Date: Wed, 28 Jun 2017 05:28:16 +0000 (UTC) From: Alan Cox <alc@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-11@freebsd.org Subject: svn commit: r320438 - stable/11/sys/kern Message-ID: <201706280528.v5S5SGkP022196@repo.freebsd.org>
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Author: alc Date: Wed Jun 28 05:28:15 2017 New Revision: 320438 URL: https://svnweb.freebsd.org/changeset/base/320438 Log: MFC r315518 Avoid unnecessary calls to vm_map_protect() in elf_load_section(). 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(). Approved by: re (kib) Modified: stable/11/sys/kern/imgact_elf.c Directory Properties: stable/11/ (props changed) Modified: stable/11/sys/kern/imgact_elf.c ============================================================================== --- stable/11/sys/kern/imgact_elf.c Wed Jun 28 05:21:00 2017 (r320437) +++ stable/11/sys/kern/imgact_elf.c Wed Jun 28 05:28:15 2017 (r320438) @@ -596,7 +596,7 @@ __elfN(load_section)(struct image_params *imgp, vm_oof /* 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); } @@ -617,10 +617,12 @@ __elfN(load_section)(struct image_params *imgp, vm_oof } /* - * 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); }
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