diff options
author | Richard Henderson <richard.henderson@linaro.org> | 2022-08-22 18:50:46 -0700 |
---|---|---|
committer | Richard Henderson <richard.henderson@linaro.org> | 2022-09-06 08:04:26 +0100 |
commit | 9867b30287ec98728e52ed49d03c666e86c90a04 (patch) | |
tree | 1ea34b38d5acc4e52d1d4e4c42714566cb97efd3 /accel/tcg/cpu-exec.c | |
parent | 7e0d9973ea665bf459b2dbd173d0e51bc6ca5216 (diff) |
accel/tcg: Document the faulting lookup in tb_lookup_cmp
It was non-obvious to me why we can raise an exception in
the middle of a comparison function, but it works.
While nearby, use TARGET_PAGE_ALIGN instead of open-coding.
Acked-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Diffstat (limited to 'accel/tcg/cpu-exec.c')
-rw-r--r-- | accel/tcg/cpu-exec.c | 11 |
1 files changed, 10 insertions, 1 deletions
diff --git a/accel/tcg/cpu-exec.c b/accel/tcg/cpu-exec.c index 7887af6f45..5f43b9769a 100644 --- a/accel/tcg/cpu-exec.c +++ b/accel/tcg/cpu-exec.c @@ -198,7 +198,16 @@ static bool tb_lookup_cmp(const void *p, const void *d) tb_page_addr_t phys_page2; target_ulong virt_page2; - virt_page2 = (desc->pc & TARGET_PAGE_MASK) + TARGET_PAGE_SIZE; + /* + * We know that the first page matched, and an otherwise valid TB + * encountered an incomplete instruction at the end of that page, + * therefore we know that generating a new TB from the current PC + * must also require reading from the next page -- even if the + * second pages do not match, and therefore the resulting insn + * is different for the new TB. Therefore any exception raised + * here by the faulting lookup is not premature. + */ + virt_page2 = TARGET_PAGE_ALIGN(desc->pc); phys_page2 = get_page_addr_code(desc->env, virt_page2); if (tb->page_addr[1] == phys_page2) { return true; |