Re: [PATCH 1/2] core dump: drop VM_ALWAYSDUMP flag
From: Jason Baron
Date: Wed Mar 07 2012 - 16:19:19 EST
On Wed, Mar 07, 2012 at 11:43:02AM -0800, Roland McGrath wrote:
> > well, sure, we can provide an arch interface, for this check. I'm more
> > concerned with the general idea. If it seems ok, I can re-do this bit
> > with an arch interface.
>
> Anything based on strcmp is dismal. VM_ALWAYSDUMP was nice and clean.
> A hook along the lines of arch_vma_name would be clean enough I suppose.
> In fact, there is only one instance today (tile) where arch_vma_name()!=NULL
> wouldn't do just what you need.
>
Yeah, so I think something like the following would work (adding Tile
maintainer to 'cc list).
Thanks,
-Jason
The VM_ALWAYSDUMP flag is currently used by the coredump code to indicate that
a vma is part of a vsyscall or vdso section, and then always dump it. However, we
can determine if a vma is in one of these sections by using 'arch_vma_name()',
and thus re-purpose a valuable vma bit.
Signed-off-by: Jason Baron <jbaron@xxxxxxxxxx>
---
arch/arm/kernel/process.c | 2 +-
arch/hexagon/kernel/vdso.c | 3 +--
arch/mips/kernel/vdso.c | 3 +--
arch/powerpc/kernel/vdso.c | 3 +--
arch/s390/kernel/vdso.c | 3 +--
arch/sh/kernel/vsyscall/vsyscall.c | 3 +--
arch/tile/mm/elf.c | 3 +--
arch/unicore32/kernel/process.c | 2 +-
arch/x86/um/mem_32.c | 8 --------
arch/x86/um/vdso/vma.c | 3 +--
arch/x86/vdso/vdso32-setup.c | 11 ++---------
arch/x86/vdso/vma.c | 3 +--
fs/binfmt_elf.c | 22 ++++++++++++++++++++--
include/linux/mm.h | 1 -
mm/memory.c | 8 +-------
15 files changed, 33 insertions(+), 45 deletions(-)
diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
index 971d65c..565ac89 100644
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -536,7 +536,7 @@ int vectors_user_mapping(void)
return install_special_mapping(mm, 0xffff0000, PAGE_SIZE,
VM_READ | VM_EXEC |
VM_MAYREAD | VM_MAYEXEC |
- VM_ALWAYSDUMP | VM_RESERVED,
+ VM_RESERVED,
NULL);
}
diff --git a/arch/hexagon/kernel/vdso.c b/arch/hexagon/kernel/vdso.c
index 16277c3..f212a45 100644
--- a/arch/hexagon/kernel/vdso.c
+++ b/arch/hexagon/kernel/vdso.c
@@ -78,8 +78,7 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
/* MAYWRITE to allow gdb to COW and set breakpoints. */
ret = install_special_mapping(mm, vdso_base, PAGE_SIZE,
VM_READ|VM_EXEC|
- VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC|
- VM_ALWAYSDUMP,
+ VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
&vdso_page);
if (ret)
diff --git a/arch/mips/kernel/vdso.c b/arch/mips/kernel/vdso.c
index e5cdfd6..0f1af58 100644
--- a/arch/mips/kernel/vdso.c
+++ b/arch/mips/kernel/vdso.c
@@ -88,8 +88,7 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
ret = install_special_mapping(mm, addr, PAGE_SIZE,
VM_READ|VM_EXEC|
- VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC|
- VM_ALWAYSDUMP,
+ VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
&vdso_page);
if (ret)
diff --git a/arch/powerpc/kernel/vdso.c b/arch/powerpc/kernel/vdso.c
index 7d14bb6..af58021 100644
--- a/arch/powerpc/kernel/vdso.c
+++ b/arch/powerpc/kernel/vdso.c
@@ -272,8 +272,7 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
*/
rc = install_special_mapping(mm, vdso_base, vdso_pages << PAGE_SHIFT,
VM_READ|VM_EXEC|
- VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC|
- VM_ALWAYSDUMP,
+ VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
vdso_pagelist);
if (rc) {
current->mm->context.vdso_base = 0;
diff --git a/arch/s390/kernel/vdso.c b/arch/s390/kernel/vdso.c
index d73630b..25c838c 100644
--- a/arch/s390/kernel/vdso.c
+++ b/arch/s390/kernel/vdso.c
@@ -262,8 +262,7 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
*/
rc = install_special_mapping(mm, vdso_base, vdso_pages << PAGE_SHIFT,
VM_READ|VM_EXEC|
- VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC|
- VM_ALWAYSDUMP,
+ VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
vdso_pagelist);
if (rc)
current->mm->context.vdso_base = 0;
diff --git a/arch/sh/kernel/vsyscall/vsyscall.c b/arch/sh/kernel/vsyscall/vsyscall.c
index 1d6d51a..5ca5797 100644
--- a/arch/sh/kernel/vsyscall/vsyscall.c
+++ b/arch/sh/kernel/vsyscall/vsyscall.c
@@ -73,8 +73,7 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
ret = install_special_mapping(mm, addr, PAGE_SIZE,
VM_READ | VM_EXEC |
- VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC |
- VM_ALWAYSDUMP,
+ VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC,
syscall_pages);
if (unlikely(ret))
goto up_fail;
diff --git a/arch/tile/mm/elf.c b/arch/tile/mm/elf.c
index 55e58e9..c4b3ed8 100644
--- a/arch/tile/mm/elf.c
+++ b/arch/tile/mm/elf.c
@@ -126,8 +126,7 @@ int arch_setup_additional_pages(struct linux_binprm *bprm,
vdso_base = VDSO_BASE;
retval = install_special_mapping(mm, vdso_base, PAGE_SIZE,
VM_READ|VM_EXEC|
- VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC|
- VM_ALWAYSDUMP,
+ VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
vdso_pages);
#ifndef __tilegx__
diff --git a/arch/unicore32/kernel/process.c b/arch/unicore32/kernel/process.c
index 52edc2b..432b429 100644
--- a/arch/unicore32/kernel/process.c
+++ b/arch/unicore32/kernel/process.c
@@ -381,7 +381,7 @@ int vectors_user_mapping(void)
return install_special_mapping(mm, 0xffff0000, PAGE_SIZE,
VM_READ | VM_EXEC |
VM_MAYREAD | VM_MAYEXEC |
- VM_ALWAYSDUMP | VM_RESERVED,
+ VM_RESERVED,
NULL);
}
diff --git a/arch/x86/um/mem_32.c b/arch/x86/um/mem_32.c
index 639900a..f40281e 100644
--- a/arch/x86/um/mem_32.c
+++ b/arch/x86/um/mem_32.c
@@ -23,14 +23,6 @@ static int __init gate_vma_init(void)
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;
}
__initcall(gate_vma_init);
diff --git a/arch/x86/um/vdso/vma.c b/arch/x86/um/vdso/vma.c
index 91f4ec9..af91901 100644
--- a/arch/x86/um/vdso/vma.c
+++ b/arch/x86/um/vdso/vma.c
@@ -64,8 +64,7 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
err = install_special_mapping(mm, um_vdso_addr, PAGE_SIZE,
VM_READ|VM_EXEC|
- VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC|
- VM_ALWAYSDUMP,
+ VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
vdsop);
up_write(&mm->mmap_sem);
diff --git a/arch/x86/vdso/vdso32-setup.c b/arch/x86/vdso/vdso32-setup.c
index 468d591..b4d43dd 100644
--- a/arch/x86/vdso/vdso32-setup.c
+++ b/arch/x86/vdso/vdso32-setup.c
@@ -250,13 +250,7 @@ static int __init gate_vma_init(void)
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;
}
@@ -352,8 +346,7 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
*/
ret = install_special_mapping(mm, addr, PAGE_SIZE,
VM_READ|VM_EXEC|
- VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC|
- VM_ALWAYSDUMP,
+ VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
vdso32_pages);
if (ret)
diff --git a/arch/x86/vdso/vma.c b/arch/x86/vdso/vma.c
index 153407c..17e1827 100644
--- a/arch/x86/vdso/vma.c
+++ b/arch/x86/vdso/vma.c
@@ -124,8 +124,7 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
ret = install_special_mapping(mm, addr, vdso_size,
VM_READ|VM_EXEC|
- VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC|
- VM_ALWAYSDUMP,
+ VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
vdso_pages);
if (ret) {
current->mm->context.vdso = NULL;
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index 07d096c..8a90861 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -1094,6 +1094,24 @@ out:
* Jeremy Fitzhardinge <jeremy@xxxxxxxx>
*/
+/* Determine if the vma should always be output in the coredump */
+static bool always_dump_vma(struct vm_area_struct *vma)
+{
+ const char *vma_name = arch_vma_name(vma);
+
+ if (vma_name) {
+#ifdef CONFIG_TILE
+ /* Tile user-interrupt mapping which we don't always dump */
+ if (is_arch_mappable_range(vma->vm_start, 0))
+ return false;
+#endif
+ return true;
+ }
+ if (vma == get_gate_vma(vma->vm_mm))
+ return true;
+ return false;
+}
+
/*
* Decide what to dump of a segment, part, all or none.
*/
@@ -1102,8 +1120,8 @@ static unsigned long vma_dump_size(struct vm_area_struct *vma,
{
#define FILTER(type) (mm_flags & (1UL << MMF_DUMP_##type))
- /* The vma can be set up to tell us the answer directly. */
- if (vma->vm_flags & VM_ALWAYSDUMP)
+ /* always dump the vdso and vsyscall sections */
+ if (always_dump_vma(vma))
goto whole;
/* Hugetlb memory check */
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 17b27cd..a296709 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -111,7 +111,6 @@ extern unsigned int kobjsize(const void *objp);
#define VM_HUGEPAGE 0x01000000 /* MADV_HUGEPAGE marked this vma */
#endif
#define VM_INSERTPAGE 0x02000000 /* The vma has had "vm_insert_page()" done on it */
-#define VM_ALWAYSDUMP 0x04000000 /* Always include in core dumps */
#define VM_CAN_NONLINEAR 0x08000000 /* Has ->fault & does nonlinear pages */
#define VM_MIXEDMAP 0x10000000 /* Can contain "struct page" and pure PFN pages */
diff --git a/mm/memory.c b/mm/memory.c
index fa2f04e..9b55ab0 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3611,13 +3611,7 @@ static int __init gate_vma_init(void)
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;
}
__initcall(gate_vma_init);
--
1.7.7.6
--
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