lkml.org 
[lkml]   [2003]   [Mar]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[PATCH] reduce stack size: elf_core_dump()
Hi,

This patch reduces stack size in elf_core_dump() from
over 0x400 (0x4a4 e.g.) to less than 0x100 (0xb0 on a P4
with gcc 2.96).

Patch applies to 2.5.64. Please apply.

Thanks,
~Randypatch_name: binfmtelf_stack.patch
patch_version: 2003-03-01.19:59:53
author: Randy.Dunlap <rddunlap@osdl.org>
description: reduce large stack usage in elf_core_dump();
product: Linux
product_versions: linux-2563 and linux-2564
changelog: _
URL: _
requires: _
conflicts: _
diffstat: =
fs/binfmt_elf.c | 108 +++++++++++++++++++++++++++++++++++---------------------
1 files changed, 68 insertions(+), 40 deletions(-)


diff -Naur ./fs/binfmt_elf.c%STK ./fs/binfmt_elf.c
--- ./fs/binfmt_elf.c%STK Mon Feb 24 11:05:31 2003
+++ ./fs/binfmt_elf.c Sat Mar 1 19:59:14 2003
@@ -10,7 +10,7 @@
*/

#include <linux/module.h>
-
+#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/stat.h>
#include <linux/time.h>
@@ -1175,41 +1175,62 @@
*/
static int elf_core_dump(long signr, struct pt_regs * regs, struct file * file)
{
+#define NUM_NOTES 5
int has_dumped = 0;
mm_segment_t fs;
int segs;
size_t size = 0;
int i;
struct vm_area_struct *vma;
- struct elfhdr elf;
+ struct elfhdr *elf = NULL;
off_t offset = 0, dataoff;
unsigned long limit = current->rlim[RLIMIT_CORE].rlim_cur;
- int numnote = 5;
- struct memelfnote notes[5];
- struct elf_prstatus prstatus; /* NT_PRSTATUS */
- struct elf_prpsinfo psinfo; /* NT_PRPSINFO */
+ int numnote = NUM_NOTES;
+ struct memelfnote *notes = NULL;
+ struct elf_prstatus *prstatus = NULL; /* NT_PRSTATUS */
+ struct elf_prpsinfo *psinfo = NULL; /* NT_PRPSINFO */
struct task_struct *g, *p;
LIST_HEAD(thread_list);
struct list_head *t;
- elf_fpregset_t fpu;
-#ifdef ELF_CORE_COPY_XFPREGS
- elf_fpxregset_t xfpu;
-#endif
+ elf_fpregset_t *fpu = NULL;
+ elf_fpxregset_t *xfpu = NULL;
int thread_status_size = 0;
-
- /* We no longer stop all vm operations
+
+ /*
+ * We no longer stop all VM operations.
*
- * This because those proceses that could possibly
- * change map_count or the mmap / vma pages are now blocked in do_exit on current finishing
+ * This is because those proceses that could possibly change map_count or
+ * the mmap / vma pages are now blocked in do_exit on current finishing
* this core dump.
*
* Only ptrace can touch these memory addresses, but it doesn't change
- * the map_count or the pages allocated. So no possibility of crashing exists while dumping
- * the mm->vm_next areas to the core file.
- *
+ * the map_count or the pages allocated. So no possibility of crashing
+ * exists while dumping the mm->vm_next areas to the core file.
*/
-
- /* capture the status of all other threads */
+
+ /* alloc memory for large data structures: too large to be on stack */
+ elf = kmalloc(sizeof(*elf), GFP_KERNEL);
+ if (!elf)
+ goto cleanup;
+ prstatus = kmalloc(sizeof(*prstatus), GFP_KERNEL);
+ if (!prstatus)
+ goto cleanup;
+ psinfo = kmalloc(sizeof(*psinfo), GFP_KERNEL);
+ if (!psinfo)
+ goto cleanup;
+ notes = kmalloc(NUM_NOTES * sizeof(struct memelfnote), GFP_KERNEL);
+ if (!notes)
+ goto cleanup;
+ fpu = kmalloc(sizeof(*fpu), GFP_KERNEL);
+ if (!fpu)
+ goto cleanup;
+#ifdef ELF_CORE_COPY_XFPREGS
+ xfpu = kmalloc(sizeof(*xfpu), GFP_KERNEL);
+ if (!xfpu)
+ goto cleanup;
+#endif
+
+ /* capture the status of all other threads */
if (signr) {
read_lock(&tasklist_lock);
do_each_thread(g,p)
@@ -1226,14 +1247,14 @@
}

/* now collect the dump for the current */
- memset(&prstatus, 0, sizeof(prstatus));
- fill_prstatus(&prstatus, current, signr);
- elf_core_copy_regs(&prstatus.pr_reg, regs);
+ memset(prstatus, 0, sizeof(*prstatus));
+ fill_prstatus(prstatus, current, signr);
+ elf_core_copy_regs(&prstatus->pr_reg, regs);

segs = current->mm->map_count;

/* Set up header */
- fill_elf_header(&elf, segs+1); /* including notes section*/
+ fill_elf_header(elf, segs+1); /* including notes section */

has_dumped = 1;
current->flags |= PF_DUMPCORE;
@@ -1243,32 +1264,32 @@
* with info from their /proc.
*/

- fill_note(&notes[0], "CORE", NT_PRSTATUS, sizeof(prstatus), &prstatus);
+ fill_note(notes +0, "CORE", NT_PRSTATUS, sizeof(*prstatus), prstatus);

- fill_psinfo(&psinfo, current->group_leader);
- fill_note(&notes[1], "CORE", NT_PRPSINFO, sizeof(psinfo), &psinfo);
+ fill_psinfo(psinfo, current->group_leader);
+ fill_note(notes +1, "CORE", NT_PRPSINFO, sizeof(*psinfo), psinfo);

- fill_note(&notes[2], "CORE", NT_TASKSTRUCT, sizeof(*current), current);
+ fill_note(notes +2, "CORE", NT_TASKSTRUCT, sizeof(*current), current);

/* Try to dump the FPU. */
- if ((prstatus.pr_fpvalid = elf_core_copy_task_fpregs(current, &fpu)))
- fill_note(&notes[3], "CORE", NT_PRFPREG, sizeof(fpu), &fpu);
+ if ((prstatus->pr_fpvalid = elf_core_copy_task_fpregs(current, fpu)))
+ fill_note(notes +3, "CORE", NT_PRFPREG, sizeof(*fpu), fpu);
else
--numnote;
#ifdef ELF_CORE_COPY_XFPREGS
- if (elf_core_copy_task_xfpregs(current, &xfpu))
- fill_note(&notes[4], "LINUX", NT_PRXFPREG, sizeof(xfpu), &xfpu);
+ if (elf_core_copy_task_xfpregs(current, xfpu))
+ fill_note(notes +4, "LINUX", NT_PRXFPREG, sizeof(*xfpu), xfpu);
else
--numnote;
#else
- numnote --;
+ numnote--;
#endif

fs = get_fs();
set_fs(KERNEL_DS);

- DUMP_WRITE(&elf, sizeof(elf));
- offset += sizeof(elf); /* Elf header */
+ DUMP_WRITE(elf, sizeof(*elf));
+ offset += sizeof(*elf); /* Elf header */
offset += (segs+1) * sizeof(struct elf_phdr); /* Program headers */

/* Write notes phdr entry */
@@ -1276,8 +1297,8 @@
struct elf_phdr phdr;
int sz = 0;

- for(i = 0; i < numnote; i++)
- sz += notesize(&notes[i]);
+ for (i = 0; i < numnote; i++)
+ sz += notesize(notes + i);

sz += thread_status_size;

@@ -1290,7 +1311,7 @@
dataoff = offset = roundup(offset, ELF_EXEC_PAGESIZE);

/* Write program headers for segments dump */
- for(vma = current->mm->mmap; vma != NULL; vma = vma->vm_next) {
+ for (vma = current->mm->mmap; vma != NULL; vma = vma->vm_next) {
struct elf_phdr phdr;
size_t sz;

@@ -1312,8 +1333,8 @@
}

/* write out the notes section */
- for(i = 0; i < numnote; i++)
- if (!writenote(&notes[i], file))
+ for (i = 0; i < numnote; i++)
+ if (!writenote(notes + i, file))
goto end_coredump;

/* write out the thread status notes section */
@@ -1326,7 +1347,7 @@

DUMP_SEEK(dataoff);

- for(vma = current->mm->mmap; vma != NULL; vma = vma->vm_next) {
+ for (vma = current->mm->mmap; vma != NULL; vma = vma->vm_next) {
unsigned long addr;

if (!maydump(vma))
@@ -1373,7 +1394,14 @@
kfree(list_entry(tmp, struct elf_thread_status, list));
}

+ kfree(elf);
+ kfree(prstatus);
+ kfree(psinfo);
+ kfree(notes);
+ kfree(fpu);
+ kfree(xfpu);
return has_dumped;
+#undef NUM_NOTES
}

#endif /* USE_ELF_CORE_DUMP */
\
 
 \ /
  Last update: 2005-03-22 13:33    [W:0.029 / U:13.328 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site