The patch titled
i386: make COMPAT_VDSO runtime selectable
has been added to the -mm tree. Its filename is
i386-make-compat_vdso-runtime-selectable.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: i386: make COMPAT_VDSO runtime selectable
From: Jeremy Fitzhardinge <jeremy@xxxxxxxx>
Now that relocation of the VDSO for COMPAT_VDSO users is done at runtime
rather than compile time, it is possible to enable/disable compat mode at
runtime.
This patch allows you to enable COMPAT_VDSO mode with "vdso=2" on the kernel
command line, or via sysctl. (Switching on a running system shouldn't be done
lightly; any process which was relying on the compat VDSO will be upset if it
goes away.)
The COMPAT_VDSO config option still exists, but if enabled it just makes
vdso_enabled default to VDSO_COMPAT.
Signed-off-by: Jeremy Fitzhardinge <jeremy@xxxxxxxxxxxxx>
Cc: Zachary Amsden <zach@xxxxxxxxxx>
Cc: "Jan Beulich" <JBeulich@xxxxxxxxxx>
Cc: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>
Cc: Andi Kleen <ak@xxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Roland McGrath <roland@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/kernel-parameters.txt | 1
arch/i386/kernel/sysenter.c | 139 +++++++++++++++++---------
include/asm-i386/page.h | 2
3 files changed, 93 insertions(+), 49 deletions(-)
diff -puN Documentation/kernel-parameters.txt~i386-make-compat_vdso-runtime-selectable Documentation/kernel-parameters.txt
--- a/Documentation/kernel-parameters.txt~i386-make-compat_vdso-runtime-selectable
+++ a/Documentation/kernel-parameters.txt
@@ -1807,6 +1807,7 @@ and is between 256 and 4096 characters.
[USBHID] The interval which mice are to be polled at.
vdso= [IA-32,SH]
+ vdso=2: enable compat VDSO (default with COMPAT_VDSO)
vdso=1: enable VDSO (default)
vdso=0: disable VDSO mapping
diff -puN arch/i386/kernel/sysenter.c~i386-make-compat_vdso-runtime-selectable arch/i386/kernel/sysenter.c
--- a/arch/i386/kernel/sysenter.c~i386-make-compat_vdso-runtime-selectable
+++ a/arch/i386/kernel/sysenter.c
@@ -23,12 +23,25 @@
#include <asm/pgtable.h>
#include <asm/unistd.h>
#include <asm/elf.h>
+#include <asm/tlbflush.h>
+
+enum {
+ VDSO_DISABLED = 0,
+ VDSO_ENABLED = 1,
+ VDSO_COMPAT = 2,
+};
+
+#ifdef CONFIG_COMPAT_VDSO
+#define VDSO_DEFAULT VDSO_COMPAT
+#else
+#define VDSO_DEFAULT VDSO_ENABLED
+#endif
/*
* Should the kernel map a VDSO page into processes and pass its
* address down to glibc upon exec()?
*/
-unsigned int __read_mostly vdso_enabled = 1;
+unsigned int __read_mostly vdso_enabled = VDSO_DEFAULT;
EXPORT_SYMBOL_GPL(vdso_enabled);
@@ -43,7 +56,6 @@ __setup("vdso=", vdso_setup);
extern asmlinkage void sysenter_entry(void);
-#ifdef CONFIG_COMPAT_VDSO
static __init void reloc_symtab(Elf32_Ehdr *ehdr,
unsigned offset, unsigned size)
{
@@ -160,11 +172,6 @@ static __init void relocate_vdso(Elf32_E
shdr[i].sh_size);
}
}
-#else
-static inline void relocate_vdso(Elf32_Ehdr *ehdr)
-{
-}
-#endif /* COMPAT_VDSO */
void enable_sep_cpu(void)
{
@@ -184,6 +191,25 @@ void enable_sep_cpu(void)
put_cpu();
}
+static struct vm_area_struct gate_vma;
+
+static int __init gate_vma_init(void)
+{
+ gate_vma.vm_mm = NULL;
+ gate_vma.vm_start = FIXADDR_USER_START;
+ gate_vma.vm_end = FIXADDR_USER_END;
+ gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC;
+ gate_vma.vm_page_prot = __P101;
+ /*
+ * Make sure the vDSO gets into every core dump.
+ * Dumping its contents makes post-mortem fully interpretable later
+ * without matching up the same kernel and hardware config to see
+ * what PC values meant.
+ */
+ gate_vma.vm_flags |= VM_ALWAYSDUMP;
+ return 0;
+}
+
/*
* These symbols are defined by vsyscall.o to mark the bounds
* of the ELF DSO images included therein.
@@ -192,6 +218,22 @@ extern const char vsyscall_int80_start,
extern const char vsyscall_sysenter_start, vsyscall_sysenter_end;
static struct page *syscall_pages[1];
+static void map_compat_vdso(int map)
+{
+ static int vdso_mapped;
+
+ if (map == vdso_mapped)
+ return;
+
+ vdso_mapped = map;
+
+ __set_fixmap(FIX_VDSO, page_to_pfn(syscall_pages[0]) << PAGE_SHIFT,
+ map ? PAGE_READONLY_EXEC : PAGE_NONE);
+
+ /* flush stray tlbs */
+ flush_tlb_all();
+}
+
int __init sysenter_setup(void)
{
void *syscall_page = (void *)get_zeroed_page(GFP_ATOMIC);
@@ -200,10 +242,9 @@ int __init sysenter_setup(void)
syscall_pages[0] = virt_to_page(syscall_page);
-#ifdef CONFIG_COMPAT_VDSO
- __set_fixmap(FIX_VDSO, __pa(syscall_page), PAGE_READONLY_EXEC);
+ gate_vma_init();
+
printk("Compat vDSO mapped to %08lx.\n", __fix_to_virt(FIX_VDSO));
-#endif
if (!boot_cpu_has(X86_FEATURE_SEP)) {
vsyscall = &vsyscall_int80_start;
@@ -222,42 +263,57 @@ int __init sysenter_setup(void)
/* Defined in vsyscall-sysenter.S */
extern void SYSENTER_RETURN;
-#ifdef __HAVE_ARCH_GATE_AREA
/* Setup a VMA at program startup for the vsyscall page */
int arch_setup_additional_pages(struct linux_binprm *bprm, int exstack)
{
struct mm_struct *mm = current->mm;
unsigned long addr;
int ret;
+ bool compat;
down_write(&mm->mmap_sem);
- addr = get_unmapped_area(NULL, 0, PAGE_SIZE, 0, 0);
- if (IS_ERR_VALUE(addr)) {
- ret = addr;
- goto up_fail;
- }
- /*
- * MAYWRITE to allow gdb to COW and set breakpoints
- *
- * Make sure the vDSO gets into every core dump.
- * Dumping its contents makes post-mortem fully interpretable later
- * without matching up the same kernel and hardware config to see
- * what PC values meant.
- */
- ret = install_special_mapping(mm, addr, PAGE_SIZE,
- VM_READ|VM_EXEC|
- VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC|
- VM_ALWAYSDUMP,
- syscall_pages);
- if (ret)
- goto up_fail;
+ /* Test compat mode once here, in case someone
+ changes it via sysctl */
+ compat = (vdso_enabled == VDSO_COMPAT);
+
+ map_compat_vdso(compat);
+
+ if (compat)
+ addr = VDSO_HIGH_BASE;
+ else {
+ addr = get_unmapped_area(NULL, 0, PAGE_SIZE, 0, 0);
+ if (IS_ERR_VALUE(addr)) {
+ ret = addr;
+ goto up_fail;
+ }
+
+ /*
+ * MAYWRITE to allow gdb to COW and set breakpoints
+ *
+ * Make sure the vDSO gets into every core dump.
+ * Dumping its contents makes post-mortem fully
+ * interpretable later without matching up the same
+ * kernel and hardware config to see what PC values
+ * meant.
+ */
+ ret = install_special_mapping(mm, addr, PAGE_SIZE,
+ VM_READ|VM_EXEC|
+ VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC|
+ VM_ALWAYSDUMP,
+ syscall_pages);
+
+ if (ret)
+ goto up_fail;
+ }
current->mm->context.vdso = (void *)addr;
current_thread_info()->sysenter_return =
- (void *)VDSO_SYM(&SYSENTER_RETURN);
-up_fail:
+ (void *)VDSO_SYM(&SYSENTER_RETURN);
+
+ up_fail:
up_write(&mm->mmap_sem);
+
return ret;
}
@@ -270,6 +326,9 @@ const char *arch_vma_name(struct vm_area
struct vm_area_struct *get_gate_vma(struct task_struct *tsk)
{
+ /* Check to see if this task was created in compat vdso mode */
+ if (tsk->mm->context.vdso == (void *)VDSO_HIGH_BASE)
+ return &gate_vma;
return NULL;
}
@@ -282,17 +341,3 @@ int in_gate_area_no_task(unsigned long a
{
return 0;
}
-#else /* !__HAVE_ARCH_GATE_AREA */
-int arch_setup_additional_pages(struct linux_binprm *bprm, int exstack)
-{
- /*
- * If not creating userspace VMA, simply set vdso to point to
- * fixmap page.
- */
- current->mm->context.vdso = (void *)VDSO_HIGH_BASE;
- current_thread_info()->sysenter_return =
- (void *)VDSO_SYM(&SYSENTER_RETURN);
-
- return 0;
-}
-#endif /* __HAVE_ARCH_GATE_AREA */
diff -puN include/asm-i386/page.h~i386-make-compat_vdso-runtime-selectable include/asm-i386/page.h
--- a/include/asm-i386/page.h~i386-make-compat_vdso-runtime-selectable
+++ a/include/asm-i386/page.h
@@ -143,9 +143,7 @@ extern int page_is_ram(unsigned long pag
#include <asm-generic/memory_model.h>
#include <asm-generic/page.h>
-#ifndef CONFIG_COMPAT_VDSO
#define __HAVE_ARCH_GATE_AREA 1
-#endif
#endif /* __KERNEL__ */
#endif /* _I386_PAGE_H */
_
Patches currently in -mm which might be from jeremy@xxxxxxxx are
proper-fix-for-highmem-kmap_atomic-functions-for-vmi-for-2621.patch
revert-proper-fix-for-highmem-kmap_atomic-functions-for-vmi-for-2621.patch
re-enable-vdso-by-default-with-paravirt.patch
remove-noreplacement-option.patch
remove-smp_alt_instructions.patch
rename-the-parainstructions-symbols-to-be-consistent-with-the-others.patch
allow-boot-time-disable-of-smp-altinstructions.patch
allow-boot-time-disable-of-paravirt_ops-patching.patch
i386-clean-up-asm-i386-bugsh.patch
i386-clean-up-identify_cpu.patch
i386-relocate-vdso-elf-headers-to-match-mapped-location-with-compat_vdso.patch
i386-make-compat_vdso-runtime-selectable.patch
maps2-uninline-some-functions-in-the-page-walker.patch
maps2-eliminate-the-pmd_walker-struct-in-the-page-walker.patch
maps2-remove-vma-from-args-in-the-page-walker.patch
maps2-propagate-errors-from-callback-in-page-walker.patch
maps2-add-callbacks-for-each-level-to-page-walker.patch
maps2-move-the-page-walker-code-to-lib.patch
maps2-simplify-interdependence-of-proc-pid-maps-and-smaps.patch
maps2-move-clear_refs-code-to-task_mmuc.patch
maps2-regroup-task_mmu-by-interface.patch
maps2-make-proc-pid-smaps-optional-under-config_embedded.patch
maps2-make-proc-pid-clear_refs-option-under-config_embedded.patch
maps2-add-proc-pid-pagemap-interface.patch
maps2-add-proc-kpagemap-interface.patch
fixes-and-cleanups-for-earlyprintk-aka-boot-console.patch
ignore-stolen-time-in-the-softlockup-watchdog.patch
add-touch_all_softlockup_watchdogs.patch
clean-up-elf-note-generation.patch
-
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