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Thu, 08 Mar 2018 08:41:59 -0800 (PST) MIME-Version: 1.0 Received: by 10.31.254.65 with HTTP; Thu, 8 Mar 2018 08:41:59 -0800 (PST) In-Reply-To: <382abcdd-5264-0c0c-282f-d1f52ecff8e3@linaro.org> References: <20180305234309.233226-1-dianders@chromium.org> <382abcdd-5264-0c0c-282f-d1f52ecff8e3@linaro.org> From: Doug Anderson Date: Thu, 8 Mar 2018 08:41:59 -0800 X-Google-Sender-Auth: SLORXc4tvcBvG-kReuCATlW0wK0 Message-ID: Subject: Re: [PATCH v2] arm64/debug: Fix registers on sleeping tasks To: Daniel Thompson X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20180308_084219_964800_17954EE9 X-CRM114-Status: GOOD ( 17.97 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , Catalin Marinas , Brian Norris , Will Deacon , LKML , evgreen@chromium.org, swboyd@chromium.org, Linux ARM Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP Hi, On Thu, Mar 8, 2018 at 8:19 AM, Daniel Thompson wrote: > On 05/03/18 23:43, Douglas Anderson wrote: >> >> This is the equivalent of commit 001bf455d206 ("ARM: 8428/1: kgdb: Fix >> registers on sleeping tasks") but for arm64. Nuff said. >> >> ...well, perhaps I could also add that task_pt_regs are userspace >> registers and that's not what kgdb is supposed to be reporting. We're >> supposed to be reporting kernel registers. >> >> Signed-off-by: Douglas Anderson > > > I hacked together a (still very immature) kgdb test suite[1] around the turn > of the year. Whilst its not quite solid enough for me to recommend others > deploy it except out of curiosity... so I haven't yet started yelling about > test suite failures except in the privacy of my own head. > > However I can confirm that this patch fixes one of the test suite failures I > haven't had time to blame allocate yet! > > So... > Tested-by: Daniel Thompson Thanks for your testing! ...I'll have to check out your test suite soon. > BTW is this something that should Cc: stable? It wouldn't hurt if this made it back to stable on a best-effort approach. The problem has been there since the beginning, so it's not like it's fixing a regression that cropped up in a specific version. ...but it does fix a bug, so probably Cc stable makes sense. I guess I'd leave it up to the maintainer that applies the patch? -Doug

On Thu, Mar 8, 2018 at 8:19 AM, Daniel Thompson <daniel.thompson@linaro.org> wrote:
On 05/03/18 23:43, Douglas Anderson wrote:
This is the equivalent of commit 001bf455d206 ("ARM: 8428/1: kgdb: Fix
registers on sleeping tasks") but for arm64.  Nuff said.

...well, perhaps I could also add that task_pt_regs are userspace
registers and that's not what kgdb is supposed to be reporting.  We're
supposed to be reporting kernel registers.

Signed-off-by: Douglas Anderson <dianders@chromium.org>

 I hacked together a (still very immature) kgdb test suite[1] around the turn of the year. Whilst its not quite solid enough for me to recommend others deploy it except out of curiosity... so I haven't yet started yelling about test suite failures except in the privacy of my own head.

However I can confirm that this patch fixes one of the test suite failures I haven't had time to blame allocate yet!

So...
Tested-by: Daniel Thompson <daniel.thompson@linaro.org>

BTW is this something that should Cc: stable?


Daniel.

[1] https://github.com/daniel-thompson/kgdbtest



---

Changes in v2:
- Init cpu_context in one line
- Explain that task_pt_regs are userspace

  arch/arm64/kernel/kgdb.c | 21 ++++++++++++++++-----
  1 file changed, 16 insertions(+), 5 deletions(-)

+       gdb_regs[31] = cpu_context->sp;
+       gdb_regs[32] = cpu_context->pc;
  }
    void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc)



diff --git a/arch/arm64/kernel/kgdb.c b/arch/arm64/kernel/kgdb.c
index 2122cd187f19..a20de58061a8 100644
--- a/arch/arm64/kernel/kgdb.c
+++ b/arch/arm64/kernel/kgdb.c
@@ -138,14 +138,25 @@ int dbg_set_reg(int regno, void *mem, struct pt_regs *regs)
  void
  sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *task)
  {
-       struct pt_regs *thread_regs;
+       struct cpu_context *cpu_context = &task->thread.cpu_context;
        /* Initialize to zero */
        memset((char *)gdb_regs, 0, NUMREGBYTES);
-       thread_regs = task_pt_regs(task);
-       memcpy((void *)gdb_regs, (void *)thread_regs->regs, GP_REG_BYTES);
-       /* Special case for PSTATE (check comments in asm/kgdb.h for details) */
-       dbg_get_reg(33, gdb_regs + GP_REG_BYTES, thread_regs);
+
+       gdb_regs[19] = cpu_context->x19;
+       gdb_regs[20] = cpu_context->x20;
+       gdb_regs[21] = cpu_context->x21;
+       gdb_regs[22] = cpu_context->x22;
+       gdb_regs[23] = cpu_context->x23;
+       gdb_regs[24] = cpu_context->x24;
+       gdb_regs[25] = cpu_context->x25;
+       gdb_regs[26] = cpu_context->x26;
+       gdb_regs[27] = cpu_context->x27;
+       gdb_regs[28] = cpu_context->x28;
+       gdb_regs[29] = cpu_context->fp;
+