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Avoid unnecessary calls to vm_map_protect() in elf_load_section().

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Typically, when elf_load_section() unconditionally passed VM_PROT_ALL to
elf_map_insert(), it was needlessly enabling execute access on the
mapping, and it would later have to call vm_map_protect() to correct the
mapping's access rights.  Now, instead, elf_load_section() always passes
its parameter "prot" to elf_map_insert().  So, elf_load_section() must
only call vm_map_protect() if it needs to remove the write access that
was temporarily granted to perform a copyout().

Reviewed by:	kib
MFC after:	1 week
This commit is contained in:
alc 2017-03-18 23:37:00 +00:00
parent c059f37b9f
commit fb24921f88
1 changed files with 6 additions and 4 deletions
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10
sys/kern/imgact_elf.c
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@ -582,7 +582,7 @@ __elfN(load_section)(struct image_params *imgp, vm_ooffset_t offset,
/* This had damn well better be true! */
if (map_len != 0) {
rv = __elfN(map_insert)(imgp, map, NULL, 0, map_addr,
map_addr + map_len, VM_PROT_ALL, 0);
map_addr + map_len, prot, 0);
if (rv != KERN_SUCCESS)
return (EINVAL);
}
@ -603,10 +603,12 @@ __elfN(load_section)(struct image_params *imgp, vm_ooffset_t offset,
}
/*
* set it to the specified protection.
* Remove write access to the page if it was only granted by map_insert
* to allow copyout.
*/
vm_map_protect(map, trunc_page(map_addr), round_page(map_addr +
map_len), prot, FALSE);
if ((prot & VM_PROT_WRITE) == 0)
vm_map_protect(map, trunc_page(map_addr), round_page(map_addr +
map_len), prot, FALSE);
return (0);
}