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..5ec848b459f7 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(VERIFY_NONE, arg1, arg2, 0);
if (!a) {
return -TARGET_ENOMEM;
}