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[Qemu-devel] [PATCH] linux-user: elfload: allocate and initialize memsz-
From: |
Max Filippov |
Subject: |
[Qemu-devel] [PATCH] linux-user: elfload: allocate and initialize memsz-filesz gap |
Date: |
Sun, 12 Jul 2009 15:02:38 +0400 |
User-agent: |
KMail/1.11.4 (Linux/2.6.29.5-191.fc11.x86_64; KDE/4.2.4; x86_64; ; ) |
Hello.
I'm having ppc ELF binaries that I'm running on x86 in linux-user emulation.
Some of these binaries work fine, but others segfault.
The latter binaries have segments with p_filesz < p_memsz and sections like
.bss in this gap.
Segfaults usually happen in attempt to access address within this gap.
According to the linux-user/elfload.c only first p_filesz bytes of such
segments are mmaped and mprotected.
This patch mmaps p_memsz bytes and then zero out last p_memsz - p_filesz bytes
of such segments.
Is there a better way to do it?
Signed-off-by: Max Filippov <address@hidden>
---
diff -burN qemu-snapshot-2009-07-11_r7249-orig/linux-user/elfload.c
qemu-snapshot-2009-07-11_r7249/linux-user/elfload.c
--- qemu-snapshot-2009-07-11_r7249-orig/linux-user/elfload.c 2009-07-11
06:12:23.000000000 +0400
+++ qemu-snapshot-2009-07-11_r7249/linux-user/elfload.c 2009-07-12
04:47:47.000000000 +0400
@@ -1380,7 +1380,7 @@
}
error = target_mmap(TARGET_ELF_PAGESTART(load_bias +
elf_ppnt->p_vaddr),
- (elf_ppnt->p_filesz +
+ (elf_ppnt->p_memsz +
TARGET_ELF_PAGEOFFSET(elf_ppnt->p_vaddr)),
elf_prot,
(MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE),
@@ -1392,6 +1392,20 @@
exit(-1);
}
+ if(elf_ppnt->p_memsz > elf_ppnt->p_filesz) {
+ abi_ulong pg = TARGET_ELF_PAGESTART(load_bias + elf_ppnt->p_vaddr)
+
+ (elf_ppnt->p_filesz +
+ TARGET_ELF_PAGEOFFSET(elf_ppnt->p_vaddr));
+ abi_ulong sz = elf_ppnt->p_memsz - elf_ppnt->p_filesz;
+
+ void *p = lock_user(PAGE_READ | PAGE_WRITE, pg, sz, 0);
+
+ if (p) {
+ memset(p, 0, sz);
+ unlock_user(p, pg, sz);
+ }
+ }
+
#ifdef LOW_ELF_STACK
if (TARGET_ELF_PAGESTART(elf_ppnt->p_vaddr) < elf_stack)
elf_stack = TARGET_ELF_PAGESTART(elf_ppnt->p_vaddr);
Thanks.
-- Max
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