[7.5] PATCH: PR backtrace/14646 [x32] backtrace doesn't work

[7.5] PATCH: PR backtrace/14646 [x32] backtrace doesn't work

[H.J. Lu]

Hi,

This patch backports the fix from trunk to 7.5 branch.  Tested on
Linux/x86-64 and Linux/x32.  OK to install?

Thanks.


H.J.
----
	PR backtrace/14646
	PR gdb/14647
	* i386-tdep.h (gdbarch_tdep): Remove sp_regnum_from_eax and
	pc_regnum_from_eax.
	* i386-tdep.c (i386_gdbarch_init): Don't use sp_regnum_from_eax
	nor pc_regnum_from_eax.
	* amd64-tdep.c (amd64_x32_init_abi): Don't set sp_regnum_from_eax
	nor pc_regnum_from_eax.

diff --git a/gdb/amd64-tdep.c b/gdb/amd64-tdep.c
index 5424926..8ae1142 100644
--- a/gdb/amd64-tdep.c
+++ b/gdb/amd64-tdep.c
@@ -2946,9 +2946,6 @@ amd64_x32_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
     tdesc = tdesc_x32;
   tdep->tdesc = tdesc;
 
-  tdep->sp_regnum_from_eax = AMD64_RSP_REGNUM;
-  tdep->pc_regnum_from_eax = AMD64_RIP_REGNUM;
-
   tdep->num_dword_regs = 17;
   set_tdesc_pseudo_register_type (gdbarch, amd64_x32_pseudo_register_type);
 
diff --git a/gdb/i386-tdep.c b/gdb/i386-tdep.c
index 84e9794..ddb20aa 100644
--- a/gdb/i386-tdep.c
+++ b/gdb/i386-tdep.c
@@ -7705,9 +7705,6 @@ i386_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
   tdep->num_mmx_regs = 8;
   tdep->num_ymm_regs = 0;
 
-  tdep->sp_regnum_from_eax = -1;
-  tdep->pc_regnum_from_eax = -1;
-
   tdesc_data = tdesc_data_alloc ();
 
   set_gdbarch_relocate_instruction (gdbarch, i386_relocate_instruction);
@@ -7752,14 +7749,6 @@ i386_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
       /* Support dword pseudo-register if it hasn't been disabled.  */
       tdep->eax_regnum = ymm0_regnum;
       ymm0_regnum += tdep->num_dword_regs;
-      if (tdep->sp_regnum_from_eax != -1)
-	set_gdbarch_sp_regnum (gdbarch,
-			       (tdep->eax_regnum
-				+ tdep->sp_regnum_from_eax));
-      if (tdep->pc_regnum_from_eax != -1)
-	set_gdbarch_pc_regnum (gdbarch,
-			       (tdep->eax_regnum
-				+ tdep->pc_regnum_from_eax));
     }
   else
     tdep->eax_regnum = -1;
diff --git a/gdb/i386-tdep.h b/gdb/i386-tdep.h
index 76afdce..5f233f5 100644
--- a/gdb/i386-tdep.h
+++ b/gdb/i386-tdep.h
@@ -149,14 +149,6 @@ struct gdbarch_tdep
      of pseudo dword register support.  */
   int eax_regnum;
 
-  /* Register number for SP, relative to %eax.  Set this to -1 to
-     indicate the absence of pseudo SP register support.  */
-  int sp_regnum_from_eax;
-
-  /* Register number for PC, relative to %eax.  Set this to -1 to
-     indicate the absence of pseudo PC register support.  */
-  int pc_regnum_from_eax;
-
   /* Number of core registers.  */
   int num_core_regs;
 

Re: [7.5] PATCH: PR backtrace/14646 [x32] backtrace doesn't work

[Joel Brobecker]

> This patch backports the fix from trunk to 7.5 branch.  Tested on
> Linux/x86-64 and Linux/x32.  OK to install?
[...]
> 	PR backtrace/14646
> 	PR gdb/14647
> 	* i386-tdep.h (gdbarch_tdep): Remove sp_regnum_from_eax and
> 	pc_regnum_from_eax.
> 	* i386-tdep.c (i386_gdbarch_init): Don't use sp_regnum_from_eax
> 	nor pc_regnum_from_eax.
> 	* amd64-tdep.c (amd64_x32_init_abi): Don't set sp_regnum_from_eax
> 	nor pc_regnum_from_eax.

I'm sorry to say that I am not comfortable at all with this going
in the 7.5 branch. If Mark is super confident, then OK, but this is
touching sp/pc handling for all x86 and x86-64 targets. And I don't
think that the issue this patch is fixing is that critical.

-- 
Joel

Re: [7.5] PATCH: PR backtrace/14646 [x32] backtrace doesn't work

[H.J. Lu]

On Sat, Oct 20, 2012 at 6:56 PM, Joel Brobecker <brobecker@adacore.com> wrote:
>> This patch backports the fix from trunk to 7.5 branch.  Tested on
>> Linux/x86-64 and Linux/x32.  OK to install?
> [...]
>>       PR backtrace/14646
>>       PR gdb/14647
>>       * i386-tdep.h (gdbarch_tdep): Remove sp_regnum_from_eax and
>>       pc_regnum_from_eax.
>>       * i386-tdep.c (i386_gdbarch_init): Don't use sp_regnum_from_eax
>>       nor pc_regnum_from_eax.
>>       * amd64-tdep.c (amd64_x32_init_abi): Don't set sp_regnum_from_eax
>>       nor pc_regnum_from_eax.
>
> I'm sorry to say that I am not comfortable at all with this going
> in the 7.5 branch. If Mark is super confident, then OK, but this is
> touching sp/pc handling for all x86 and x86-64 targets. And I don't
> think that the issue this patch is fixing is that critical.
>

This patch reverts the changed made on 7.5 branch, which
brings 7.5 branch back to 7.4 branch.  It should be 100% safe.

-- 
H.J.

Re: [7.5] PATCH: PR backtrace/14646 [x32] backtrace doesn't work

[Pedro Alves]

On 10/21/2012 02:56 AM, Joel Brobecker wrote:
>> This patch backports the fix from trunk to 7.5 branch.  Tested on
>> Linux/x86-64 and Linux/x32.  OK to install?
> [...]
>> 	PR backtrace/14646
>> 	PR gdb/14647
>> 	* i386-tdep.h (gdbarch_tdep): Remove sp_regnum_from_eax and
>> 	pc_regnum_from_eax.
>> 	* i386-tdep.c (i386_gdbarch_init): Don't use sp_regnum_from_eax
>> 	nor pc_regnum_from_eax.
>> 	* amd64-tdep.c (amd64_x32_init_abi): Don't set sp_regnum_from_eax
>> 	nor pc_regnum_from_eax.
> 
> I'm sorry to say that I am not comfortable at all with this going
> in the 7.5 branch. If Mark is super confident, then OK, but this is
> touching sp/pc handling for all x86 and x86-64 targets. And I don't
> think that the issue this patch is fixing is that critical.

I'm not Mark, but it looks safe on all x86 and x86-64 targets to me.
Note how tdep->sp_regnum_from_eax and tdep->sp_regnum_from_eax are -1
by default, and only x32 sets it to something else.  Then, the only use
for those fields:

-      if (tdep->sp_regnum_from_eax != -1)
-	set_gdbarch_sp_regnum (gdbarch,
-			       (tdep->eax_regnum
-				+ tdep->sp_regnum_from_eax));
-      if (tdep->pc_regnum_from_eax != -1)
-	set_gdbarch_pc_regnum (gdbarch,
-			       (tdep->eax_regnum
-				+ tdep->pc_regnum_from_eax));

only had effect on x32.

-- 
Pedro Alves

Re: [7.5] PATCH: PR backtrace/14646 [x32] backtrace doesn't work

[Mark Kettenis]

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> 
> On 10/21/2012 02:56 AM, Joel Brobecker wrote:
> >> This patch backports the fix from trunk to 7.5 branch.  Tested on
> >> Linux/x86-64 and Linux/x32.  OK to install?
> > [...]
> >> 	PR backtrace/14646
> >> 	PR gdb/14647
> >> 	* i386-tdep.h (gdbarch_tdep): Remove sp_regnum_from_eax and
> >> 	pc_regnum_from_eax.
> >> 	* i386-tdep.c (i386_gdbarch_init): Don't use sp_regnum_from_eax
> >> 	nor pc_regnum_from_eax.
> >> 	* amd64-tdep.c (amd64_x32_init_abi): Don't set sp_regnum_from_eax
> >> 	nor pc_regnum_from_eax.
> > 
> > I'm sorry to say that I am not comfortable at all with this going
> > in the 7.5 branch. If Mark is super confident, then OK, but this is
> > touching sp/pc handling for all x86 and x86-64 targets. And I don't
> > think that the issue this patch is fixing is that critical.
> 
> I'm not Mark, but it looks safe on all x86 and x86-64 targets to me.
> Note how tdep->sp_regnum_from_eax and tdep->sp_regnum_from_eax are -1
> by default, and only x32 sets it to something else.  Then, the only use
> for those fields:
> 
> -      if (tdep->sp_regnum_from_eax != -1)
> -	set_gdbarch_sp_regnum (gdbarch,
> -			       (tdep->eax_regnum
> -				+ tdep->sp_regnum_from_eax));
> -      if (tdep->pc_regnum_from_eax != -1)
> -	set_gdbarch_pc_regnum (gdbarch,
> -			       (tdep->eax_regnum
> -				+ tdep->pc_regnum_from_eax));
> 
> only had effect on x32.

Yeah, it's pretty safe.  Must say that I don't see the urgency as x32
is still in its infancy.

Re: [7.5] PATCH: PR backtrace/14646 [x32] backtrace doesn't work

[Joel Brobecker]

> > only had effect on x32.
> 
> Yeah, it's pretty safe.  Must say that I don't see the urgency as x32
> is still in its infancy.

Thanks, guys. This takes care of my concerns regarding this patch.

-- 
Joel

Re: [7.5] PATCH: PR backtrace/14646 [x32] backtrace doesn't work

[H.J. Lu]

On Fri, Nov 9, 2012 at 8:53 AM, Joel Brobecker <brobecker@adacore.com> wrote:
>> > only had effect on x32.
>>
>> Yeah, it's pretty safe.  Must say that I don't see the urgency as x32
>> is still in its infancy.
>
> Thanks, guys. This takes care of my concerns regarding this patch.
>
> --
> Joel

Fixed on 7.5 branch.

Thanks.

-- 
H.J.