linux-arm-kernel.lists.infradead.org archive mirror
 help / color / mirror / Atom feed
From: Mark Rutland <mark.rutland@arm.com>
To: madvenka@linux.microsoft.com
Cc: broonie@kernel.org, jpoimboe@redhat.com, ardb@kernel.org,
	nobuta.keiya@fujitsu.com, sjitindarsingh@gmail.com,
	catalin.marinas@arm.com, will@kernel.org, jmorris@namei.org,
	linux-arm-kernel@lists.infradead.org,
	live-patching@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v13 05/11] arm64: Copy the task argument to unwind_state
Date: Tue, 15 Feb 2022 13:22:42 +0000	[thread overview]
Message-ID: <YgupIuJgL7nreT+1@FVFF77S0Q05N> (raw)
In-Reply-To: <20220117145608.6781-6-madvenka@linux.microsoft.com>

On Mon, Jan 17, 2022 at 08:56:02AM -0600, madvenka@linux.microsoft.com wrote:
> From: "Madhavan T. Venkataraman" <madvenka@linux.microsoft.com>
> 
> Copy the task argument passed to arch_stack_walk() to unwind_state so that
> it can be passed to unwind functions via unwind_state rather than as a
> separate argument. The task is a fundamental part of the unwind state.
> 
> Signed-off-by: Madhavan T. Venkataraman <madvenka@linux.microsoft.com>
> ---
>  arch/arm64/include/asm/stacktrace.h |  3 +++
>  arch/arm64/kernel/stacktrace.c      | 29 ++++++++++++++++-------------
>  2 files changed, 19 insertions(+), 13 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/stacktrace.h b/arch/arm64/include/asm/stacktrace.h
> index 41ec360515f6..af423f5d7ad8 100644
> --- a/arch/arm64/include/asm/stacktrace.h
> +++ b/arch/arm64/include/asm/stacktrace.h
> @@ -51,6 +51,8 @@ struct stack_info {
>   * @kr_cur:      When KRETPROBES is selected, holds the kretprobe instance
>   *               associated with the most recently encountered replacement lr
>   *               value.
> + *
> + * @task:        Pointer to the task structure.

Can we please say:

	@task:	The task being unwound.

>   */
>  struct unwind_state {
>  	unsigned long fp;
> @@ -61,6 +63,7 @@ struct unwind_state {
>  #ifdef CONFIG_KRETPROBES
>  	struct llist_node *kr_cur;
>  #endif
> +	struct task_struct *task;
>  };
>  
>  extern void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk,
> diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c
> index b2b568e5deba..1b32e55735aa 100644
> --- a/arch/arm64/kernel/stacktrace.c
> +++ b/arch/arm64/kernel/stacktrace.c
> @@ -33,8 +33,10 @@
>   */
>  
>  
> -static void unwind_init_common(struct unwind_state *state)
> +static void unwind_init_common(struct unwind_state *state,
> +			       struct task_struct *task)
>  {
> +	state->task = task;
>  #ifdef CONFIG_KRETPROBES
>  	state->kr_cur = NULL;
>  #endif
> @@ -57,9 +59,10 @@ static void unwind_init_common(struct unwind_state *state)
>   * TODO: document requirements here.
>   */
>  static inline void unwind_init_from_regs(struct unwind_state *state,
> +					 struct task_struct *task,

Please drop the `task` parameter here ...

>  					 struct pt_regs *regs)
>  {
> -	unwind_init_common(state);
> +	unwind_init_common(state, task);

... and make this:

	unwind_init_common(state, current);

... since that way it's *impossible* to have ismatched parameters, which is one
of the reasons for having separate functions in the first place.

>  	state->fp = regs->regs[29];
>  	state->pc = regs->pc;
> @@ -71,9 +74,10 @@ static inline void unwind_init_from_regs(struct unwind_state *state,
>   * Note: this is always inlined, and we expect our caller to be a noinline
>   * function, such that this starts from our caller's caller.
>   */
> -static __always_inline void unwind_init_from_current(struct unwind_state *state)
> +static __always_inline void unwind_init_from_current(struct unwind_state *state,
> +						     struct task_struct *task)
>  {
> -	unwind_init_common(state);
> +	unwind_init_common(state, task);

Same comments as for unwind_init_from_regs(): please drop the `task` parameter
and hard-code `current` in the call to unwind_init_common().

>  	state->fp = (unsigned long)__builtin_frame_address(1);
>  	state->pc = (unsigned long)__builtin_return_address(0);
> @@ -87,7 +91,7 @@ static __always_inline void unwind_init_from_current(struct unwind_state *state)
>  static inline void unwind_init_from_task(struct unwind_state *state,
>  					 struct task_struct *task)
>  {
> -	unwind_init_common(state);
> +	unwind_init_common(state, task);
>  
>  	state->fp = thread_saved_fp(task);
>  	state->pc = thread_saved_pc(task);
> @@ -100,11 +104,11 @@ static inline void unwind_init_from_task(struct unwind_state *state,
>   * records (e.g. a cycle), determined based on the location and fp value of A
>   * and the location (but not the fp value) of B.
>   */
> -static int notrace unwind_next(struct task_struct *tsk,
> -			       struct unwind_state *state)
> +static int notrace unwind_next(struct unwind_state *state)
>  {
>  	unsigned long fp = state->fp;
>  	struct stack_info info;
> +	struct task_struct *tsk = state->task;
>  
>  	/* Final frame; nothing to unwind */
>  	if (fp == (unsigned long)task_pt_regs(tsk)->stackframe)
> @@ -176,8 +180,7 @@ static int notrace unwind_next(struct task_struct *tsk,
>  }
>  NOKPROBE_SYMBOL(unwind_next);
>  
> -static void notrace unwind(struct task_struct *tsk,
> -			   struct unwind_state *state,
> +static void notrace unwind(struct unwind_state *state,
>  			   bool (*fn)(void *, unsigned long), void *data)
>  {
>  	while (1) {
> @@ -185,7 +188,7 @@ static void notrace unwind(struct task_struct *tsk,
>  
>  		if (!fn(data, state->pc))
>  			break;
> -		ret = unwind_next(tsk, state);
> +		ret = unwind_next(state);
>  		if (ret < 0)
>  			break;
>  	}
> @@ -232,11 +235,11 @@ noinline notrace void arch_stack_walk(stack_trace_consume_fn consume_entry,
>  	struct unwind_state state;
>  
>  	if (regs)
> -		unwind_init_from_regs(&state, regs);
> +		unwind_init_from_regs(&state, task, regs);
>  	else if (task == current)
> -		unwind_init_from_current(&state);
> +		unwind_init_from_current(&state, task);
>  	else
>  		unwind_init_from_task(&state, task);

As above we shouldn't need these two changes.

For the regs case we might want to sanity-check that task == current.

> -	unwind(task, &state, consume_entry, cookie);
> +	unwind(&state, consume_entry, cookie);

Otherwise, this looks good to me.

Thanks,
Mark.

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  parent reply	other threads:[~2022-02-15 13:24 UTC|newest]

Thread overview: 75+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <95691cae4f4504f33d0fc9075541b1e7deefe96f>
2022-01-17 14:55 ` [PATCH v13 00/11] arm64: Reorganize the unwinder and implement stack trace reliability checks madvenka
2022-01-17 14:55   ` [PATCH v13 01/11] arm64: Remove NULL task check from unwind_frame() madvenka
2022-01-17 14:55   ` [PATCH v13 02/11] arm64: Rename unwinder functions madvenka
2022-01-17 14:56   ` [PATCH v13 03/11] arm64: Rename stackframe to unwind_state madvenka
2022-01-17 14:56   ` [PATCH v13 04/11] arm64: Split unwind_init() madvenka
2022-02-02 18:44     ` Mark Brown
2022-02-03  0:26       ` Madhavan T. Venkataraman
2022-02-03  0:39         ` Madhavan T. Venkataraman
2022-02-03 11:29           ` Mark Brown
2022-02-15 13:07     ` Mark Rutland
2022-02-15 18:04       ` Madhavan T. Venkataraman
2022-01-17 14:56   ` [PATCH v13 05/11] arm64: Copy the task argument to unwind_state madvenka
2022-02-02 18:45     ` Mark Brown
2022-02-15 13:22     ` Mark Rutland [this message]
2022-02-22 16:53       ` Madhavan T. Venkataraman
2022-01-17 14:56   ` [PATCH v13 06/11] arm64: Use stack_trace_consume_fn and rename args to unwind() madvenka
2022-02-02 18:46     ` Mark Brown
2022-02-03  0:34       ` Madhavan T. Venkataraman
2022-02-03 11:30         ` Mark Brown
2022-02-03 14:45           ` Madhavan T. Venkataraman
2022-02-15 13:39     ` Mark Rutland
2022-02-15 18:12       ` Madhavan T. Venkataraman
2022-03-07 16:51       ` Madhavan T. Venkataraman
2022-03-07 17:01         ` Mark Brown
2022-03-08 22:00           ` Madhavan T. Venkataraman
2022-03-09 11:47             ` Mark Brown
2022-03-09 15:34               ` Madhavan T. Venkataraman
2022-03-10  8:33               ` Miroslav Benes
2022-03-10 12:36                 ` Madhavan T. Venkataraman
2022-03-16  3:43               ` Josh Poimboeuf
2022-04-08 14:44         ` Mark Rutland
2022-04-08 17:58           ` Mark Rutland
2022-04-10 17:42             ` Madhavan T. Venkataraman
2022-04-10 17:33           ` Madhavan T. Venkataraman
2022-04-10 17:45           ` Madhavan T. Venkataraman
2022-01-17 14:56   ` [PATCH v13 07/11] arm64: Make the unwind loop in unwind() similar to other architectures madvenka
2022-01-17 14:56   ` [PATCH v13 08/11] arm64: Introduce stack trace reliability checks in the unwinder madvenka
2022-01-17 14:56   ` [PATCH v13 09/11] arm64: Create a list of SYM_CODE functions, check return PC against list madvenka
2022-01-17 14:56   ` [PATCH v13 10/11] arm64: Introduce arch_stack_walk_reliable() madvenka
2022-01-17 14:56   ` [PATCH v13 11/11] arm64: Select HAVE_RELIABLE_STACKTRACE madvenka
2022-01-25  5:21     ` nobuta.keiya
2022-01-25 13:43       ` Madhavan T. Venkataraman
2022-01-26 10:20         ` nobuta.keiya
2022-01-26 17:14           ` Madhavan T. Venkataraman
2022-01-27  1:13             ` nobuta.keiya
2022-01-26 17:16       ` Mark Brown
2022-04-07 20:25 ` [RFC PATCH v1 0/9] arm64: livepatch: Use DWARF Call Frame Information for frame pointer validation madvenka
2022-04-07 20:25   ` [RFC PATCH v1 1/9] objtool: Parse DWARF Call Frame Information in object files madvenka
2022-04-07 20:25   ` [RFC PATCH v1 2/9] objtool: Generate DWARF rules and place them in a special section madvenka
2022-04-07 20:25   ` [RFC PATCH v1 3/9] dwarf: Build the kernel with DWARF information madvenka
2022-04-07 20:25   ` [RFC PATCH v1 4/9] dwarf: Implement DWARF rule processing in the kernel madvenka
2022-04-07 20:25   ` [RFC PATCH v1 5/9] dwarf: Implement DWARF support for modules madvenka
2022-04-07 20:25   ` [RFC PATCH v1 6/9] arm64: unwinder: Add a reliability check in the unwinder based on DWARF CFI madvenka
2022-04-07 20:25   ` [RFC PATCH v1 7/9] arm64: dwarf: Implement unwind hints madvenka
2022-04-07 20:25   ` [RFC PATCH v1 8/9] dwarf: Miscellaneous changes required for enabling livepatch madvenka
2022-04-07 20:25   ` [RFC PATCH v1 9/9] dwarf: Enable livepatch for ARM64 madvenka
2022-04-08  0:21   ` [RFC PATCH v1 0/9] arm64: livepatch: Use DWARF Call Frame Information for frame pointer validation Josh Poimboeuf
2022-04-08 11:41     ` Peter Zijlstra
2022-04-11 17:26       ` Madhavan T. Venkataraman
2022-04-11 17:18     ` Madhavan T. Venkataraman
2022-04-12  8:32       ` Chen Zhongjin
2022-04-16  0:56         ` Josh Poimboeuf
2022-04-18 12:28           ` Chen Zhongjin
2022-04-18 16:11             ` Josh Poimboeuf
2022-04-18 18:38               ` Madhavan T. Venkataraman
     [not found]       ` <844b3ede-eddb-cbe6-80e0-3529e2da2eb6@huawei.com>
2022-04-12 17:27         ` Madhavan T. Venkataraman
2022-04-16  1:07       ` Josh Poimboeuf
2022-04-14 14:11     ` Madhavan T. Venkataraman
2022-04-08 10:55   ` Peter Zijlstra
2022-04-08 11:54     ` Peter Zijlstra
2022-04-08 14:34       ` Josh Poimboeuf
2022-04-10 17:47     ` Madhavan T. Venkataraman
2022-04-11 16:34       ` Josh Poimboeuf
2022-04-08 12:06   ` Peter Zijlstra
2022-04-11 17:35     ` Madhavan T. Venkataraman

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=YgupIuJgL7nreT+1@FVFF77S0Q05N \
    --to=mark.rutland@arm.com \
    --cc=ardb@kernel.org \
    --cc=broonie@kernel.org \
    --cc=catalin.marinas@arm.com \
    --cc=jmorris@namei.org \
    --cc=jpoimboe@redhat.com \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=live-patching@vger.kernel.org \
    --cc=madvenka@linux.microsoft.com \
    --cc=nobuta.keiya@fujitsu.com \
    --cc=sjitindarsingh@gmail.com \
    --cc=will@kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).