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From: Ilya Leoshkevich <iii@linux.ibm.com>
To: Cornelia Huck <cohuck@redhat.com>,
	Peter Maydell <peter.maydell@linaro.org>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Richard Henderson <richard.henderson@linaro.org>,
	Eduardo Habkost <ehabkost@redhat.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>,
	qemu-devel@nongnu.org, Ilya Leoshkevich <iii@linux.ibm.com>
Subject: [PATCH v2 1/2] target/i386: Make sure that vsyscall's tb->size != 0
Date: Wed, 19 May 2021 06:57:37 +0200	[thread overview]
Message-ID: <20210519045738.1335210-2-iii@linux.ibm.com> (raw)
In-Reply-To: <20210519045738.1335210-1-iii@linux.ibm.com>

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>
---
 target/i386/tcg/translate.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/target/i386/tcg/translate.c b/target/i386/tcg/translate.c
index 880bc45561..b5a2b981e2 100644
--- a/target/i386/tcg/translate.c
+++ b/target/i386/tcg/translate.c
@@ -8572,6 +8572,7 @@ 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
-- 
2.31.1



  reply	other threads:[~2021-05-19  4:59 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-19  4:57 [PATCH v2 0/2] target/i386: Make sure that vsyscall's tb->size != 0 Ilya Leoshkevich
2021-05-19  4:57 ` Ilya Leoshkevich [this message]
2021-05-19  4:57 ` [PATCH v2 2/2] tests/tcg/x86_64: add vsyscall smoke test Ilya Leoshkevich
2021-05-19 16:42   ` Richard Henderson
2021-05-19 11:14 ` [PATCH v2 0/2] target/i386: Make sure that vsyscall's tb->size != 0 Cornelia Huck
2021-05-19 17:13 ` Cornelia Huck

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