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From: Torsten Duwe <duwe@suse.de>
To: Mark Rutland <mark.rutland@arm.com>
Cc: linux-arm-kernel@lists.infradead.org,
	Jessica Yu <jeyu@kernel.org>, Helge Deller <deller@gmx.de>,
	"James E.J. Bottomley" <James.Bottomley@hansenpartnership.com>,
	linux-kernel@vger.kernel.org, amit.kachhap@arm.com,
	catalin.marinas@arm.com, james.morse@arm.com,
	jpoimboe@redhat.com, jthierry@redhat.com,
	linux-parisc@vger.kernel.org, mingo@redhat.com,
	peterz@infradead.org, rostedt@goodmis.org, svens@stackframe.org,
	takahiro.akashi@linaro.org, will@kernel.org
Subject: Re: [PATCHv2 2/8] module/ftrace: handle patchable-function-entry
Date: Wed, 30 Oct 2019 16:03:02 +0100	[thread overview]
Message-ID: <20191030150302.GA965@suse.de> (raw)
In-Reply-To: <20191029165832.33606-3-mark.rutland@arm.com>

On Tue, Oct 29, 2019 at 04:58:26PM +0000, Mark Rutland wrote:
> When using patchable-function-entry, the compiler will record the
> callsites into a section named "__patchable_function_entries" rather
> than "__mcount_loc". Let's abstract this difference behind a new
> FTRACE_CALLSITE_SECTION, so that architectures don't have to handle this
> explicitly (e.g. with custom module linker scripts).
> 
> As parisc currently handles this explicitly, it is fixed up accordingly,
> with its custom linker script removed. Since FTRACE_CALLSITE_SECTION is
> only defined when DYNAMIC_FTRACE is selected, the parisc module loading
> code is updated to only use the definition in that case. When
> DYNAMIC_FTRACE is not selected, modules shouldn't have this section, so
> this removes some redundant work in that case.
> 
> I built parisc generic-{32,64}bit_defconfig with DYNAMIC_FTRACE enabled,
> and verified that the section made it into the .ko files for modules.

This is because of remaining #ifdeffery in include/asm-generic/vmlinux.lds.h:

#ifdef CC_USING_PATCHABLE_FUNCTION_ENTRY
#define MCOUNT_REC()    . = ALIGN(8);                           \
                        __start_mcount_loc = .;                 \
                        KEEP(*(__patchable_function_entries))   \
                        __stop_mcount_loc = .;
#else
#define MCOUNT_REC()    . = ALIGN(8);                           \
                        __start_mcount_loc = .;                 \
                        KEEP(*(__mcount_loc))                   \
                        __stop_mcount_loc = .;
#endif

Maybe you want to tackle that as well? I suggest to have at least one
FTRACE_CALLSITE_SECTION definition without double quotes. Alternatively, my
earlier solution just kept both sections, in case either one or both are
present.

                        KEEP(*(__patchable_function_entries))   \
                        KEEP(*(__mcount_loc))                   \

	Torsten

WARNING: multiple messages have this Message-ID (diff)
From: Torsten Duwe <duwe@suse.de>
To: Mark Rutland <mark.rutland@arm.com>
Cc: jthierry@redhat.com, linux-parisc@vger.kernel.org,
	peterz@infradead.org, catalin.marinas@arm.com,
	Helge Deller <deller@gmx.de>,
	jpoimboe@redhat.com, linux-kernel@vger.kernel.org,
	rostedt@goodmis.org,
	"James E.J. Bottomley" <James.Bottomley@hansenpartnership.com>,
	takahiro.akashi@linaro.org, will@kernel.org, mingo@redhat.com,
	james.morse@arm.com, Jessica Yu <jeyu@kernel.org>,
	amit.kachhap@arm.com, svens@stackframe.org,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCHv2 2/8] module/ftrace: handle patchable-function-entry
Date: Wed, 30 Oct 2019 16:03:02 +0100	[thread overview]
Message-ID: <20191030150302.GA965@suse.de> (raw)
In-Reply-To: <20191029165832.33606-3-mark.rutland@arm.com>

On Tue, Oct 29, 2019 at 04:58:26PM +0000, Mark Rutland wrote:
> When using patchable-function-entry, the compiler will record the
> callsites into a section named "__patchable_function_entries" rather
> than "__mcount_loc". Let's abstract this difference behind a new
> FTRACE_CALLSITE_SECTION, so that architectures don't have to handle this
> explicitly (e.g. with custom module linker scripts).
> 
> As parisc currently handles this explicitly, it is fixed up accordingly,
> with its custom linker script removed. Since FTRACE_CALLSITE_SECTION is
> only defined when DYNAMIC_FTRACE is selected, the parisc module loading
> code is updated to only use the definition in that case. When
> DYNAMIC_FTRACE is not selected, modules shouldn't have this section, so
> this removes some redundant work in that case.
> 
> I built parisc generic-{32,64}bit_defconfig with DYNAMIC_FTRACE enabled,
> and verified that the section made it into the .ko files for modules.

This is because of remaining #ifdeffery in include/asm-generic/vmlinux.lds.h:

#ifdef CC_USING_PATCHABLE_FUNCTION_ENTRY
#define MCOUNT_REC()    . = ALIGN(8);                           \
                        __start_mcount_loc = .;                 \
                        KEEP(*(__patchable_function_entries))   \
                        __stop_mcount_loc = .;
#else
#define MCOUNT_REC()    . = ALIGN(8);                           \
                        __start_mcount_loc = .;                 \
                        KEEP(*(__mcount_loc))                   \
                        __stop_mcount_loc = .;
#endif

Maybe you want to tackle that as well? I suggest to have at least one
FTRACE_CALLSITE_SECTION definition without double quotes. Alternatively, my
earlier solution just kept both sections, in case either one or both are
present.

                        KEEP(*(__patchable_function_entries))   \
                        KEEP(*(__mcount_loc))                   \

	Torsten

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  reply	other threads:[~2019-10-30 15:03 UTC|newest]

Thread overview: 96+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-29 16:58 [PATCHv2 0/8] arm64: ftrace cleanup + FTRACE_WITH_REGS Mark Rutland
2019-10-29 16:58 ` Mark Rutland
2019-10-29 16:58 ` [PATCHv2 1/8] ftrace: add ftrace_init_nop() Mark Rutland
2019-10-29 16:58   ` Mark Rutland
2019-10-30 15:00   ` Miroslav Benes
2019-10-30 15:00     ` Miroslav Benes
2019-11-02 12:19   ` Amit Daniel Kachhap
2019-11-02 12:19     ` Amit Daniel Kachhap
2019-11-04 13:11     ` Steven Rostedt
2019-11-04 13:11       ` Steven Rostedt
2019-11-05  6:59       ` Amit Kachhap
2019-11-05  6:59         ` Amit Kachhap
2019-11-04 13:36     ` Mark Rutland
2019-11-04 13:36       ` Mark Rutland
2019-11-05  6:47       ` Amit Kachhap
2019-11-05  6:47         ` Amit Kachhap
2019-11-06 14:15         ` Mark Rutland
2019-11-06 14:15           ` Mark Rutland
2019-11-07  4:40           ` Amit Kachhap
2019-11-07  4:40             ` Amit Kachhap
2019-11-04 13:16   ` Steven Rostedt
2019-11-04 13:16     ` Steven Rostedt
2019-11-04 13:38     ` Mark Rutland
2019-11-04 13:38       ` Mark Rutland
2019-11-04 13:53       ` Steven Rostedt
2019-11-04 13:53         ` Steven Rostedt
2019-10-29 16:58 ` [PATCHv2 2/8] module/ftrace: handle patchable-function-entry Mark Rutland
2019-10-29 16:58   ` Mark Rutland
2019-10-30 15:03   ` Torsten Duwe [this message]
2019-10-30 15:03     ` Torsten Duwe
2019-10-31  9:02     ` Mark Rutland
2019-10-31  9:02       ` Mark Rutland
2019-10-31 11:42       ` Torsten Duwe
2019-10-31 11:42         ` Torsten Duwe
2019-10-31 13:00         ` Mark Rutland
2019-10-31 13:00           ` Mark Rutland
2019-11-04 13:28           ` Steven Rostedt
2019-11-04 13:28             ` Steven Rostedt
2019-11-04 14:00             ` Mark Rutland
2019-11-04 14:00               ` Mark Rutland
2019-11-04 13:25   ` Steven Rostedt
2019-11-04 13:25     ` Steven Rostedt
2019-11-04 15:51   ` Mark Rutland
2019-11-04 15:51     ` Mark Rutland
2019-11-04 20:58     ` Helge Deller
2019-11-04 20:58       ` Helge Deller
2019-11-05  8:59   ` Miroslav Benes
2019-11-05  8:59     ` Miroslav Benes
2019-10-29 16:58 ` [PATCHv2 3/8] arm64: module: rework special section handling Mark Rutland
2019-10-29 16:58   ` Mark Rutland
2019-10-30 15:25   ` Miroslav Benes
2019-10-30 15:25     ` Miroslav Benes
2019-10-29 16:58 ` [PATCHv2 4/8] arm64: module/ftrace: intialize PLT at load time Mark Rutland
2019-10-29 16:58   ` Mark Rutland
2019-11-02 12:20   ` Amit Daniel Kachhap
2019-11-02 12:20     ` Amit Daniel Kachhap
2019-11-04 13:55     ` Mark Rutland
2019-11-04 13:55       ` Mark Rutland
2019-10-29 16:58 ` [PATCHv2 5/8] arm64: insn: add encoder for MOV (register) Mark Rutland
2019-10-29 16:58   ` Mark Rutland
2019-10-29 16:58 ` [PATCHv2 6/8] arm64: asm-offsets: add S_FP Mark Rutland
2019-10-29 16:58   ` Mark Rutland
2019-10-29 16:58 ` [PATCHv2 7/8] arm64: implement ftrace with regs Mark Rutland
2019-10-29 16:58   ` Mark Rutland
2019-11-02 12:21   ` Amit Daniel Kachhap
2019-11-02 12:21     ` Amit Daniel Kachhap
2019-11-04 13:51     ` Mark Rutland
2019-11-04 13:51       ` Mark Rutland
     [not found]   ` <CANW9uyug8WKN2fR-FmcW-C_OO_OQ_AvukM+BR7wqiJ9eFQMO9Q@mail.gmail.com>
2019-11-15  7:45     ` Torsten Duwe
2019-11-15  7:45       ` Torsten Duwe
2019-11-15 13:59     ` Mark Rutland
2019-11-15 13:59       ` Mark Rutland
2019-10-29 16:58 ` [PATCHv2 8/8] arm64: ftrace: minimize ifdeffery Mark Rutland
2019-10-29 16:58   ` Mark Rutland
2019-10-30 17:02 ` [PATCHv2 0/8] arm64: ftrace cleanup + FTRACE_WITH_REGS Torsten Duwe
2019-10-30 17:02   ` Torsten Duwe
2019-10-31 17:16 ` Torsten Duwe
2019-10-31 17:16   ` Torsten Duwe
2019-11-01  9:08   ` Mark Rutland
2019-11-01  9:08     ` Mark Rutland
2019-11-01 15:39 ` Sven Schnelle
2019-11-01 15:39   ` Sven Schnelle
2019-11-01 16:28   ` Mark Rutland
2019-11-01 16:28     ` Mark Rutland
2019-11-02 12:12 ` Amit Daniel Kachhap
2019-11-02 12:12   ` Amit Daniel Kachhap
2019-11-04 12:56   ` Will Deacon
2019-11-04 12:56     ` Will Deacon
2019-11-04 13:03     ` Amit Kachhap
2019-11-04 13:03       ` Amit Kachhap
2019-11-04 14:04       ` Mark Rutland
2019-11-04 14:04         ` Mark Rutland
2019-11-05  7:06         ` Amit Kachhap
2019-11-05  7:06           ` Amit Kachhap
2019-11-07 11:31 ` Catalin Marinas
2019-11-07 11:31   ` Catalin Marinas

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