[PATCH] linux-user: Don't require PROT_READ for mincore

[PATCH] linux-user: Don't require PROT_READ for mincore

[Thomas Weißschuh]

The kernel does not require PROT_READ for addresses passed to mincore.
For example the fincore(1) tool from util-linux uses PROT_NONE and
currently does not work under qemu-user.

Example (with fincore(1) from util-linux 2.38):

$ fincore /proc/self/exe
RES PAGES  SIZE FILE
24K     6 22.1K /proc/self/exe

$ qemu-x86_64 /usr/bin/fincore /proc/self/exe
fincore: failed to do mincore: /proc/self/exe: Cannot allocate memory

With this patch:

$ ./build/qemu-x86_64 /usr/bin/fincore /proc/self/exe
RES PAGES  SIZE FILE
24K     6 22.1K /proc/self/exe

Signed-off-by: Thomas Weißschuh <thomas@t-8ch.de>
---
 linux-user/syscall.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 69f740ff98c8..0ebcbf3d7f90 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -11897,7 +11897,7 @@ static abi_long do_syscall1(CPUArchState *cpu_env, int num, abi_long arg1,
 #ifdef TARGET_NR_mincore
     case TARGET_NR_mincore:
         {
-            void *a = lock_user(VERIFY_READ, arg1, arg2, 0);
+            void *a = lock_user(0, arg1, arg2, 0);
             if (!a) {
                 return -TARGET_ENOMEM;
             }

base-commit: 7dbd6f8a27e30fe14adb3d5869097cddf24038d6
-- 
2.40.0