compiler-rt: sanitizer_common: use close_range() instead of looping #114442
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@llvm/pr-subscribers-compiler-rt-sanitizer Author: Kyle Evans (kevans91) Changes_SC_OPEN_MAX is quite high on FreeBSD, which makes this close() loop a quite obvious problem when attempting to do any kind of debugging in a process that uses StartSubprocess. Switch to using close_range(2) instead to close them all in a single syscall and dramatically reduce the runtime and syscall trace noise Linux has an equivalent syscall, but I do not have the capacity to test that it works there, so this is limited to SANITIZER_FREEBSD for the time being. Full diff: https://github.com/llvm/llvm-project/pull/114442.diff 3 Files Affected:
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_linux.cpp b/compiler-rt/lib/sanitizer_common/sanitizer_linux.cpp
index 33107eb0b42993..8b1850f85010cf 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_linux.cpp
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_linux.cpp
@@ -256,6 +256,11 @@ int internal_madvise(uptr addr, uptr length, int advice) {
return internal_syscall(SYSCALL(madvise), addr, length, advice);
}
+# if SANITIZER_FREEBSD
+uptr internal_close_range(fd_t lowfd, fd_t highfd, int flags) {
+ return internal_syscall(SYSCALL(close_range), lowfd, highfd, flags);
+}
+# endif
uptr internal_close(fd_t fd) { return internal_syscall(SYSCALL(close), fd); }
uptr internal_open(const char *filename, int flags) {
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_posix.h b/compiler-rt/lib/sanitizer_common/sanitizer_posix.h
index 1f0795caa420c7..b5491c540dc083 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_posix.h
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_posix.h
@@ -28,6 +28,9 @@ namespace __sanitizer {
// Don't use directly, use __sanitizer::OpenFile() instead.
uptr internal_open(const char *filename, int flags);
uptr internal_open(const char *filename, int flags, u32 mode);
+# if SANITIZER_FREEBSD
+uptr internal_close_range(fd_t lowfd, fd_t highfd, int flags);
+# endif
uptr internal_close(fd_t fd);
uptr internal_read(fd_t fd, void *buf, uptr count);
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_posix_libcdep.cpp b/compiler-rt/lib/sanitizer_common/sanitizer_posix_libcdep.cpp
index 7ee2319456d23e..894998090b01b3 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_posix_libcdep.cpp
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_posix_libcdep.cpp
@@ -543,7 +543,11 @@ pid_t StartSubprocess(const char *program, const char *const argv[],
internal_close(stderr_fd);
}
+# if SANITIZER_FREEBSD
+ internal_close_range(3, ~0U, 0);
+# else
for (int fd = sysconf(_SC_OPEN_MAX); fd > 2; fd--) internal_close(fd);
+# endif
internal_execve(program, const_cast<char **>(&argv[0]),
const_cast<char *const *>(envp));
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BTW, for future reference, I would recommend pressing the "re-request review" (the arrow circle) button after addressing feedback, to bring the PR back into the reviewers' "Review Requested" dashboards
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_SC_OPEN_MAX is quite high on FreeBSD, which makes this close() loop a quite obvious problem when attempting to do any kind of debugging in a process that uses StartSubprocess. Switch to using close_range(2) instead to close them all in a single syscall and dramatically reduce the runtime and syscall trace noise Linux has an equivalent syscall, but I do not have the capacity to test that it works there, so this is limited to SANITIZER_FREEBSD for the time being.
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…lvm#114442) _SC_OPEN_MAX is quite high on FreeBSD, which makes this close() loop a quite obvious problem when attempting to do any kind of debugging in a process that uses StartSubprocess. Switch to using close_range(2) instead to close them all in a single syscall and dramatically reduce the runtime and syscall trace noise Linux has an equivalent syscall, but I do not have the capacity to test that it works there, so this is limited to SANITIZER_FREEBSD for the time being.
…lvm#114442) _SC_OPEN_MAX is quite high on FreeBSD, which makes this close() loop a quite obvious problem when attempting to do any kind of debugging in a process that uses StartSubprocess. Switch to using close_range(2) instead to close them all in a single syscall and dramatically reduce the runtime and syscall trace noise Linux has an equivalent syscall, but I do not have the capacity to test that it works there, so this is limited to SANITIZER_FREEBSD for the time being.
_SC_OPEN_MAX is quite high on FreeBSD, which makes this close() loop a quite obvious problem when attempting to do any kind of debugging in a process that uses StartSubprocess. Switch to using close_range(2) instead to close them all in a single syscall and dramatically reduce the runtime and syscall trace noise
Linux has an equivalent syscall, but I do not have the capacity to test that it works there, so this is limited to SANITIZER_FREEBSD for the time being.