| Message ID | 1448282741-22897-2-git-send-email-rth@twiddle.net |
|---|---|
| State | New |
| Headers | show |
Am 23.11.2015 um 13:45 schrieb Richard Henderson: > From: John Clarke <johnc@kirriwa.net> > > A simple typo in the variable to use when comparing vs the highwater mark. > Reports are that qemu can in fact segfault occasionally due to this mistake. > > Signed-off-by: John Clarke <johnc@kirriwa.net> > Signed-off-by: Richard Henderson <rth@twiddle.net> > --- > tcg/tcg.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/tcg/tcg.c b/tcg/tcg.c > index 682af8a..b20ed19 100644 > --- a/tcg/tcg.c > +++ b/tcg/tcg.c > @@ -2443,7 +2443,7 @@ int tcg_gen_code(TCGContext *s, tcg_insn_unit *gen_code_buf) > one operation beginning below the high water mark cannot overrun > the buffer completely. Thus we can test for overflow after > generating code without having to check during generation. */ > - if (unlikely(s->code_gen_ptr > s->code_gen_highwater)) { > + if (unlikely((void *)s->code_ptr > s->code_gen_highwater)) { > return -1; > } > } > Is a comparison of void pointers portable? Or would it be better to cast both sides to uintptr_t? Or fix the declaration of code_gen_highwater to use an uint8_t pointer and cast s->code_ptr to that type? code_gen_highwater should be fixed anyway because in translate-all a difference is calculated with it. Stefan
On 11/23/2015 02:16 PM, Stefan Weil wrote: > Am 23.11.2015 um 13:45 schrieb Richard Henderson: >> From: John Clarke <johnc@kirriwa.net> >> >> A simple typo in the variable to use when comparing vs the highwater mark. >> Reports are that qemu can in fact segfault occasionally due to this mistake. >> >> Signed-off-by: John Clarke <johnc@kirriwa.net> >> Signed-off-by: Richard Henderson <rth@twiddle.net> >> --- >> tcg/tcg.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/tcg/tcg.c b/tcg/tcg.c >> index 682af8a..b20ed19 100644 >> --- a/tcg/tcg.c >> +++ b/tcg/tcg.c >> @@ -2443,7 +2443,7 @@ int tcg_gen_code(TCGContext *s, tcg_insn_unit *gen_code_buf) >> one operation beginning below the high water mark cannot overrun >> the buffer completely. Thus we can test for overflow after >> generating code without having to check during generation. */ >> - if (unlikely(s->code_gen_ptr > s->code_gen_highwater)) { >> + if (unlikely((void *)s->code_ptr > s->code_gen_highwater)) { >> return -1; >> } >> } >> > > Is a comparison of void pointers portable? Of course. Particularly since these really are pointers into the same allocated object. That's 100% ANSI C. > code_gen_highwater should be fixed anyway because > in translate-all a difference is calculated with it. Yes, but we freely make use of this gcc extension in many places. r~
diff --git a/tcg/tcg.c b/tcg/tcg.c index 682af8a..b20ed19 100644 --- a/tcg/tcg.c +++ b/tcg/tcg.c @@ -2443,7 +2443,7 @@ int tcg_gen_code(TCGContext *s, tcg_insn_unit *gen_code_buf) one operation beginning below the high water mark cannot overrun the buffer completely. Thus we can test for overflow after generating code without having to check during generation. */ - if (unlikely(s->code_gen_ptr > s->code_gen_highwater)) { + if (unlikely((void *)s->code_ptr > s->code_gen_highwater)) { return -1; } }