linux-user: Use correct target SHMLBA in shmat()

The shmat() handling needs to do target-specific handling
of the attach address for shmat():
 * if the SHM_RND flag is passed, the address is rounded
   down to a SHMLBA boundary
 * if SHM_RND is not passed, then the call is failed EINVAL
   if the address is not a multiple of SHMLBA

Since SHMLBA is target-specific, we need to do this
checking and rounding in QEMU and can't leave it up to the
host syscall.

Allow targets to define TARGET_FORCE_SHMLBA and provide
a target_shmlba() function if appropriate, and update
do_shmat() to honour them.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Riku Voipio <riku.voipio@linaro.org>

1 files changed, 7 insertions, 0 deletions

diff --git a/linux-user/arm/target_syscall.h b/linux-user/arm/target_syscall.h
index cd021ff598..0879b4d4a8 100644
--- a/linux-user/arm/target_syscall.h
+++ b/linux-user/arm/target_syscall.h
@@ -33,4 +33,11 @@ struct target_pt_regs {
 #define TARGET_MLOCKALL_MCL_CURRENT 1
 #define TARGET_MLOCKALL_MCL_FUTURE  2
 
+#define TARGET_FORCE_SHMLBA
+
+static inline abi_ulong target_shmlba(CPUARMState *env)
+{
+    return 4 * 4096;
+}
+
 #endif /* ARM_TARGET_SYSCALL_H */