On Sat, Mar 20, 2021 at 10:57:19AM -0600, Richard Henderson wrote: > The rw portion of the buffer is the only one in which overruns > can be generated. Allow the rx portion to be more completely > covered by huge pages. > > Signed-off-by: Richard Henderson <richard.hender...@linaro.org> > --- > tcg/tcg.c | 12 +++++------- > 1 file changed, 5 insertions(+), 7 deletions(-) > > diff --git a/tcg/tcg.c b/tcg/tcg.c > index de91bb6e9e..88c9e6f8a4 100644 > --- a/tcg/tcg.c > +++ b/tcg/tcg.c > @@ -828,7 +828,6 @@ void tcg_region_init(void) > size_t region_size; > size_t n_regions; > size_t i; > - uintptr_t splitwx_diff; > > n_regions = tcg_n_regions(); > > @@ -858,8 +857,11 @@ void tcg_region_init(void) > /* account for that last guard page */ > region.end -= page_size; > > - /* set guard pages */ > - splitwx_diff = tcg_splitwx_diff; > + /* > + * Set guard pages in the rw buffer, as that's the one into which > + * buffer overruns could occur. Do not set guard pages in the rx > + * buffer -- let that one use hugepages throughout. > + */ > for (i = 0; i < region.n; i++) { > void *start, *end; > int rc; > @@ -867,10 +869,6 @@ void tcg_region_init(void) > tcg_region_bounds(i, &start, &end); > rc = qemu_mprotect_none(end, page_size); > g_assert(!rc); > - if (splitwx_diff) { > - rc = qemu_mprotect_none(end + splitwx_diff, page_size); > - g_assert(!rc); > - } > } > > tcg_region_trees_init(); > -- > 2.25.1 >
Thanks for fixing the issue, Richard, I have two questions: - Should we keep guards pages for rx on all platforms except darwin? (that would make it similar to what Philippe proposed in the comments to patch 2). - What does mean that rx might be covered by huge pages? (perhaps I'm missing some context) Otherwise, Reviewed-by: Roman Bolshakov <r.bolsha...@yadro.com> Tested-by: Roman Bolshakov <r.bolsha...@yadro.com> BR, Roman