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Subject[RFC v17][PATCH 01/60] c/r: extend arch_setup_additional_pages()
Date
From: Alexey Dobriyan <adobriyan@gmail.com>

Add "start" argument, to request to map vDSO to a specific place,
and fail the operation if not.

This is useful for restart(2) to ensure that memory layout is restore
exactly as needed.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Oren Laadan <orenl@cs.columbia.edu>
---
arch/powerpc/include/asm/elf.h | 1 +
arch/powerpc/kernel/vdso.c | 13 ++++++++++++-
arch/s390/include/asm/elf.h | 2 +-
arch/s390/kernel/vdso.c | 13 ++++++++++++-
arch/sh/include/asm/elf.h | 1 +
arch/sh/kernel/vsyscall/vsyscall.c | 2 +-
arch/x86/include/asm/elf.h | 3 ++-
arch/x86/vdso/vdso32-setup.c | 9 +++++++--
arch/x86/vdso/vma.c | 9 +++++++--
fs/binfmt_elf.c | 2 +-
10 files changed, 45 insertions(+), 10 deletions(-)

diff --git a/arch/powerpc/include/asm/elf.h b/arch/powerpc/include/asm/elf.h
index 014a624..3cef9cf 100644
--- a/arch/powerpc/include/asm/elf.h
+++ b/arch/powerpc/include/asm/elf.h
@@ -271,6 +271,7 @@ extern int ucache_bsize;
#define ARCH_HAS_SETUP_ADDITIONAL_PAGES
struct linux_binprm;
extern int arch_setup_additional_pages(struct linux_binprm *bprm,
+ unsigned long start,
int uses_interp);
#define VDSO_AUX_ENT(a,b) NEW_AUX_ENT(a,b);

diff --git a/arch/powerpc/kernel/vdso.c b/arch/powerpc/kernel/vdso.c
index ad06d5c..c25213b 100644
--- a/arch/powerpc/kernel/vdso.c
+++ b/arch/powerpc/kernel/vdso.c
@@ -184,7 +184,8 @@ static void dump_vdso_pages(struct vm_area_struct * vma)
* This is called from binfmt_elf, we create the special vma for the
* vDSO and insert it into the mm struct tree
*/
-int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
+int arch_setup_additional_pages(struct linux_binprm *bprm,
+ unsigned long start, int uses_interp)
{
struct mm_struct *mm = current->mm;
struct page **vdso_pagelist;
@@ -211,6 +212,10 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
vdso_base = VDSO32_MBASE;
#endif

+ /* in case restart(2) mandates a specific location */
+ if (start)
+ vdso_base = start;
+
current->mm->context.vdso_base = 0;

/* vDSO has a problem and was disabled, just don't "enable" it for the
@@ -234,6 +239,12 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
goto fail_mmapsem;
}

+ /* for restart(2), double check that we got we asked for */
+ if (start && vdso_base != start) {
+ ret = -EBUSY;
+ goto fail_mmapsem;
+ }
+
/*
* our vma flags don't have VM_WRITE so by default, the process isn't
* allowed to write those pages.
diff --git a/arch/s390/include/asm/elf.h b/arch/s390/include/asm/elf.h
index 74d0bbb..54235bc 100644
--- a/arch/s390/include/asm/elf.h
+++ b/arch/s390/include/asm/elf.h
@@ -205,6 +205,6 @@ do { \
struct linux_binprm;

#define ARCH_HAS_SETUP_ADDITIONAL_PAGES 1
-int arch_setup_additional_pages(struct linux_binprm *, int);
+int arch_setup_additional_pages(struct linux_binprm *, unsigned long, int);

#endif
diff --git a/arch/s390/kernel/vdso.c b/arch/s390/kernel/vdso.c
index 45e1708..c2ee689 100644
--- a/arch/s390/kernel/vdso.c
+++ b/arch/s390/kernel/vdso.c
@@ -193,7 +193,8 @@ static void vdso_init_cr5(void)
* This is called from binfmt_elf, we create the special vma for the
* vDSO and insert it into the mm struct tree
*/
-int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
+int arch_setup_additional_pages(struct linux_binprm *bprm,
+ unsigned long start, int uses_interp)
{
struct mm_struct *mm = current->mm;
struct page **vdso_pagelist;
@@ -224,6 +225,10 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
vdso_pages = vdso32_pages;
#endif

+ /* in case restart(2) mandates a specific location */
+ if (start)
+ vdso_base = start;
+
/*
* vDSO has a problem and was disabled, just don't "enable" it for
* the process
@@ -246,6 +251,12 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
goto out_up;
}

+ /* for restart(2), double check that we got we asked for */
+ if (start && vdso_base != start) {
+ rc = -EINVAL;
+ goto out_up;
+ }
+
/*
* our vma flags don't have VM_WRITE so by default, the process
* isn't allowed to write those pages.
diff --git a/arch/sh/include/asm/elf.h b/arch/sh/include/asm/elf.h
index ccb1d93..6c27b1f 100644
--- a/arch/sh/include/asm/elf.h
+++ b/arch/sh/include/asm/elf.h
@@ -202,6 +202,7 @@ do { \
#define ARCH_HAS_SETUP_ADDITIONAL_PAGES
struct linux_binprm;
extern int arch_setup_additional_pages(struct linux_binprm *bprm,
+ unsigned long start,
int uses_interp);

extern unsigned int vdso_enabled;
diff --git a/arch/sh/kernel/vsyscall/vsyscall.c b/arch/sh/kernel/vsyscall/vsyscall.c
index 3f7e415..64c70e5 100644
--- a/arch/sh/kernel/vsyscall/vsyscall.c
+++ b/arch/sh/kernel/vsyscall/vsyscall.c
@@ -59,7 +59,7 @@ int __init vsyscall_init(void)
}

/* Setup a VMA at program startup for the vsyscall page */
-int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
+int arch_setup_additional_pages(struct linux_binprm *bprm, unsigned long start, int uses_interp)
{
struct mm_struct *mm = current->mm;
unsigned long addr;
diff --git a/arch/x86/include/asm/elf.h b/arch/x86/include/asm/elf.h
index 83c1bc8..a4398c8 100644
--- a/arch/x86/include/asm/elf.h
+++ b/arch/x86/include/asm/elf.h
@@ -336,9 +336,10 @@ struct linux_binprm;

#define ARCH_HAS_SETUP_ADDITIONAL_PAGES 1
extern int arch_setup_additional_pages(struct linux_binprm *bprm,
+ unsigned long start,
int uses_interp);

-extern int syscall32_setup_pages(struct linux_binprm *, int exstack);
+extern int syscall32_setup_pages(struct linux_binprm *, unsigned long start, int exstack);
#define compat_arch_setup_additional_pages syscall32_setup_pages

extern unsigned long arch_randomize_brk(struct mm_struct *mm);
diff --git a/arch/x86/vdso/vdso32-setup.c b/arch/x86/vdso/vdso32-setup.c
index 58bc00f..5c914b0 100644
--- a/arch/x86/vdso/vdso32-setup.c
+++ b/arch/x86/vdso/vdso32-setup.c
@@ -310,7 +310,8 @@ int __init sysenter_setup(void)
}

/* Setup a VMA at program startup for the vsyscall page */
-int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
+int arch_setup_additional_pages(struct linux_binprm *bprm,
+ unsigned long start, int uses_interp)
{
struct mm_struct *mm = current->mm;
unsigned long addr;
@@ -331,13 +332,17 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
if (compat)
addr = VDSO_HIGH_BASE;
else {
- addr = get_unmapped_area(NULL, 0, PAGE_SIZE, 0, 0);
+ addr = get_unmapped_area(NULL, start, PAGE_SIZE, 0, 0);
if (IS_ERR_VALUE(addr)) {
ret = addr;
goto up_fail;
}
}

+ /* for restart(2), double check that we got we asked for */
+ if (start && addr != start)
+ goto up_fail;
+
current->mm->context.vdso = (void *)addr;

if (compat_uses_vma || !compat) {
diff --git a/arch/x86/vdso/vma.c b/arch/x86/vdso/vma.c
index 21e1aeb..393b22a 100644
--- a/arch/x86/vdso/vma.c
+++ b/arch/x86/vdso/vma.c
@@ -99,7 +99,8 @@ static unsigned long vdso_addr(unsigned long start, unsigned len)

/* Setup a VMA at program startup for the vsyscall page.
Not called for compat tasks */
-int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
+int arch_setup_additional_pages(struct linux_binprm *bprm,
+ unsigned long start, int uses_interp)
{
struct mm_struct *mm = current->mm;
unsigned long addr;
@@ -109,13 +110,17 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
return 0;

down_write(&mm->mmap_sem);
- addr = vdso_addr(mm->start_stack, vdso_size);
+ addr = start ? : vdso_addr(mm->start_stack, vdso_size);
addr = get_unmapped_area(NULL, addr, vdso_size, 0, 0);
if (IS_ERR_VALUE(addr)) {
ret = addr;
goto up_fail;
}

+ /* for restart(2), double check that we got we asked for */
+ if (start && addr != start)
+ goto up_fail;
+
current->mm->context.vdso = (void *)addr;

ret = install_special_mapping(mm, addr, vdso_size,
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index b7c1603..14a1b3c 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -945,7 +945,7 @@ static int load_elf_binary(struct linux_binprm *bprm, struct pt_regs *regs)
set_binfmt(&elf_format);

#ifdef ARCH_HAS_SETUP_ADDITIONAL_PAGES
- retval = arch_setup_additional_pages(bprm, !!elf_interpreter);
+ retval = arch_setup_additional_pages(bprm, 0, !!elf_interpreter);
if (retval < 0) {
send_sig(SIGKILL, current, 0);
goto out;
--
1.6.0.4


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