[tip: core/rcu] tools/nolibc: Implement poll() based on ppoll()

["tip-bot2 for Willy Tarreau" <tip-bot2@linutronix.de>]

The following commit has been merged into the core/rcu branch of tip:

Commit-ID:     5b1c827ca3b349801e2faff4185118cfa74f94c6
Gitweb:        https://git.kernel.org/tip/5b1c827ca3b349801e2faff4185118cfa74f94c6
Author:        Willy Tarreau <w@1wt.eu>
AuthorDate:    Thu, 21 Jan 2021 08:20:27 +01:00
Committer:     Paul E. McKenney <paulmck@kernel.org>
CommitterDate: Thu, 21 Jan 2021 10:06:44 -08:00

tools/nolibc: Implement poll() based on ppoll()

Some architectures like arm64 do not implement poll() and have to use
ppoll() instead. This commit therefore makes poll() use ppoll() when
available. This is a port of nolibc's upstream commit 800f75c13ede to
the Linux kernel.

Fixes: 66b6f755ad45 ("rcutorture: Import a copy of nolibc")
Tested-by: Valentin Schneider <valentin.schneider@arm.com>
Tested-by: Mark Rutland <mark.rutland@arm.com> [arm64]
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
 tools/include/nolibc/nolibc.h | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/tools/include/nolibc/nolibc.h b/tools/include/nolibc/nolibc.h
index fdd5524..833693f 100644
--- a/tools/include/nolibc/nolibc.h
+++ b/tools/include/nolibc/nolibc.h
@@ -1652,7 +1652,17 @@ int sys_pivot_root(const char *new, const char *old)
 static __attribute__((unused))
 int sys_poll(struct pollfd *fds, int nfds, int timeout)
 {
+#if defined(__NR_ppoll)
+	struct timespec t;
+
+	if (timeout >= 0) {
+		t.tv_sec  = timeout / 1000;
+		t.tv_nsec = (timeout % 1000) * 1000000;
+	}
+	return my_syscall4(__NR_ppoll, fds, nfds, (timeout >= 0) ? &t : NULL, NULL);
+#else
 	return my_syscall3(__NR_poll, fds, nfds, timeout);
+#endif
 }
 
 static __attribute__((unused))