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[Qemu-devel] [PATCH] target/m68k: fix set_cc_op()

Laurent Vivier posted 1 patch 8 years, 1 month ago
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git fetch https://github.com/patchew-project/qemu tags/patchew/20171221142939.1339-1-laurent@vivier.eu
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There is a newer version of this series
target/m68k/cpu.h       | 2 +-
target/m68k/translate.c | 6 ++++++
2 files changed, 7 insertions(+), 1 deletion(-)
[Qemu-devel] [PATCH] target/m68k: fix set_cc_op()
Posted by Laurent Vivier 8 years, 1 month ago 
The first call of set_cc_op() in a new translation sequence
is done with old_op set to CC_OP_DYNAMIC (-1).

This will do an out of bound access to the array cc_op_live[].

We fix that by adding an entry in cc_op_live[] for CC_OP_DYNAMIC,
and in this case we can also discard QREG_CC_OP.

Reported-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
---
 target/m68k/cpu.h       | 2 +-
 target/m68k/translate.c | 6 ++++++
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/target/m68k/cpu.h b/target/m68k/cpu.h
index afae5f68ac..5d03764eab 100644
--- a/target/m68k/cpu.h
+++ b/target/m68k/cpu.h
@@ -182,7 +182,7 @@ void cpu_m68k_set_fpcr(CPUM68KState *env, uint32_t val);
  */
 typedef enum {
     /* Translator only -- use env->cc_op.  */
-    CC_OP_DYNAMIC = -1,
+    CC_OP_DYNAMIC,
 
     /* Each flag bit computed into cc_[xcnvz].  */
     CC_OP_FLAGS,
diff --git a/target/m68k/translate.c b/target/m68k/translate.c
index b60909222c..61ac1a8e83 100644
--- a/target/m68k/translate.c
+++ b/target/m68k/translate.c
@@ -207,6 +207,7 @@ typedef void (*disas_proc)(CPUM68KState *env, DisasContext *s, uint16_t insn);
 #endif
 
 static const uint8_t cc_op_live[CC_OP_NB] = {
+    [CC_OP_DYNAMIC] = CCF_C | CCF_V | CCF_Z | CCF_N | CCF_X,
     [CC_OP_FLAGS] = CCF_C | CCF_V | CCF_Z | CCF_N | CCF_X,
     [CC_OP_ADDB ... CC_OP_ADDL] = CCF_X | CCF_N | CCF_V,
     [CC_OP_SUBB ... CC_OP_SUBL] = CCF_X | CCF_N | CCF_V,
@@ -237,6 +238,11 @@ static void set_cc_op(DisasContext *s, CCOp op)
     if (dead & CCF_V) {
         tcg_gen_discard_i32(QREG_CC_V);
     }
+
+    /* Discard any computed CC_OP value */
+    if (old_op == CC_OP_DYNAMIC) {
+        tcg_gen_discard_i32(QREG_CC_OP);
+    }
 }
 
 /* Update the CPU env CC_OP state.  */
-- 
2.14.3
Re: [Qemu-devel] [PATCH] target/m68k: fix set_cc_op()
Posted by Paolo Bonzini 8 years, 1 month ago 
On 21/12/2017 15:29, Laurent Vivier wrote:
> The first call of set_cc_op() in a new translation sequence
> is done with old_op set to CC_OP_DYNAMIC (-1).
> 
> This will do an out of bound access to the array cc_op_live[].
> 
> We fix that by adding an entry in cc_op_live[] for CC_OP_DYNAMIC,
> and in this case we can also discard QREG_CC_OP.
> 
> Reported-by: Thomas Huth <thuth@redhat.com>
> Signed-off-by: Laurent Vivier <laurent@vivier.eu>
> ---
>  target/m68k/cpu.h       | 2 +-
>  target/m68k/translate.c | 6 ++++++
>  2 files changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/target/m68k/cpu.h b/target/m68k/cpu.h
> index afae5f68ac..5d03764eab 100644
> --- a/target/m68k/cpu.h
> +++ b/target/m68k/cpu.h
> @@ -182,7 +182,7 @@ void cpu_m68k_set_fpcr(CPUM68KState *env, uint32_t val);
>   */
>  typedef enum {
>      /* Translator only -- use env->cc_op.  */
> -    CC_OP_DYNAMIC = -1,
> +    CC_OP_DYNAMIC,
>  
>      /* Each flag bit computed into cc_[xcnvz].  */
>      CC_OP_FLAGS,
> diff --git a/target/m68k/translate.c b/target/m68k/translate.c
> index b60909222c..61ac1a8e83 100644
> --- a/target/m68k/translate.c
> +++ b/target/m68k/translate.c
> @@ -207,6 +207,7 @@ typedef void (*disas_proc)(CPUM68KState *env, DisasContext *s, uint16_t insn);
>  #endif
>  
>  static const uint8_t cc_op_live[CC_OP_NB] = {
> +    [CC_OP_DYNAMIC] = CCF_C | CCF_V | CCF_Z | CCF_N | CCF_X,
>      [CC_OP_FLAGS] = CCF_C | CCF_V | CCF_Z | CCF_N | CCF_X,
>      [CC_OP_ADDB ... CC_OP_ADDL] = CCF_X | CCF_N | CCF_V,
>      [CC_OP_SUBB ... CC_OP_SUBL] = CCF_X | CCF_N | CCF_V,
> @@ -237,6 +238,11 @@ static void set_cc_op(DisasContext *s, CCOp op)
>      if (dead & CCF_V) {
>          tcg_gen_discard_i32(QREG_CC_V);
>      }
> +
> +    /* Discard any computed CC_OP value */
> +    if (old_op == CC_OP_DYNAMIC) {
> +        tcg_gen_discard_i32(QREG_CC_OP);
> +    }
>  }
>  
>  /* Update the CPU env CC_OP state.  */
> 

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Re: [Qemu-devel] [PATCH] target/m68k: fix set_cc_op()
Posted by Richard Henderson 8 years, 1 month ago 
On 12/21/2017 06:29 AM, Laurent Vivier wrote:
> The first call of set_cc_op() in a new translation sequence
> is done with old_op set to CC_OP_DYNAMIC (-1).
> 
> This will do an out of bound access to the array cc_op_live[].
> 
> We fix that by adding an entry in cc_op_live[] for CC_OP_DYNAMIC,
> and in this case we can also discard QREG_CC_OP.
> 
> Reported-by: Thomas Huth <thuth@redhat.com>
> Signed-off-by: Laurent Vivier <laurent@vivier.eu>
> ---
>  target/m68k/cpu.h       | 2 +-
>  target/m68k/translate.c | 6 ++++++
>  2 files changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/target/m68k/cpu.h b/target/m68k/cpu.h
> index afae5f68ac..5d03764eab 100644
> --- a/target/m68k/cpu.h
> +++ b/target/m68k/cpu.h
> @@ -182,7 +182,7 @@ void cpu_m68k_set_fpcr(CPUM68KState *env, uint32_t val);
>   */
>  typedef enum {
>      /* Translator only -- use env->cc_op.  */
> -    CC_OP_DYNAMIC = -1,
> +    CC_OP_DYNAMIC,
>  
>      /* Each flag bit computed into cc_[xcnvz].  */
>      CC_OP_FLAGS,
> diff --git a/target/m68k/translate.c b/target/m68k/translate.c
> index b60909222c..61ac1a8e83 100644
> --- a/target/m68k/translate.c
> +++ b/target/m68k/translate.c
> @@ -207,6 +207,7 @@ typedef void (*disas_proc)(CPUM68KState *env, DisasContext *s, uint16_t insn);
>  #endif
>  
>  static const uint8_t cc_op_live[CC_OP_NB] = {
> +    [CC_OP_DYNAMIC] = CCF_C | CCF_V | CCF_Z | CCF_N | CCF_X,
>      [CC_OP_FLAGS] = CCF_C | CCF_V | CCF_Z | CCF_N | CCF_X,
>      [CC_OP_ADDB ... CC_OP_ADDL] = CCF_X | CCF_N | CCF_V,
>      [CC_OP_SUBB ... CC_OP_SUBL] = CCF_X | CCF_N | CCF_V,

These bits are fine.

> @@ -237,6 +238,11 @@ static void set_cc_op(DisasContext *s, CCOp op)
>      if (dead & CCF_V) {
>          tcg_gen_discard_i32(QREG_CC_V);
>      }
> +
> +    /* Discard any computed CC_OP value */
> +    if (old_op == CC_OP_DYNAMIC) {
> +        tcg_gen_discard_i32(QREG_CC_OP);
> +    }

This doesn't help, since the previous setting of CC_OP is certain to be in a
different TB and therefore there is no code within the current TB to discard.


r~
Re: [Qemu-devel] [PATCH] target/m68k: fix set_cc_op()
Posted by Laurent Vivier 8 years, 1 month ago 
Le 21/12/2017 à 16:58, Richard Henderson a écrit :
> On 12/21/2017 06:29 AM, Laurent Vivier wrote:
>> The first call of set_cc_op() in a new translation sequence
>> is done with old_op set to CC_OP_DYNAMIC (-1).
>>
>> This will do an out of bound access to the array cc_op_live[].
>>
>> We fix that by adding an entry in cc_op_live[] for CC_OP_DYNAMIC,
>> and in this case we can also discard QREG_CC_OP.
>>
>> Reported-by: Thomas Huth <thuth@redhat.com>
>> Signed-off-by: Laurent Vivier <laurent@vivier.eu>
>> ---
>>  target/m68k/cpu.h       | 2 +-
>>  target/m68k/translate.c | 6 ++++++
>>  2 files changed, 7 insertions(+), 1 deletion(-)
>>
>> diff --git a/target/m68k/cpu.h b/target/m68k/cpu.h
>> index afae5f68ac..5d03764eab 100644
>> --- a/target/m68k/cpu.h
>> +++ b/target/m68k/cpu.h
>> @@ -182,7 +182,7 @@ void cpu_m68k_set_fpcr(CPUM68KState *env, uint32_t val);
>>   */
>>  typedef enum {
>>      /* Translator only -- use env->cc_op.  */
>> -    CC_OP_DYNAMIC = -1,
>> +    CC_OP_DYNAMIC,
>>  
>>      /* Each flag bit computed into cc_[xcnvz].  */
>>      CC_OP_FLAGS,
>> diff --git a/target/m68k/translate.c b/target/m68k/translate.c
>> index b60909222c..61ac1a8e83 100644
>> --- a/target/m68k/translate.c
>> +++ b/target/m68k/translate.c
>> @@ -207,6 +207,7 @@ typedef void (*disas_proc)(CPUM68KState *env, DisasContext *s, uint16_t insn);
>>  #endif
>>  
>>  static const uint8_t cc_op_live[CC_OP_NB] = {
>> +    [CC_OP_DYNAMIC] = CCF_C | CCF_V | CCF_Z | CCF_N | CCF_X,
>>      [CC_OP_FLAGS] = CCF_C | CCF_V | CCF_Z | CCF_N | CCF_X,
>>      [CC_OP_ADDB ... CC_OP_ADDL] = CCF_X | CCF_N | CCF_V,
>>      [CC_OP_SUBB ... CC_OP_SUBL] = CCF_X | CCF_N | CCF_V,
> 
> These bits are fine.
> 
>> @@ -237,6 +238,11 @@ static void set_cc_op(DisasContext *s, CCOp op)
>>      if (dead & CCF_V) {
>>          tcg_gen_discard_i32(QREG_CC_V);
>>      }
>> +
>> +    /* Discard any computed CC_OP value */
>> +    if (old_op == CC_OP_DYNAMIC) {
>> +        tcg_gen_discard_i32(QREG_CC_OP);
>> +    }
> 
> This doesn't help, since the previous setting of CC_OP is certain to be in a
> different TB and therefore there is no code within the current TB to discard.

OK, I remove this.

Thanks,
Laurent

Patchew 2.1-devel-b67e4c2

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