From 9739e3767af19096898d63eb9f2f0ff5004797d2 Mon Sep 17 00:00:00 2001 From: Peter Maydell Date: Tue, 14 Aug 2018 17:17:19 +0100 Subject: [PATCH] accel/tcg: tb_gen_code(): Create single-insn TB for execution from non-RAM MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit If get_page_addr_code() returns -1, this indicates that there is no RAM page we can read a full TB from. Instead we must create a TB which contains a single instruction and which we do not cache, so it is executed only once. Since this means we can now have TBs which are not in any page list, we also need to make tb_phys_invalidate() handle them (by not trying to remove them from a nonexistent page list). Signed-off-by: Peter Maydell Reviewed-by: Richard Henderson Reviewed-by: Emilio G. Cota Tested-by: Cédric Le Goater Message-id: 20180710160013.26559-5-peter.maydell@linaro.org --- accel/tcg/translate-all.c | 19 ++++++++++++++++++- 1 file changed, 18 insertions(+), 1 deletion(-) diff --git a/accel/tcg/translate-all.c b/accel/tcg/translate-all.c index ff7d0145f4..898c3bb3d1 100644 --- a/accel/tcg/translate-all.c +++ b/accel/tcg/translate-all.c @@ -1493,7 +1493,7 @@ static void tb_phys_invalidate__locked(TranslationBlock *tb) */ void tb_phys_invalidate(TranslationBlock *tb, tb_page_addr_t page_addr) { - if (page_addr == -1) { + if (page_addr == -1 && tb->page_addr[0] != -1) { page_lock_tb(tb); do_tb_phys_invalidate(tb, true); page_unlock_tb(tb); @@ -1608,6 +1608,17 @@ tb_link_page(TranslationBlock *tb, tb_page_addr_t phys_pc, assert_memory_lock(); + if (phys_pc == -1) { + /* + * If the TB is not associated with a physical RAM page then + * it must be a temporary one-insn TB, and we have nothing to do + * except fill in the page_addr[] fields. + */ + assert(tb->cflags & CF_NOCACHE); + tb->page_addr[0] = tb->page_addr[1] = -1; + return tb; + } + /* * Add the TB to the page list, acquiring first the pages's locks. * We keep the locks held until after inserting the TB in the hash table, @@ -1677,6 +1688,12 @@ TranslationBlock *tb_gen_code(CPUState *cpu, phys_pc = get_page_addr_code(env, pc); + if (phys_pc == -1) { + /* Generate a temporary TB with 1 insn in it */ + cflags &= ~CF_COUNT_MASK; + cflags |= CF_NOCACHE | 1; + } + buffer_overflow: tb = tb_alloc(pc); if (unlikely(!tb)) {