From: "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>
To: Christophe Leroy <christophe.leroy@csgroup.eu>,
Jiri Kosina <jikos@kernel.org>,
Joe Lawrence <joe.lawrence@redhat.com>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Miroslav Benes <mbenes@suse.cz>, Ingo Molnar <mingo@redhat.com>,
Petr Mladek <pmladek@suse.com>,
Steven Rostedt <rostedt@goodmis.org>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
"live-patching@vger.kernel.org" <live-patching@vger.kernel.org>
Subject: Re: [PATCH v2 08/13] powerpc/ftrace: Prepare PPC64's ftrace_caller() for CONFIG_DYNAMIC_FTRACE_WITH_ARGS
Date: Mon, 14 Feb 2022 20:49:57 +0530 [thread overview]
Message-ID: <1644851672.d8a13a7hsf.naveen@linux.ibm.com> (raw)
In-Reply-To: <850817333cc76593699032e8e9a70d8c36e1af1e.1640017960.git.christophe.leroy@csgroup.eu>
Hi Christophe,
Thanks for your work enabling DYNAMIC_FTRACE_WITH_ARGS on powerpc. Sorry
for the late review on this series, but I have a few comments below.
Christophe Leroy wrote:
> In order to implement CONFIG_DYNAMIC_FTRACE_WITH_ARGS, change ftrace_caller()
> to handle LIVEPATCH the same way as frace_caller_regs().
>
> Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
> ---
> .../powerpc/kernel/trace/ftrace_64_mprofile.S | 25 ++++++++++++++-----
> 1 file changed, 19 insertions(+), 6 deletions(-)
I think we also need to save r1 into pt_regs so that the stack pointer
is available in the callbacks.
Other than that, a few minor nits below...
>
> diff --git a/arch/powerpc/kernel/trace/ftrace_64_mprofile.S b/arch/powerpc/kernel/trace/ftrace_64_mprofile.S
> index d636fc755f60..f6f787819273 100644
> --- a/arch/powerpc/kernel/trace/ftrace_64_mprofile.S
> +++ b/arch/powerpc/kernel/trace/ftrace_64_mprofile.S
> @@ -172,14 +172,19 @@ _GLOBAL(ftrace_caller)
> addi r3, r3, function_trace_op@toc@l
> ld r5, 0(r3)
>
> +#ifdef CONFIG_LIVEPATCH_64
> + SAVE_GPR(14, r1)
> + mr r14,r7 /* remember old NIP */
^ add a space
> +#endif
Please add a blank line here, to match the formatting for the rest of
this file.
> /* Calculate ip from nip-4 into r3 for call below */
> subi r3, r7, MCOUNT_INSN_SIZE
>
> /* Put the original return address in r4 as parent_ip */
> + std r0, _LINK(r1)
> mr r4, r0
>
> - /* Set pt_regs to NULL */
> - li r6, 0
> + /* Load &pt_regs in r6 for call below */
> + addi r6, r1 ,STACK_FRAME_OVERHEAD
^^ incorrect spacing
>
> /* ftrace_call(r3, r4, r5, r6) */
> .globl ftrace_call
> @@ -189,6 +194,10 @@ ftrace_call:
>
> ld r3, _NIP(r1)
> mtctr r3
Another blank line here.
> +#ifdef CONFIG_LIVEPATCH_64
> + cmpd r14, r3 /* has NIP been altered? */
> + REST_GPR(14, r1)
> +#endif
>
> /* Restore gprs */
> REST_GPRS(3, 10, r1)
> @@ -196,13 +205,17 @@ ftrace_call:
> /* Restore callee's TOC */
> ld r2, 24(r1)
>
> + /* Restore possibly modified LR */
> + ld r0, _LINK(r1)
> + mtlr r0
> +
> /* Pop our stack frame */
> addi r1, r1, SWITCH_FRAME_SIZE
>
> - /* Reload original LR */
> - ld r0, LRSAVE(r1)
> - mtlr r0
> -
> +#ifdef CONFIG_LIVEPATCH_64
> + /* Based on the cmpd above, if the NIP was altered handle livepatch */
> + bne- livepatch_handler
> +#endif
Here too.
> /* Handle function_graph or go back */
> b ftrace_caller_common
>
- Naveen
next prev parent reply other threads:[~2022-02-14 15:20 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-20 16:37 [PATCH v2 00/13] Implement livepatch on PPC32 and more Christophe Leroy
2021-12-20 16:38 ` [PATCH v2 01/13] livepatch: Fix build failure on 32 bits processors Christophe Leroy
2021-12-22 13:47 ` Miroslav Benes
2022-01-04 19:35 ` Joe Lawrence
2021-12-20 16:38 ` [PATCH v2 02/13] tracing: Fix selftest config check for function graph start up test Christophe Leroy
2022-02-24 13:43 ` Christophe Leroy
2022-02-24 14:53 ` Steven Rostedt
2022-02-24 15:13 ` Christophe Leroy
2022-02-24 15:17 ` Steven Rostedt
2022-02-25 2:42 ` Michael Ellerman
2021-12-20 16:38 ` [PATCH v2 03/13] powerpc/module_32: Fix livepatching for RO modules Christophe Leroy
2022-01-04 19:44 ` Joe Lawrence
2021-12-20 16:38 ` [PATCH v2 04/13] powerpc/ftrace: Add support for livepatch to PPC32 Christophe Leroy
2021-12-22 14:00 ` Miroslav Benes
2021-12-20 16:38 ` [PATCH v2 05/13] powerpc/ftrace: Don't save again LR in ftrace_regs_caller() on PPC32 Christophe Leroy
2021-12-20 16:38 ` [PATCH v2 06/13] powerpc/ftrace: Simplify PPC32's return_to_handler() Christophe Leroy
2021-12-20 16:38 ` [PATCH v2 07/13] powerpc/ftrace: Prepare PPC32's ftrace_caller() for CONFIG_DYNAMIC_FTRACE_WITH_ARGS Christophe Leroy
2021-12-20 16:38 ` [PATCH v2 08/13] powerpc/ftrace: Prepare PPC64's " Christophe Leroy
2022-02-14 15:19 ` Naveen N. Rao [this message]
2021-12-20 16:38 ` [PATCH v2 09/13] powerpc/ftrace: Implement CONFIG_DYNAMIC_FTRACE_WITH_ARGS Christophe Leroy
2021-12-22 14:19 ` Miroslav Benes
2022-02-14 15:25 ` Naveen N. Rao
2022-02-15 8:00 ` Christophe Leroy
2022-02-15 11:05 ` Michael Ellerman
2022-02-15 13:36 ` Naveen N. Rao
2022-02-15 14:28 ` Christophe Leroy
2022-02-15 14:51 ` Christophe Leroy
2022-02-15 16:25 ` Naveen N. Rao
2022-02-16 13:04 ` Heiko Carstens
2022-02-16 13:27 ` Sven Schnelle
2022-02-15 14:38 ` Steven Rostedt
2022-02-15 16:26 ` Naveen N. Rao
2021-12-20 16:38 ` [PATCH v2 10/13] powerpc/ftrace: Refactor ftrace_{en/dis}able_ftrace_graph_caller Christophe Leroy
2021-12-20 16:38 ` [PATCH v2 11/13] powerpc/ftrace: directly call of function graph tracer by ftrace caller Christophe Leroy
2022-02-14 17:24 ` Naveen N. Rao
2022-02-14 19:03 ` Steven Rostedt
2021-12-20 16:38 ` [PATCH v2 12/13] powerpc/ftrace: Prepare ftrace_64_mprofile.S for reuse by PPC32 Christophe Leroy
2022-02-14 17:51 ` Naveen N. Rao
2022-02-15 8:33 ` Christophe Leroy
2021-12-20 16:38 ` [PATCH v2 13/13] powerpc/ftrace: Remove ftrace_32.S Christophe Leroy
2022-02-11 7:41 ` [PATCH] Fixup for next-test 3a1a8f078670 ("powerpc/ftrace: Remove ftrace_32.S") Christophe Leroy
2022-02-16 12:26 ` [PATCH v2 00/13] Implement livepatch on PPC32 and more Michael Ellerman
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