accel/tcg: Add mips support to alloc_code_gen_buffer_splitwx_memfd

Re-use the 256MiB region handling from alloc_code_gen_buffer_anon,
and replace that with the shared file mapping.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

1 files changed, 38 insertions, 8 deletions

diff --git a/accel/tcg/translate-all.c b/accel/tcg/translate-all.c
index c37718db4d..02e1b05c42 100644
--- a/accel/tcg/translate-all.c
+++ b/accel/tcg/translate-all.c
@@ -1137,24 +1137,40 @@ static bool alloc_code_gen_buffer_anon(size_t size, int prot,
 
 static bool alloc_code_gen_buffer_splitwx_memfd(size_t size, Error **errp)
 {
-    void *buf_rw, *buf_rx;
+    void *buf_rw = NULL, *buf_rx = MAP_FAILED;
     int fd = -1;
 
+#ifdef __mips__
+    /* Find space for the RX mapping, vs the 256MiB regions. */
+    if (!alloc_code_gen_buffer_anon(size, PROT_NONE,
+                                    MAP_PRIVATE | MAP_ANONYMOUS |
+                                    MAP_NORESERVE, errp)) {
+        return false;
+    }
+    /* The size of the mapping may have been adjusted. */
+    size = tcg_ctx->code_gen_buffer_size;
+    buf_rx = tcg_ctx->code_gen_buffer;
+#endif
+
     buf_rw = qemu_memfd_alloc("tcg-jit", size, 0, &fd, errp);
     if (buf_rw == NULL) {
-        return false;
+        goto fail;
     }
 
+#ifdef __mips__
+    void *tmp = mmap(buf_rx, size, PROT_READ | PROT_EXEC,
+                     MAP_SHARED | MAP_FIXED, fd, 0);
+    if (tmp != buf_rx) {
+        goto fail_rx;
+    }
+#else
     buf_rx = mmap(NULL, size, PROT_READ | PROT_EXEC, MAP_SHARED, fd, 0);
     if (buf_rx == MAP_FAILED) {
-        error_setg_errno(errp, errno,
-                         "failed to map shared memory for execute");
-        munmap(buf_rw, size);
-        close(fd);
-        return false;
+        goto fail_rx;
     }
-    close(fd);
+#endif
 
+    close(fd);
     tcg_ctx->code_gen_buffer = buf_rw;
     tcg_ctx->code_gen_buffer_size = size;
     tcg_splitwx_diff = buf_rx - buf_rw;
@@ -1163,6 +1179,20 @@ static bool alloc_code_gen_buffer_splitwx_memfd(size_t size, Error **errp)
     qemu_madvise(buf_rw, size, QEMU_MADV_HUGEPAGE);
     qemu_madvise(buf_rx, size, QEMU_MADV_HUGEPAGE);
     return true;
+
+ fail_rx:
+    error_setg_errno(errp, errno, "failed to map shared memory for execute");
+ fail:
+    if (buf_rx != MAP_FAILED) {
+        munmap(buf_rx, size);
+    }
+    if (buf_rw) {
+        munmap(buf_rw, size);
+    }
+    if (fd >= 0) {
+        close(fd);
+    }
+    return false;
 }
 #endif /* CONFIG_POSIX */