linux-user: fix O_NONBLOCK in signalfd4() and eventfd2() syscalls

On the hppa target userspace binaries may call signalfd4() and
eventfd2() with an old TARGET_O_NONBLOCK value of 000200004 instead of
000200000 for the "mask" syscall parameter, in which case the current
emulation doesn't handle the translation to the native O_NONBLOCK value
correctly.

The 0x04 bit is not masked out before the new O_NONBLOCK bit is set and
as such when calling the native syscall errors out with EINVAL.

Fix this by introducing TARGET_O_NONBLOCK_MASK which is used to mask off
all possible bits. This define defaults to TARGET_O_NONBLOCK when not
defined otherwise, so for all other targets the implementation will
behave as before.

This patch needs to be applied on top of my previous two patches.

Bug was found and patch was verified by using qemu-hppa as debian buildd
server on x86_64.

Signed-off-by: Helge Deller <deller@gmx.de>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>

Message-Id: <20210210061214.GA221322@ls3530.fritz.box>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>

linux-user/hppa/target_fcntl.h

@@ -9,6 +9,7 @@
 #define HPPA_TARGET_FCNTL_H
 
 #define TARGET_O_NONBLOCK    000200000
+#define TARGET_O_NONBLOCK_MASK 000200004 /* includes old HP-UX NDELAY flag */
 #define TARGET_O_APPEND      000000010
 #define TARGET_O_CREAT       000000400 /* not fcntl */
 #define TARGET_O_EXCL        000002000 /* not fcntl */

linux-user/syscall.c

@@ -277,6 +277,11 @@ static type name (type1 arg1,type2 arg2,type3 arg3,type4 arg4,type5 arg5,	\
 #define TARGET_NR__llseek TARGET_NR_llseek
 #endif
 
+/* some platforms need to mask more bits than just TARGET_O_NONBLOCK */
+#ifndef TARGET_O_NONBLOCK_MASK
+#define TARGET_O_NONBLOCK_MASK TARGET_O_NONBLOCK
+#endif
+
 #define __NR_sys_gettid __NR_gettid
 _syscall0(int, sys_gettid)
 
@@ -7777,7 +7782,7 @@ static abi_long do_signalfd4(int fd, abi_long mask, int flags)
     sigset_t host_mask;
     abi_long ret;
 
-    if (flags & ~(TARGET_O_NONBLOCK | TARGET_O_CLOEXEC)) {
+    if (flags & ~(TARGET_O_NONBLOCK_MASK | TARGET_O_CLOEXEC)) {
         return -TARGET_EINVAL;
     }
     if (!lock_user_struct(VERIFY_READ, target_mask, mask, 1)) {
@@ -12566,7 +12571,7 @@ static abi_long do_syscall1(void *cpu_env, int num, abi_long arg1,
 #if defined(TARGET_NR_eventfd2)
     case TARGET_NR_eventfd2:
     {
-        int host_flags = arg2 & (~(TARGET_O_NONBLOCK | TARGET_O_CLOEXEC));
+        int host_flags = arg2 & (~(TARGET_O_NONBLOCK_MASK | TARGET_O_CLOEXEC));
         if (arg2 & TARGET_O_NONBLOCK) {
             host_flags |= O_NONBLOCK;
         }