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Subject[PATCH 2/4] coredump: ELF: enable to omit anonymous shared memory
This patch enables to omit anonymous shared memory from an ELF
formatted core file when it is generated.

Signed-off-by: Hidehiro Kawai <hidehiro.kawai.ez@hitachi.com>
---
fs/binfmt_elf.c | 20 ++++++++++++++------
1 files changed, 14 insertions(+), 6 deletions(-)

Index: linux-2.6.20-mm1/fs/binfmt_elf.c
===================================================================
--- linux-2.6.20-mm1.orig/fs/binfmt_elf.c
+++ linux-2.6.20-mm1/fs/binfmt_elf.c
@@ -1181,7 +1181,7 @@ static int dump_seek(struct file *file,
*
* I think we should skip something. But I am not sure how. H.J.
*/
-static int maydump(struct vm_area_struct *vma)
+static int maydump(struct vm_area_struct *vma, unsigned int omit_anon_shared)
{
/* The vma can be set up to tell us the answer directly. */
if (vma->vm_flags & VM_ALWAYSDUMP)
@@ -1191,9 +1191,15 @@ static int maydump(struct vm_area_struct
if (vma->vm_flags & (VM_IO | VM_RESERVED))
return 0;

- /* Dump shared memory only if mapped from an anonymous file. */
- if (vma->vm_flags & VM_SHARED)
- return vma->vm_file->f_path.dentry->d_inode->i_nlink == 0;
+ /*
+ * Dump shared memory only if mapped from an anonymous file and
+ * /proc/<pid>/coredump_omit_anonymous_shared flag is not set.
+ */
+ if (vma->vm_flags & VM_SHARED) {
+ if (vma->vm_file->f_path.dentry->d_inode->i_nlink)
+ return 0;
+ return omit_anon_shared == 0;
+ }

/* If it hasn't been written to, don't write it out */
if (!vma->anon_vma)
@@ -1491,6 +1497,7 @@ static int elf_core_dump(long signr, str
#endif
int thread_status_size = 0;
elf_addr_t *auxv;
+ unsigned int omit_anon_shared = 0;

/*
* We no longer stop all VM operations.
@@ -1629,6 +1636,7 @@ static int elf_core_dump(long signr, str
}

dataoff = offset = roundup(offset, ELF_EXEC_PAGESIZE);
+ omit_anon_shared = current->mm->coredump_omit_anon_shared;

/* Write program headers for segments dump */
for (vma = first_vma(current, gate_vma); vma != NULL;
@@ -1642,7 +1650,7 @@ static int elf_core_dump(long signr, str
phdr.p_offset = offset;
phdr.p_vaddr = vma->vm_start;
phdr.p_paddr = 0;
- phdr.p_filesz = maydump(vma) ? sz : 0;
+ phdr.p_filesz = maydump(vma, omit_anon_shared) ? sz : 0;
phdr.p_memsz = sz;
offset += phdr.p_filesz;
phdr.p_flags = vma->vm_flags & VM_READ ? PF_R : 0;
@@ -1685,7 +1693,7 @@ static int elf_core_dump(long signr, str
vma = next_vma(vma, gate_vma)) {
unsigned long addr;

- if (!maydump(vma))
+ if (!maydump(vma, omit_anon_shared))
continue;

for (addr = vma->vm_start;

-
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