
+        [sym_vvar_start] = {"vvar_start", true},
         [sym_vvar_page] = {"vvar_page", true},
         [sym_hpet_page] = {"hpet_page", true},
-        [sym_end_mapping] = {"end_mapping", true},
         [sym_VDSO_FAKE_SECTION_TABLE_START] = {
                 "VDSO_FAKE_SECTION_TABLE_START", false
         },
@@ -96,9 +96,11 @@ extern void bad_put_le(void);
 
 #define NSYMS (sizeof(required_syms) / sizeof(required_syms[0]))
 
-#define BITSFUNC3(name, bits) name##bits
-#define BITSFUNC2(name, bits) BITSFUNC3(name, bits)
-#define BITSFUNC(name) BITSFUNC2(name, ELF_BITS)
+#define BITSFUNC3(name, bits, suffix) name##bits##suffix
+#define BITSFUNC2(name, bits, suffix) BITSFUNC3(name, bits, suffix)
+#define BITSFUNC(name) BITSFUNC2(name, ELF_BITS, )
+
+#define INT_BITS BITSFUNC2(int, ELF_BITS, _t)
 
 #define ELF_BITS_XFORM2(bits, x) Elf##bits##_##x
 #define ELF_BITS_XFORM(bits, x) ELF_BITS_XFORM2(bits, x)
diff --git a/arch/x86/vdso/vdso2c.h b/arch/x86/vdso/vdso2c.h
index 11b65d4f9414..2da32fbc46da 100644
--- a/arch/x86/vdso/vdso2c.h
+++ b/arch/x86/vdso/vdso2c.h
@@ -132,7 +132,7 @@ static void BITSFUNC(go)(void *addr, size_t len,
                 *alt_sec = NULL;
         ELF(Dyn) *dyn = 0, *dyn_end = 0;
         const char *secstrings;
-        uint64_t syms[NSYMS] = {};
+        INT_BITS syms[NSYMS] = {};
 
         struct BITSFUNC(fake_sections) fake_sections = {};
 
@@ -209,6 +209,13 @@ static void BITSFUNC(go)(void *addr, size_t len,
                                         fail("duplicate symbol %s\n",
                                              required_syms[k].name);
                                 }
+
+                                /*
+                                 * Careful: we use negative addresses, but
+                                 * st_value is unsigned, so we rely
+                                 * on syms[k] being a signed type of the
+                                 * correct width.
+                                 */
                                 syms[k] = GET_LE(&sym->st_value);
                         }
                 }
@@ -263,15 +270,15 @@ static void BITSFUNC(go)(void *addr, size_t len,
                 if (syms[i] % 4096)
                         fail("%s must be a multiple of 4096\n",
                              required_syms[i].name);
-                if (syms[i] < data_size)
-                        fail("%s must be after the text mapping\n",
+                if (syms[sym_vvar_start] > syms[i] + 4096)
+                        fail("%s underruns begin_vvar\n",
                              required_syms[i].name);
-                if (syms[sym_end_mapping] < syms[i] + 4096)
-                        fail("%s overruns end_mapping\n",
+                if (syms[i] + 4096 > 0)
+                        fail("%s is on the wrong side of the vdso text\n",
                              required_syms[i].name);
         }
-        if (syms[sym_end_mapping] % 4096)
-                fail("end_mapping must be a multiple of 4096\n");
+        if (syms[sym_vvar_start] % 4096)
+                fail("vvar_begin must be a multiple of 4096\n");
 
         if (!name) {
                 fwrite(addr, load_size, 1, outfile);
@@ -311,8 +318,8 @@ static void BITSFUNC(go)(void *addr, size_t len,
         }
         for (i = 0; i < NSYMS; i++) {
                 if (required_syms[i].export && syms[i])
-                        fprintf(outfile, "\t.sym_%s = 0x%" PRIx64 ",\n",
-                                required_syms[i].name, syms[i]);
+                        fprintf(outfile, "\t.sym_%s = %" PRIi64 ",\n",
+                                required_syms[i].name, (int64_t)syms[i]);
         }
         fprintf(outfile, "};\n");
 }
diff --git a/arch/x86/vdso/vma.c b/arch/x86/vdso/vma.c
index 5a5176de8d0a..dbef622bb5af 100644
--- a/arch/x86/vdso/vma.c
+++ b/arch/x86/vdso/vma.c
@@ -93,7 +93,7 @@ static int map_vdso(const struct vdso_image *image, bool calculate_addr)
 {
         struct mm_struct *mm = current->mm;
         struct vm_area_struct *vma;
-        unsigned long addr;
+        unsigned long addr, text_start;
         int ret = 0;
         static struct page *no_pages[] = {NULL};
         static struct vm_special_mapping vvar_mapping = {
@@ -103,26 +103,28 @@ static int map_vdso(const struct vdso_image *image, bool calculate_addr)
 
         if (calculate_addr) {
                 addr = vdso_addr(current->mm->start_stack,
-                                 image->sym_end_mapping);
+                                 image->size - image->sym_vvar_start);
         } else {
                 addr = 0;
         }
 
         down_write(&mm->mmap_sem);
 
-        addr = get_unmapped_area(NULL, addr, image->sym_end_mapping, 0, 0);
+        addr = get_unmapped_area(NULL, addr,
+                                 image->size - image->sym_vvar_start, 0, 0);
         if (IS_ERR_VALUE(addr)) {
                 ret = addr;
                 goto up_fail;
         }
 
-        current->mm->context.vdso = (void __user *)addr;
+        text_start = addr - image->sym_vvar_start;
+        current->mm->context.vdso = (void __user *)text_start;
 
         /*
          * MAYWRITE to allow gdb to COW and set breakpoints
          */
         vma = _install_special_mapping(mm,
-                                       addr,
+                                       text_start,
                                        image->size,
                                        VM_READ|VM_EXEC|
                                        VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
@@ -134,8 +136,8 @@ static int map_vdso(const struct vdso_image *image, bool calculate_addr)
         }
 
         vma = _install_special_mapping(mm,
-                                       addr + image->size,
-                                       image->sym_end_mapping - image->size,
+                                       addr,
+                                       -image->sym_vvar_start,
                                        VM_READ,
                                        &vvar_mapping);
 
@@ -146,7 +148,7 @@ static int map_vdso(const struct vdso_image *image, bool calculate_addr)
 
         if (image->sym_vvar_page)
                 ret = remap_pfn_range(vma,
-                                      addr + image->sym_vvar_page,
+                                      text_start + image->sym_vvar_page,
                                       __pa_symbol(&__vvar_page) >> PAGE_SHIFT,
                                       PAGE_SIZE,
                                       PAGE_READONLY);
@@ -157,7 +159,7 @@ static int map_vdso(const struct vdso_image *image, bool calculate_addr)
 #ifdef CONFIG_HPET_TIMER
         if (hpet_address && image->sym_hpet_page) {
                 ret = io_remap_pfn_range(vma,
-                        addr + image->sym_hpet_page,
+                        text_start + image->sym_hpet_page,
                         hpet_address >> PAGE_SHIFT,
                         PAGE_SIZE,
                         pgprot_noncached(PAGE_READONLY));