Date: Fri, 28 Jul 2017 12:22:32 +0000 (UTC) From: Konstantin Belousov <kib@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r321652 - head/lib/libc/x86/sys Message-ID: <201707281222.v6SCMWdE057243@repo.freebsd.org>
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Author: kib Date: Fri Jul 28 12:22:32 2017 New Revision: 321652 URL: https://svnweb.freebsd.org/changeset/base/321652 Log: Simplify flow control. Also add explicit comment why libc cannot simply rely on open(2) failure in capability mode. Sponsored by: The FreeBSD Foundation MFC after: 1 week Modified: head/lib/libc/x86/sys/__vdso_gettc.c Modified: head/lib/libc/x86/sys/__vdso_gettc.c ============================================================================== --- head/lib/libc/x86/sys/__vdso_gettc.c Fri Jul 28 11:51:55 2017 (r321651) +++ head/lib/libc/x86/sys/__vdso_gettc.c Fri Jul 28 12:22:32 2017 (r321652) @@ -197,25 +197,24 @@ __vdso_init_hpet(uint32_t u) if (old_map != NULL) return; - if (cap_getmode(&mode) == 0 && mode != 0) - goto fail; + /* + * Explicitely check for the capability mode to avoid + * triggering trap_enocap on the device open by absolute path. + */ + if ((cap_getmode(&mode) == 0 && mode != 0) || + (fd = _open(devname, O_RDONLY)) == -1) { + /* Prevent the caller from re-entering. */ + atomic_cmpset_rel_ptr((volatile uintptr_t *)&hpet_dev_map[u], + (uintptr_t)old_map, (uintptr_t)MAP_FAILED); + return; + } - fd = _open(devname, O_RDONLY); - if (fd == -1) - goto fail; - new_map = mmap(NULL, PAGE_SIZE, PROT_READ, MAP_SHARED, fd, 0); _close(fd); if (atomic_cmpset_rel_ptr((volatile uintptr_t *)&hpet_dev_map[u], (uintptr_t)old_map, (uintptr_t)new_map) == 0 && new_map != MAP_FAILED) munmap((void *)new_map, PAGE_SIZE); - - return; -fail: - /* Prevent the caller from re-entering. */ - atomic_cmpset_rel_ptr((volatile uintptr_t *)&hpet_dev_map[u], - (uintptr_t)old_map, (uintptr_t)MAP_FAILED); } #ifdef WANT_HYPERV
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