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, 16 insertions, 0 deletions

diff --git a/linux-user/sparc/target_syscall.h b/linux-user/sparc/target_syscall.h
index 326f674..f97aa6b 100644
--- a/linux-user/sparc/target_syscall.h
+++ b/linux-user/sparc/target_syscall.h
@@ -22,4 +22,20 @@ struct target_pt_regs {
 #define TARGET_MLOCKALL_MCL_CURRENT 0x2000
 #define TARGET_MLOCKALL_MCL_FUTURE  0x4000
 
+/* For SPARC SHMLBA is determined at runtime in the kernel, and
+ * libc has to runtime-detect it using the hwcaps (see glibc
+ * sysdeps/unix/sysv/linux/sparc/getshmlba; we follow the same
+ * logic here, though we know we're not the sparc v9 64-bit case).
+ */
+#define TARGET_FORCE_SHMLBA
+
+static inline abi_ulong target_shmlba(CPUSPARCState *env)
+{
+    if (!(env->def->features & CPU_FEATURE_FLUSH)) {
+        return 64 * 1024;
+    } else {
+        return 256 * 1024;
+    }
+}
+
 #endif /* SPARC_TARGET_SYSCALL_H */