aboutsummaryrefslogtreecommitdiff
path: root/translate-all.c
diff options
context:
space:
mode:
authorRichard Henderson <rth@twiddle.net>2014-04-24 09:16:07 -0700
committerRichard Henderson <rth@twiddle.net>2014-05-24 08:45:00 -0700
commit483c76e14043a60926f7df4415d0e3749694158d (patch)
tree45878099a984a09a0ec596f0deda0c30671bc184 /translate-all.c
parent479eb12108b66265a8149b0fa90e16900bc217af (diff)
downloadqemu-arm-483c76e14043a60926f7df4415d0e3749694158d.tar.gz
tcg-mips: Constrain the code_gen_buffer to be within one 256mb segment
This assures us use of J for exit_tb and goto_tb, and JAL for calling into the generated bswap helpers. Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Richard Henderson <rth@twiddle.net>
Diffstat (limited to 'translate-all.c')
-rw-r--r--translate-all.c90
1 files changed, 85 insertions, 5 deletions
diff --git a/translate-all.c b/translate-all.c
index c631694a6e..6b7b46e761 100644
--- a/translate-all.c
+++ b/translate-all.c
@@ -513,14 +513,47 @@ static inline size_t size_code_gen_buffer(size_t tb_size)
return tb_size;
}
+#ifdef __mips__
+/* In order to use J and JAL within the code_gen_buffer, we require
+ that the buffer not cross a 256MB boundary. */
+static inline bool cross_256mb(void *addr, size_t size)
+{
+ return ((uintptr_t)addr ^ ((uintptr_t)addr + size)) & 0xf0000000;
+}
+
+/* We weren't able to allocate a buffer without crossing that boundary,
+ so make do with the larger portion of the buffer that doesn't cross.
+ Returns the new base of the buffer, and adjusts code_gen_buffer_size. */
+static inline void *split_cross_256mb(void *buf1, size_t size1)
+{
+ void *buf2 = (void *)(((uintptr_t)buf1 + size1) & 0xf0000000);
+ size_t size2 = buf1 + size1 - buf2;
+
+ size1 = buf2 - buf1;
+ if (size1 < size2) {
+ size1 = size2;
+ buf1 = buf2;
+ }
+
+ tcg_ctx.code_gen_buffer_size = size1;
+ return buf1;
+}
+#endif
+
#ifdef USE_STATIC_CODE_GEN_BUFFER
static uint8_t static_code_gen_buffer[DEFAULT_CODE_GEN_BUFFER_SIZE]
__attribute__((aligned(CODE_GEN_ALIGN)));
static inline void *alloc_code_gen_buffer(void)
{
- map_exec(static_code_gen_buffer, tcg_ctx.code_gen_buffer_size);
- return static_code_gen_buffer;
+ void *buf = static_code_gen_buffer;
+#ifdef __mips__
+ if (cross_256mb(buf, tcg_ctx.code_gen_buffer_size)) {
+ buf = split_cross_256mb(buf, tcg_ctx.code_gen_buffer_size);
+ }
+#endif
+ map_exec(buf, tcg_ctx.code_gen_buffer_size);
+ return buf;
}
#elif defined(USE_MMAP)
static inline void *alloc_code_gen_buffer(void)
@@ -562,16 +595,63 @@ static inline void *alloc_code_gen_buffer(void)
buf = mmap((void *)start, tcg_ctx.code_gen_buffer_size,
PROT_WRITE | PROT_READ | PROT_EXEC, flags, -1, 0);
- return buf == MAP_FAILED ? NULL : buf;
+ if (buf == MAP_FAILED) {
+ return NULL;
+ }
+
+#ifdef __mips__
+ if (cross_256mb(buf, tcg_ctx.code_gen_buffer_size)) {
+ /* Try again, with the original still mapped, to avoid re-aquiring
+ that 256mb crossing. This time don't specify an address. */
+ size_t size2, size1 = tcg_ctx.code_gen_buffer_size;
+ void *buf2 = mmap(NULL, size1, PROT_WRITE | PROT_READ | PROT_EXEC,
+ flags, -1, 0);
+ if (buf2 != MAP_FAILED) {
+ if (!cross_256mb(buf2, size1)) {
+ /* Success! Use the new buffer. */
+ munmap(buf, size1);
+ return buf2;
+ }
+ /* Failure. Work with what we had. */
+ munmap(buf2, size1);
+ }
+
+ /* Split the original buffer. Free the smaller half. */
+ buf2 = split_cross_256mb(buf, size1);
+ size2 = tcg_ctx.code_gen_buffer_size;
+ munmap(buf + (buf == buf2 ? size2 : 0), size1 - size2);
+ return buf2;
+ }
+#endif
+
+ return buf;
}
#else
static inline void *alloc_code_gen_buffer(void)
{
void *buf = g_malloc(tcg_ctx.code_gen_buffer_size);
- if (buf) {
- map_exec(buf, tcg_ctx.code_gen_buffer_size);
+ if (buf == NULL) {
+ return NULL;
}
+
+#ifdef __mips__
+ if (cross_256mb(buf, tcg_ctx.code_gen_buffer_size)) {
+ void *buf2 = g_malloc(tcg_ctx.code_gen_buffer_size);
+ if (buf2 != NULL && !cross_256mb(buf2, size1)) {
+ /* Success! Use the new buffer. */
+ free(buf);
+ buf = buf2;
+ } else {
+ /* Failure. Work with what we had. Since this is malloc
+ and not mmap, we can't free the other half. */
+ free(buf2);
+ buf = split_cross_256mb(buf, tcg_ctx.code_gen_buffer_size);
+ }
+ }
+#endif
+
+ map_exec(buf, tcg_ctx.code_gen_buffer_size);
return buf;
}
#endif /* USE_STATIC_CODE_GEN_BUFFER, USE_MMAP */