From: Alexander A Sverdlin <alexander.sverdlin@nokia.com> To: Steven Rostedt <rostedt@goodmis.org>, Ingo Molnar <mingo@redhat.com>, Russell King <linux@armlinux.org.uk>, linux-arm-kernel@lists.infradead.org, Florian Fainelli <f.fainelli@gmail.com> Cc: Alexander Sverdlin <alexander.sverdlin@nokia.com>, linux-kernel@vger.kernel.org, Ard Biesheuvel <ard.biesheuvel@linaro.org> Subject: [PATCH v7 0/2] ARM: Implement MODULE_PLT support in FTRACE Date: Wed, 27 Jan 2021 12:09:42 +0100 [thread overview] Message-ID: <20210127110944.41813-1-alexander.sverdlin@nokia.com> (raw) From: Alexander Sverdlin <alexander.sverdlin@nokia.com> FTRACE's function tracer currently doesn't always work on ARM with MODULE_PLT option enabled. If the module is loaded too far, FTRACE's code modifier cannot cope with introduced veneers and turns the function tracer off globally. ARM64 already has a solution for the problem, refer to the following patches: arm64: ftrace: emit ftrace-mod.o contents through code arm64: module-plts: factor out PLT generation code for ftrace arm64: ftrace: fix !CONFIG_ARM64_MODULE_PLTS kernels arm64: ftrace: fix building without CONFIG_MODULES arm64: ftrace: add support for far branches to dynamic ftrace arm64: ftrace: don't validate branch via PLT in ftrace_make_nop() But the presented ARM variant has just a half of the footprint in terms of the changed LoCs. It also retains the code validation-before-modification instead of switching it off. Changelog: v7: * rebased v6: * rebased v5: * BUILD_BUG_ON() ensures fixed_plts[] always fits one PLT block * use "for" loop instead of "while" * scripts/recordmcount is filtering reloc types v4: * Fixed build without CONFIG_FUNCTION_TRACER * Reorganized pre-allocated PLTs handling in get_module_plt(), now compiler eliminates the whole FTRACE-related handling code if ARRAY_SIZE(fixed_plts) == 0 v3: * Only extend struct dyn_arch_ftrace when ARM_MODULE_PLTS is enabled v2: * As suggested by Steven Rostedt, refrain from tree-wide API modification, save module pointer in struct dyn_arch_ftrace instead (PowerPC way) Alexander Sverdlin (2): ARM: PLT: Move struct plt_entries definition to header ARM: ftrace: Add MODULE_PLTS support arch/arm/include/asm/ftrace.h | 3 +++ arch/arm/include/asm/module.h | 10 +++++++++ arch/arm/kernel/ftrace.c | 46 ++++++++++++++++++++++++++++++++++++++-- arch/arm/kernel/module-plts.c | 49 +++++++++++++++++++++++++++++++++---------- 4 files changed, 95 insertions(+), 13 deletions(-) -- 2.10.2
WARNING: multiple messages have this Message-ID (diff)
From: Alexander A Sverdlin <alexander.sverdlin@nokia.com> To: Steven Rostedt <rostedt@goodmis.org>, Ingo Molnar <mingo@redhat.com>, Russell King <linux@armlinux.org.uk>, linux-arm-kernel@lists.infradead.org, Florian Fainelli <f.fainelli@gmail.com> Cc: Alexander Sverdlin <alexander.sverdlin@nokia.com>, linux-kernel@vger.kernel.org, Ard Biesheuvel <ard.biesheuvel@linaro.org> Subject: [PATCH v7 0/2] ARM: Implement MODULE_PLT support in FTRACE Date: Wed, 27 Jan 2021 12:09:42 +0100 [thread overview] Message-ID: <20210127110944.41813-1-alexander.sverdlin@nokia.com> (raw) From: Alexander Sverdlin <alexander.sverdlin@nokia.com> FTRACE's function tracer currently doesn't always work on ARM with MODULE_PLT option enabled. If the module is loaded too far, FTRACE's code modifier cannot cope with introduced veneers and turns the function tracer off globally. ARM64 already has a solution for the problem, refer to the following patches: arm64: ftrace: emit ftrace-mod.o contents through code arm64: module-plts: factor out PLT generation code for ftrace arm64: ftrace: fix !CONFIG_ARM64_MODULE_PLTS kernels arm64: ftrace: fix building without CONFIG_MODULES arm64: ftrace: add support for far branches to dynamic ftrace arm64: ftrace: don't validate branch via PLT in ftrace_make_nop() But the presented ARM variant has just a half of the footprint in terms of the changed LoCs. It also retains the code validation-before-modification instead of switching it off. Changelog: v7: * rebased v6: * rebased v5: * BUILD_BUG_ON() ensures fixed_plts[] always fits one PLT block * use "for" loop instead of "while" * scripts/recordmcount is filtering reloc types v4: * Fixed build without CONFIG_FUNCTION_TRACER * Reorganized pre-allocated PLTs handling in get_module_plt(), now compiler eliminates the whole FTRACE-related handling code if ARRAY_SIZE(fixed_plts) == 0 v3: * Only extend struct dyn_arch_ftrace when ARM_MODULE_PLTS is enabled v2: * As suggested by Steven Rostedt, refrain from tree-wide API modification, save module pointer in struct dyn_arch_ftrace instead (PowerPC way) Alexander Sverdlin (2): ARM: PLT: Move struct plt_entries definition to header ARM: ftrace: Add MODULE_PLTS support arch/arm/include/asm/ftrace.h | 3 +++ arch/arm/include/asm/module.h | 10 +++++++++ arch/arm/kernel/ftrace.c | 46 ++++++++++++++++++++++++++++++++++++++-- arch/arm/kernel/module-plts.c | 49 +++++++++++++++++++++++++++++++++---------- 4 files changed, 95 insertions(+), 13 deletions(-) -- 2.10.2 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next reply other threads:[~2021-01-27 11:13 UTC|newest] Thread overview: 60+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-01-27 11:09 Alexander A Sverdlin [this message] 2021-01-27 11:09 ` [PATCH v7 0/2] ARM: Implement MODULE_PLT support in FTRACE Alexander A Sverdlin 2021-01-27 11:09 ` [PATCH v7 1/2] ARM: PLT: Move struct plt_entries definition to header Alexander A Sverdlin 2021-01-27 11:09 ` Alexander A Sverdlin 2021-01-27 20:25 ` Florian Fainelli 2021-01-27 20:25 ` Florian Fainelli 2021-01-27 11:09 ` [PATCH v7 2/2] ARM: ftrace: Add MODULE_PLTS support Alexander A Sverdlin 2021-01-27 11:09 ` Alexander A Sverdlin 2021-01-27 19:36 ` Florian Fainelli 2021-01-27 19:36 ` Florian Fainelli 2021-03-07 17:26 ` Qais Yousef 2021-03-07 17:26 ` Qais Yousef 2021-03-08 7:58 ` Alexander Sverdlin 2021-03-08 7:58 ` Alexander Sverdlin 2021-03-09 17:42 ` Qais Yousef 2021-03-09 17:42 ` Qais Yousef 2021-03-10 7:23 ` Alexander Sverdlin 2021-03-10 7:23 ` Alexander Sverdlin 2021-03-10 16:14 ` Florian Fainelli 2021-03-10 16:14 ` Florian Fainelli 2021-03-10 17:17 ` Alexander Sverdlin 2021-03-10 17:17 ` Alexander Sverdlin 2021-03-12 17:24 ` Qais Yousef 2021-03-12 17:24 ` Qais Yousef 2021-03-12 18:35 ` Florian Fainelli 2021-03-12 18:35 ` Florian Fainelli 2021-03-14 22:02 ` Qais Yousef 2021-03-14 22:02 ` Qais Yousef 2021-03-21 19:06 ` Qais Yousef 2021-03-21 19:06 ` Qais Yousef 2021-03-22 15:01 ` Steven Rostedt 2021-03-22 15:01 ` Steven Rostedt 2021-03-22 16:32 ` Qais Yousef 2021-03-22 16:32 ` Qais Yousef 2021-03-22 17:02 ` Alexander Sverdlin 2021-03-22 17:02 ` Alexander Sverdlin 2021-03-23 22:22 ` Qais Yousef 2021-03-23 22:22 ` Qais Yousef 2021-03-24 3:37 ` Florian Fainelli 2021-03-24 3:37 ` Florian Fainelli 2021-03-24 16:10 ` Qais Yousef 2021-03-24 16:10 ` Qais Yousef 2021-03-24 9:04 ` Alexander Sverdlin 2021-03-24 9:04 ` Alexander Sverdlin 2021-03-24 15:57 ` Qais Yousef 2021-03-24 15:57 ` Qais Yousef 2021-03-24 16:33 ` Alexander Sverdlin 2021-03-24 16:33 ` Alexander Sverdlin 2021-03-24 16:46 ` Qais Yousef 2021-03-24 16:46 ` Qais Yousef 2021-03-15 9:19 ` Alexander Sverdlin 2021-03-15 9:19 ` Alexander Sverdlin 2021-02-03 18:23 ` [PATCH v7 0/2] ARM: Implement MODULE_PLT support in FTRACE Florian Fainelli 2021-02-03 18:23 ` Florian Fainelli 2021-02-15 18:31 ` Ard Biesheuvel 2021-02-15 18:31 ` Ard Biesheuvel 2021-03-02 8:29 ` Linus Walleij 2021-03-02 8:29 ` Linus Walleij 2021-03-02 10:00 ` Alexander Sverdlin 2021-03-02 10:00 ` Alexander Sverdlin
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