[PULL 3/6] linux-user: Adjust guest page protection for the host

[Laurent Vivier]

From: Richard Henderson <richard.henderson@linaro.org>

Executable guest pages are never directly executed by
the host, but do need to be readable for translation.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Message-Id: <20200519185645.3915-3-richard.henderson@linaro.org>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
---
 linux-user/mmap.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/linux-user/mmap.c b/linux-user/mmap.c
index 46c7eeba9bd2..f2615634201d 100644
--- a/linux-user/mmap.c
+++ b/linux-user/mmap.c
@@ -76,8 +76,12 @@ static int validate_prot_to_pageflags(int *host_prot, int 
prot)
      * don't bother transforming guest bit to host bit.  Any other
      * target-specific prot bits will not be understood by the host
      * and will need to be encoded into page_flags for qemu emulation.
+     *
+     * Pages that are executable by the guest will never be executed
+     * by the host, but the host will need to be able to read them.
      */
-    *host_prot = prot & (PROT_READ | PROT_WRITE | PROT_EXEC);
+    *host_prot = (prot & (PROT_READ | PROT_WRITE))
+               | (prot & PROT_EXEC ? PROT_READ : 0);
 
     return prot & ~valid ? 0 : page_flags;
 }
-- 
2.26.2