linux-kernel - Re: [PATCH 09/37] kgdb,blackfin: Add in kgdb_arch_set

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Message-ID: <4e5ebad50912301845p35b1ea98l2f91c2a209ee863a@mail.gmail.com>
Date:	Thu, 31 Dec 2009 10:45:43 +0800
From:	Sonic Zhang <sonic.adi@...il.com>
To:	"Zhang, Sonic" <Sonic.Zhang@...log.com>
Cc:	Mike Frysinger <vapier.adi@...il.com>,
	Jason Wessel <jason.wessel@...driver.com>,
	linux-kernel@...r.kernel.org, kgdb-bugreport@...ts.sourceforge.net,
	kdb@....sgi.com, mingo@...e.hu
Subject: Re: [PATCH 09/37] kgdb,blackfin: Add in kgdb_arch_set_pc for blackfin

I have to recall my last wrong patch.

In blackfin, kgdb is running in delayed exception IRQ5 other than in
exception IRQ3 directly.  Register reti other than retx in pt_regs is
the kgdb return address. So, don't put PC in gdb_regs into retx.

Sonic Zhang

Index: arch/blackfin/kernel/kgdb.c
============================
--- arch/blackfin/kernel/kgdb.c	(revision 8105)
+++ arch/blackfin/kernel/kgdb.c	(revision 8106)
@@ -147,7 +147,7 @@
 	regs->lb1 = gdb_regs[BFIN_LB1];
 	regs->usp = gdb_regs[BFIN_USP];
 	regs->syscfg = gdb_regs[BFIN_SYSCFG];
-	regs->retx = gdb_regs[BFIN_PC];
+	regs->retx = gdb_regs[BFIN_RETX];
 	regs->retn = gdb_regs[BFIN_RETN];
 	regs->rete = gdb_regs[BFIN_RETE];
 	regs->pc = gdb_regs[BFIN_PC];



On Mon, Dec 28, 2009 at 6:17 PM, Zhang, Sonic <Sonic.Zhang@...log.com> wrote:
> A little update.
>
> GDB uses field BFIN_PC as the resume address from debugging mode. But, field pc in struct pt_regs is where kernel resumes from an interrupt. So, BFIN_PC is actually retx when do kernel debugging.
>
>
> Sonic
>
>
> --- trunk/arch/blackfin/kernel/kgdb.c   2009-12-28 09:27:27 UTC (rev 8085)
> +++ trunk/arch/blackfin/kernel/kgdb.c   2009-12-28 10:08:30 UTC (rev 8086)
> @@ -79,7 +79,7 @@
>        gdb_regs[BFIN_RETX] = regs->retx;
>        gdb_regs[BFIN_RETN] = regs->retn;
>        gdb_regs[BFIN_RETE] = regs->rete;
> -       gdb_regs[BFIN_PC] = regs->pc;
> +       gdb_regs[BFIN_PC] = regs->retx;
>        gdb_regs[BFIN_CC] = 0;
>        gdb_regs[BFIN_EXTRA1] = 0;
>        gdb_regs[BFIN_EXTRA2] = 0;
> @@ -150,7 +150,7 @@
>        regs->retx = gdb_regs[BFIN_PC];
>        regs->retn = gdb_regs[BFIN_RETN];
>        regs->rete = gdb_regs[BFIN_RETE];
> -       regs->pc = gdb_regs[BFIN_PC];
> +       regs->pc = gdb_regs[BFIN_RETI];
>
>  #if 0                          /* can't change these */
>        regs->astat = gdb_regs[BFIN_ASTAT];
>
>
>
>
> -----Original Message-----
> From: Mike Frysinger [mailto:vapier.adi@...il.com]
> Sent: Sunday, December 27, 2009 5:12 AM
> To: Jason Wessel
> Cc: linux-kernel@...r.kernel.org; kgdb-bugreport@...ts.sourceforge.net; kdb@....sgi.com; mingo@...e.hu; Zhang, Sonic
> Subject: Re: [PATCH 09/37] kgdb,blackfin: Add in kgdb_arch_set_pc for blackfin
>
> On Wed, Dec 23, 2009 at 16:19, Jason Wessel wrote:
>> The new debug core api requires all architectures that use to debug
>> core to implement a function to set the program counter.
>>
>> CC: Mike Frysinger <vapier@...too.org>
>> Signed-off-by: Jason Wessel <jason.wessel@...driver.com>
>> ---
>>  arch/blackfin/kernel/kgdb.c |    5 +++++
>>  1 files changed, 5 insertions(+), 0 deletions(-)
>>
>> diff --git a/arch/blackfin/kernel/kgdb.c b/arch/blackfin/kernel/kgdb.c
>> index f1036b6..5965188 100644
>> --- a/arch/blackfin/kernel/kgdb.c
>> +++ b/arch/blackfin/kernel/kgdb.c
>> @@ -644,6 +644,11 @@ int kgdb_arch_remove_breakpoint(unsigned long
>> addr, char *bundle)
>>        return bfin_probe_kernel_write((char *)addr, bundle,
>> BREAK_INSTR_SIZE);
>>  }
>>
>> +void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long ip) {
>> +       regs->retx = ip;
>> +}
>> +
>>  int kgdb_arch_init(void)
>>  {
>>        kgdb_single_step = 0;
>
> Sonic should be able to check this.  our pc handling seems a little wonky atm:
>
> arch/blackfin/kernel/kgdb.c:
> void pt_regs_to_gdb_regs(unsigned long *gdb_regs, struct pt_regs *regs) { ...
>    gdb_regs[BFIN_RETI] = regs->pc;
>    gdb_regs[BFIN_RETX] = regs->retx;
>    gdb_regs[BFIN_PC] = regs->pc;
> ...
> }
> ...
> void gdb_regs_to_pt_regs(unsigned long *gdb_regs, struct pt_regs *regs) { ...
>    regs->pc = gdb_regs[BFIN_PC];
>    regs->retx = gdb_regs[BFIN_PC];
>    /* nothing for BFIN_RETI */
> ...
> }
> -mike
> --
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