From: Ilya Leoshkevich <iii@linux.ibm.com>
Date: Wed, 19 May 2021 04:57:37 +0000 (+0200)
Subject: target/i386: Make sure that vsyscall's tb->size != 0
X-Git-Tag: v6.1.0-rc0~110^2~1
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=9b21049edd3c352efc615e030cd8e931e0c6f910;p=thirdparty%2Fqemu.git

target/i386: Make sure that vsyscall's tb->size != 0

tb_gen_code() assumes that tb->size must never be zero, otherwise it
may produce spurious exceptions. For x86_64 this may happen when
creating a translation block for the vsyscall page.

Fix by pretending that vsyscall translation blocks have at least one
instruction.

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20210519045738.1335210-2-iii@linux.ibm.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>
---

diff --git a/target/i386/tcg/translate.c b/target/i386/tcg/translate.c
index db56a483435..3ab8c238556 100644
--- a/target/i386/tcg/translate.c
+++ b/target/i386/tcg/translate.c
@@ -8583,6 +8583,7 @@ static void i386_tr_translate_insn(DisasContextBase *dcbase, CPUState *cpu)
      */
     if ((dc->base.pc_next & TARGET_PAGE_MASK) == TARGET_VSYSCALL_PAGE) {
         gen_exception(dc, EXCP_VSYSCALL, dc->base.pc_next);
+        dc->base.pc_next = dc->pc + 1;
         return;
     }
 #endif