[v2,29/30] accel/tcg/user-exec: Implement CPU-specific signal handler for loongarch64 hosts

Commit Message

WANG Xuerui Sept. 21, 2021, 8:19 p.m. UTC

Signed-off-by: WANG Xuerui <[e-mail]>
---
 accel/tcg/user-exec.c | 78 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 78 insertions(+)

Comments

Richard Henderson Sept. 22, 2021, 4:51 p.m. UTC | #1

On 9/21/21 1:19 PM, WANG Xuerui wrote:
> +        case 0b00011111110: /* stle.w */
> +        case 0b00011111111: /* stle.d */
> +            is_write = 1;
> +            break;
> +        default:
> +            /* test for am* instruction range */
> +            if (0b00011000000 <= sel && sel <= 0b00011100011) {
> +                is_write = 1;
> +            }

Probably better to fold the range check into the switch with

   case 0b00011000000 ... 0b00011100011:  /* am* insn range */

Otherwise,
Reviewed-by: Richard Henderson <[e-mail]>


r~

WANG Xuerui Sept. 22, 2021, 5:35 p.m. UTC | #2

Hi Richard,

On 9/23/21 00:51, Richard Henderson wrote:
> On 9/21/21 1:19 PM, WANG Xuerui wrote:
>> +        case 0b00011111110: /* stle.w */
>> +        case 0b00011111111: /* stle.d */
>> +            is_write = 1;
>> +            break;
>> +        default:
>> +            /* test for am* instruction range */
>> +            if (0b00011000000 <= sel && sel <= 0b00011100011) {
>> +                is_write = 1;
>> +            }
>
> Probably better to fold the range check into the switch with
>
>   case 0b00011000000 ... 0b00011100011:  /* am* insn range */

I just googled this particular syntax; it looks like a GCC-only 
extension, but is already used in a few places inside QEMU. So I think 
I'll take this advice and just make the range another switch arm.

Patch

diff --git a/accel/tcg/user-exec.c b/accel/tcg/user-exec.c
index 8fed542622..87660903b2 100644
--- a/accel/tcg/user-exec.c
+++ b/accel/tcg/user-exec.c
@@ -878,6 +878,84 @@  int cpu_signal_handler(int host_signum, void *pinfo,
     return handle_cpu_signal(pc, info, is_write, &uc->uc_sigmask);
 }
 
+#elif defined(__loongarch64)
+
+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.__pc;
+    uint32_t insn = *(uint32_t *)pc;
+    int is_write = 0;
+
+    /* Detect store by reading the instruction at the program counter.  */
+    switch ((insn >> 26) & 0b111111) {
+    case 0b001000: /* {ll,sc}.[wd] */
+        switch ((insn >> 24) & 0b11) {
+        case 0b01: /* sc.w */
+        case 0b11: /* sc.d */
+            is_write = 1;
+            break;
+        }
+        break;
+    case 0b001001: /* {ld,st}ox4.[wd] ({ld,st}ptr.[wd]) */
+        switch ((insn >> 24) & 0b11) {
+        case 0b01: /* stox4.w (stptr.w) */
+        case 0b11: /* stox4.d (stptr.d) */
+            is_write = 1;
+            break;
+        }
+        break;
+    case 0b001010: /* {ld,st}.* family */
+        switch ((insn >> 22) & 0b1111) {
+        case 0b0100: /* st.b */
+        case 0b0101: /* st.h */
+        case 0b0110: /* st.w */
+        case 0b0111: /* st.d */
+        case 0b1101: /* fst.s */
+        case 0b1111: /* fst.d */
+            is_write = 1;
+            break;
+        }
+        break;
+    case 0b001110: /* indexed, atomic, bounds-checking memory operations */
+        uint32_t sel = (insn >> 15) & 0b11111111111;
+
+        switch (sel) {
+        case 0b00000100000: /* stx.b */
+        case 0b00000101000: /* stx.h */
+        case 0b00000110000: /* stx.w */
+        case 0b00000111000: /* stx.d */
+        case 0b00001110000: /* fstx.s */
+        case 0b00001111000: /* fstx.d */
+        case 0b00011101100: /* fstgt.s */
+        case 0b00011101101: /* fstgt.d */
+        case 0b00011101110: /* fstle.s */
+        case 0b00011101111: /* fstle.d */
+        case 0b00011111000: /* stgt.b */
+        case 0b00011111001: /* stgt.h */
+        case 0b00011111010: /* stgt.w */
+        case 0b00011111011: /* stgt.d */
+        case 0b00011111100: /* stle.b */
+        case 0b00011111101: /* stle.h */
+        case 0b00011111110: /* stle.w */
+        case 0b00011111111: /* stle.d */
+            is_write = 1;
+            break;
+        default:
+            /* test for am* instruction range */
+            if (0b00011000000 <= sel && sel <= 0b00011100011) {
+                is_write = 1;
+            }
+            break;
+        }
+        break;
+    }
+
+    return handle_cpu_signal(pc, info, is_write, &uc->uc_sigmask);
+}
+
 #else
 
 #error host CPU specific signal handler needed