Do not handle protections on a case-by-case basis in the various alloc_code_gen_buffer instances; do it within a single loop in tcg_region_init.
Signed-off-by: Richard Henderson <richard.hender...@linaro.org> --- tcg/region.c | 40 +++++++++++++++++++++++++++++----------- 1 file changed, 29 insertions(+), 11 deletions(-) diff --git a/tcg/region.c b/tcg/region.c index 4dc1237ff4..fac416ebf5 100644 --- a/tcg/region.c +++ b/tcg/region.c @@ -530,11 +530,6 @@ static int alloc_code_gen_buffer(size_t tb_size, int splitwx, Error **errp) } #endif - if (qemu_mprotect_rwx(buf, size)) { - error_setg_errno(errp, errno, "mprotect of jit buffer"); - return false; - } - region.start_aligned = buf; region.total_size = size; @@ -818,8 +813,7 @@ void tcg_region_init(size_t tb_size, int splitwx, unsigned max_cpus) { const size_t page_size = qemu_real_host_page_size; size_t region_size; - size_t i; - int have_prot; + int have_prot, need_prot; /* Size the buffer. */ if (tb_size == 0) { @@ -875,14 +869,38 @@ void tcg_region_init(size_t tb_size, int splitwx, unsigned max_cpus) /* init the region struct */ qemu_mutex_init(®ion.lock); - /* Set guard pages. No need to do this for the rx_buf, only the rw_buf. */ - for (i = 0; i < region.n; i++) { + /* + * Set guard pages. No need to do this for the rx_buf, only the rw_buf. + * Work with the page protections set up with the initial mapping. + */ + need_prot = PAGE_READ | PAGE_WRITE; +#ifndef CONFIG_TCG_INTERPRETER + if (tcg_splitwx_diff == 0) { + need_prot |= PAGE_EXEC; + } +#endif + for (size_t i = 0, n = region.n; i < n; i++) { void *start, *end; int rc; tcg_region_bounds(i, &start, &end); - rc = qemu_mprotect_none(end, page_size); - g_assert(!rc); + if (have_prot != need_prot) { + if (need_prot == (PAGE_READ | PAGE_WRITE | PAGE_EXEC)) { + rc = qemu_mprotect_rwx(start, end - start); + } else if (need_prot == (PAGE_READ | PAGE_WRITE)) { + rc = qemu_mprotect_rw(start, end - start); + } else { + g_assert_not_reached(); + } + if (rc) { + error_setg_errno(&error_fatal, errno, + "mprotect of jit buffer"); + } + } + if (have_prot != 0) { + /* If guard-page permissions don't change, it isn't fatal. */ + (void)qemu_mprotect_none(end, page_size); + } } tcg_region_trees_init(); -- 2.25.1