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debug: enhance trap of mmap

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Don't install trap for mlockall case
Add another code path for -fPIE compilation,
in this case the address of mmap function is 'plt' address.
This commit is contained in:
Zdenek Kabelac 2014-09-18 16:56:13 +02:00
parent 34bdb83c52
commit d450c7fb10
1 changed files with 12 additions and 11 deletions
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17
lib/mm/memlock.c
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@ -346,10 +346,9 @@ static int _disable_mmap(void)
(void) mmap(NULL, -1, -1, -1, -1, -1);
plt = (unsigned char *)mmap;
if (plt[0] != 0xff || plt[1] != 0x25) {
log_error("Can't find jump entry for mmap remapping.");
_mmap_addr = NULL;
return 0;
}
log_debug("Can't find PLT jump entry assuming -fPIE linkage.");
_mmap_addr = plt;
} else {
#ifdef __x86_64__
abs_addr = plt + 6 + *(int32_t *)(plt + 2);
#endif /* __x86_64__ */
@ -357,10 +356,11 @@ static int _disable_mmap(void)
abs_addr = *(void **)(plt + 2);
#endif /* __i386__ */
_mmap_addr = *(void **)abs_addr;
}
if (mprotect((void *)((unsigned long)_mmap_addr & ~4095UL), 4096, PROT_READ|PROT_WRITE|PROT_EXEC)) {
log_sys_error("mprotect", "");
_mmap_addr = NULL;
return 1;
return 0;
}
_mmap_orig = *_mmap_addr;
}
@ -407,11 +407,12 @@ static void _lock_mem(struct cmd_context *cmd)
log_sys_error("open", _procselfmaps);
return;
}
if (!_disable_mmap())
stack;
}
log_very_verbose("Locking memory");
if (!_disable_mmap())
stack;
if (!_memlock_maps(cmd, LVM_MLOCK, &_mstats))
stack;
@ -433,8 +434,8 @@ static void _unlock_mem(struct cmd_context *cmd)
if (!_memlock_maps(cmd, LVM_MUNLOCK, &unlock_mstats))
stack;
_restore_mmap();
if (!_use_mlockall) {
_restore_mmap();
if (close(_maps_fd))
log_sys_error("close", _procselfmaps);
dm_free(_maps_buffer);