[Qemu-riscv] [RFC v3 22/24] tcg: Add RISC-V cpu signal handler

[Alistair Francis]

Signed-off-by: Alistair Francis <address@hidden>
Signed-off-by: Michael Clark <address@hidden>
---
 accel/tcg/user-exec.c | 75 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 75 insertions(+)

diff --git a/accel/tcg/user-exec.c b/accel/tcg/user-exec.c
index cd75829cf2..941295ea49 100644
--- a/accel/tcg/user-exec.c
+++ b/accel/tcg/user-exec.c
@@ -571,6 +571,81 @@ int cpu_signal_handler(int host_signum, void *pinfo,
     return handle_cpu_signal(pc, info, is_write, &uc->uc_sigmask);
 }
 
+#elif defined(__riscv)
+
+int cpu_signal_handler(int host_signum, void *pinfo,
+                       void *puc)
+{
+    siginfo_t *info = pinfo;
+    ucontext_t *uc = puc;
+    greg_t pc = uc->uc_mcontext.__gregs[REG_PC];
+    uint32_t insn = *(uint32_t *)pc;
+    int is_write = 0;
+
+    /* Detect store by reading the instruction at the program
+       counter. Note: we currently only generate 32-bit
+       instructions so we thus only detect 32-bit stores */
+    switch (((insn >> 0) & 0b11)) {
+    case 3:
+        switch (((insn >> 2) & 0b11111)) {
+        case 8:
+            switch (((insn >> 12) & 0b111)) {
+            case 0: /* sb */
+            case 1: /* sh */
+            case 2: /* sw */
+            case 3: /* sd */
+            case 4: /* sq */
+                is_write = 1;
+                break;
+            default:
+                break;
+            }
+            break;
+        case 9:
+            switch (((insn >> 12) & 0b111)) {
+            case 2: /* fsw */
+            case 3: /* fsd */
+            case 4: /* fsq */
+                is_write = 1;
+                break;
+            default:
+                break;
+            }
+            break;
+        default:
+            break;
+        }
+    }
+
+    /* Check for compressed instructions */
+    switch (((insn >> 13) & 0b111)) {
+    case 7:
+        switch (insn & 0b11) {
+        case 0: /*c.sd */
+        case 2: /* c.sdsp */
+            is_write = 1;
+            break;
+        default:
+            break;
+        }
+        break;
+    case 6:
+        switch (insn & 0b11) {
+        case 0: /* c.sw */
+        case 3: /* c.swsp */
+            is_write = 1;
+            break;
+        default:
+            break;
+        }
+        break;
+    default:
+        break;
+    }
+
+    return handle_cpu_signal(pc, info, is_write, &uc->uc_sigmask);
+}
+
 #else
 
 #error host CPU specific signal handler needed
-- 
2.19.1