Re: [PATCH 1/2] target/i386: Make sure that vsyscall's tb->size != 0

[Richard Henderson]

On 5/11/21 11:02 PM, Ilya Leoshkevich wrote:

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


Reviewed-by: Richard Henderson 

r~

[PATCH 1/2] target/i386: Make sure that vsyscall's tb->size != 0

[Ilya Leoshkevich]

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 
---
 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
-- 
2.29.2