[PATCH v2 4/5] linux-user: Add x86_64 vsyscall page to /proc/self/maps

[Richard Henderson <richard.henderson@linaro.org>]

The page isn't (necessarily) present in the host /proc/self/maps,
and even if it might be it isn't present in page_flags, and even
if it was it might not have the same set of page permissions.

The easiest thing to do, particularly when it comes to the
"[vsyscall]" note at the end of line, is to special case it.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 linux-user/syscall.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 171c0caef3..eb867a5296 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -7005,6 +7005,15 @@ static int open_self_maps(void *cpu_env, int fd)
         }
     }
 
+#ifdef TARGET_X86_64
+    /*
+     * We only support execution from the vsyscall page.
+     * This is as if CONFIG_LEGACY_VSYSCALL_XONLY=y from v5.3.
+     */
+    dprintf(fd, "ffffffffff600000-ffffffffff601000 --xp 00000000 00:00 0"
+                "          [vsyscall]\n");
+#endif
+
     free(line);
     fclose(fp);
 
-- 
2.20.1