sys/linux, sys/freebsd: apply more ignore_return attributes

1. Apply ignore_return to semctl$GETVAL which produces random errno
values on linux and freebsd.

2. Apply ignore_return to prctl and remove the custom code in executor.

3. Remove the custom errno ignoring code in fuchsia executor.
The calls are already marked as ignore_return, so this is just a leftover.

4. Only reset errno for ignore_return.
The syscall can still return a resource (maybe).
We only need to reset errno for fallback coverage.

1 files changed, 1 insertions, 7 deletions

diff --git a/executor/executor_linux.h b/executor/executor_linux.h
index 8f0dc579a..8c5a19ef7 100644
--- a/executor/executor_linux.h
+++ b/executor/executor_linux.h
@@ -84,13 +84,7 @@ static intptr_t execute_syscall(const call_t* c, intptr_t a[kMaxArgs])
 {
 	if (c->call)
 		return c->call(a[0], a[1], a[2], a[3], a[4], a[5], a[6], a[7], a[8]);
-	intptr_t res = syscall(c->sys_nr, a[0], a[1], a[2], a[3], a[4], a[5]);
-	// Some prctl commands don't respect the normal convention for return values
-	// (e.g. PR_GET_TIMERSLACK, but there are more) and may produce all possible
-	// errno values. This conflicts with fallback coverage.
-	if (!flag_coverage && res == -1 && !strcmp(c->name, "prctl"))
-		errno = EINVAL;
-	return res;
+	return syscall(c->sys_nr, a[0], a[1], a[2], a[3], a[4], a[5]);
 }
 
 static void cover_open(cover_t* cov, bool extra)