[Qemu-devel] [PATCH 05/11] linux-user/sh4: Notice gUSA regions during signal delivery

[Richard Henderson <rth@twiddle.net>]

We translate gUSA regions atomically in a parallel context.
But in a serial context a gUSA region may be interrupted.
In that case, restart the region as the kernel would.

Signed-off-by: Richard Henderson <rth@twiddle.net>
---
 linux-user/signal.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/linux-user/signal.c b/linux-user/signal.c
index 3d18d1b..1e716a9 100644
--- a/linux-user/signal.c
+++ b/linux-user/signal.c
@@ -3471,6 +3471,23 @@ static abi_ulong get_sigframe(struct target_sigaction *ka,
     return (sp - frame_size) & -8ul;
 }
 
+/* Notice when we're in the middle of a gUSA region and reset.
+   Note that this will only occur for !parallel_cpus, as we will
+   translate such sequences differently in a parallel context.  */
+static void unwind_gusa(CPUSH4State *regs)
+{
+    /* If the stack pointer is sufficiently negative... */
+    if ((regs->gregs[15] & 0xc0000000u) == 0xc0000000u) {
+        /* Reset the PC to before the gUSA region, as computed from
+           R0 = region end, SP = -(region size), plus one more insn
+           that actually sets SP to the region size.  */
+        regs->pc = regs->gregs[0] + regs->gregs[15] - 2;
+
+        /* Reset the SP to the saved version in R1.  */
+        regs->gregs[15] = regs->gregs[1];
+    }
+}
+
 static void setup_sigcontext(struct target_sigcontext *sc,
                              CPUSH4State *regs, unsigned long mask)
 {
@@ -3534,6 +3551,8 @@ static void setup_frame(int sig, struct target_sigaction *ka,
     abi_ulong frame_addr;
     int i;
 
+    unwind_gusa(regs);
+
     frame_addr = get_sigframe(ka, regs->gregs[15], sizeof(*frame));
     trace_user_setup_frame(regs, frame_addr);
     if (!lock_user_struct(VERIFY_WRITE, frame, frame_addr, 0)) {
@@ -3583,6 +3602,8 @@ static void setup_rt_frame(int sig, struct target_sigaction *ka,
     abi_ulong frame_addr;
     int i;
 
+    unwind_gusa(regs);
+
     frame_addr = get_sigframe(ka, regs->gregs[15], sizeof(*frame));
     trace_user_setup_rt_frame(regs, frame_addr);
     if (!lock_user_struct(VERIFY_WRITE, frame, frame_addr, 0)) {
-- 
2.9.4