linux-user: Add strace support for printing arguments of syscalls used to lock and unlock memory
This patch implements strace argument printing functionality for following syscalls:
* mlock, munlock, mlockall, munlockall - lock and unlock memory
int mlock(const void *addr, size_t len)
int munlock(const void *addr, size_t len)
int mlockall(int flags)
int munlockall(void)
man page: https://man7.org/linux/man-pages/man2/mlock.2.html
Implementation notes:
Syscall mlockall() takes an argument that is composed of predefined values
which represent flags that determine the type of locking operation that is
to be performed. For that reason, a printing function "print_mlockall" was
stated in file "strace.list". This printing function uses an already existing
function "print_flags()" to print the "flags" argument. These flags are stated
inside an array "mlockall_flags" that contains values of type "struct flags".
These values are instantiated using an existing macro "FLAG_TARGET()" that
crates aproppriate target flag values based on those defined in files
'/target_syscall.h'. These target flag values were changed from
"TARGET_MLOCKALL_MCL*" to "TARGET_MCL_*" so that they can be aproppriately set
and recognised in "strace.c" with "FLAG_TARGET()". Value for "MCL_ONFAULT"
was added in this patch. This value was also added in "syscall.c" in function
"target_to_host_mlockall_arg()". Because this flag value was added in kernel
version 4.4, it is enwrapped in an #ifdef directive (both in "syscall.c" and
in "strace.c") as to support older kernel versions.
The other syscalls have only primitive argument types, so the
rest of the implementation was handled by stating an appropriate
printing format in file "strace.list". Syscall mlock2() is not implemented in
"syscall.c" and thus it's argument printing is not implemented in this patch.
Signed-off-by: Filip Bozuta <Filip.Bozuta@syrmia.com>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Message-Id: <20200811164553.27713-4-Filip.Bozuta@syrmia.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index ec71921..027dea3 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -6975,12 +6975,18 @@
{
int result = 0;
- if (arg & TARGET_MLOCKALL_MCL_CURRENT) {
+ if (arg & TARGET_MCL_CURRENT) {
result |= MCL_CURRENT;
}
- if (arg & TARGET_MLOCKALL_MCL_FUTURE) {
+ if (arg & TARGET_MCL_FUTURE) {
result |= MCL_FUTURE;
}
+#ifdef MCL_ONFAULT
+ if (arg & TARGET_MCL_ONFAULT) {
+ result |= MCL_ONFAULT;
+ }
+#endif
+
return result;
}
#endif
