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From: Steven Rostedt <rostedt@goodmis.org>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Peter Zijlstra <peterz@infradead.org>,
	Will Deacon <will@kernel.org>,
	"the arch/x86 maintainers" <x86@kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	bristot@redhat.com, Jason Baron <jbaron@akamai.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@kernel.org>,
	namit@vmware.com, "H. Peter Anvin" <hpa@zytor.com>,
	Andy Lutomirski <luto@kernel.org>,
	Ard Biesheuvel <ard.biesheuvel@linaro.org>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	Jessica Yu <jeyu@kernel.org>,
	Alexei Starovoitov <alexei.starovoitov@gmail.com>,
	Mark Rutland <mark.rutland@arm.com>,
	James Morse <james.morse@arm.com>,
	Russell King <rmk+kernel@armlinux.org.uk>,
	Rabin Vincent <rabin@rab.in>, Nicolas Pitre <nico@fluxnic.net>
Subject: Re: [PATCH -v5mkII 13/17] arm/ftrace: Use __patch_text()
Date: Wed, 8 Jan 2020 09:16:28 -0500	[thread overview]
Message-ID: <20200108091628.7e548401@gandalf.local.home> (raw)
In-Reply-To: <CAK8P3a0MJGpg6AkmwRL6o7TCPOQXSMDShutigvBjeOMDn0BHaA@mail.gmail.com>

On Wed, 8 Jan 2020 13:22:52 +0100
Arnd Bergmann <arnd@arndb.de> wrote:

> On Wed, Nov 13, 2019 at 10:29 AM Peter Zijlstra <peterz@infradead.org> wrote:
> > @@ -49,8 +49,8 @@ obj-$(CONFIG_HAVE_ARM_SCU)    += smp_scu.o
> >  obj-$(CONFIG_HAVE_ARM_TWD)     += smp_twd.o
> >  obj-$(CONFIG_ARM_ARCH_TIMER)   += arch_timer.o
> >  obj-$(CONFIG_FUNCTION_TRACER)  += entry-ftrace.o
> > -obj-$(CONFIG_DYNAMIC_FTRACE)   += ftrace.o insn.o
> > -obj-$(CONFIG_FUNCTION_GRAPH_TRACER)    += ftrace.o insn.o
> > +obj-$(CONFIG_DYNAMIC_FTRACE)   += ftrace.o insn.o patch.o
> > +obj-$(CONFIG_FUNCTION_GRAPH_TRACER)    += ftrace.o insn.o patch.o
> >  obj-$(CONFIG_JUMP_LABEL)       += jump_label.o insn.o patch.o
> >  obj-$(CONFIG_KEXEC)            += machine_kexec.o relocate_kernel.o  
> 
> This broke randconfig builds with big-endian ARMv5:
> 
> ../arch/arm/kernel/patch.c: In function '__patch_text_real':
> ../arch/arm/kernel/patch.c:94:11: error: implicit declaration of
> function '__opcode_to_mem_thumb32'
> [-Werror=implicit-function-declaration]
>     insn = __opcode_to_mem_thumb32(insn);
>            ^~~~~~~~~~~~~~~~~~~~~~~
> 
> The problem is that we don't have a BE32 definition of
> __opcode_to_mem_thumb32, mostly because no hardware
> supports that.
> 
> One possible workaround is a big ugly:
> 
> diff --git a/arch/arm/kernel/patch.c b/arch/arm/kernel/patch.c
> index d0a05a3bdb96..1067fd122897 100644
> --- a/arch/arm/kernel/patch.c
> +++ b/arch/arm/kernel/patch.c
> @@ -90,9 +90,11 @@ void __kprobes __patch_text_real(void *addr,
> unsigned int insn, bool remap)
> 
>                 size = sizeof(u32);
>         } else {
> +#ifdef CONFIG_THUMB2_KERNEL
>                 if (thumb2)

If we change the above to:

		if (IS_ENABLED(CONFIG_THUMB2_KERNEL) && thumb2)

Would the compiler optmize out __opcode_to_mem_thumb32(). We would need
to add a declaration for it, but wont need to define it. At least we
wont have nasty #ifdef logic in the code.

-- Steve

>                         insn = __opcode_to_mem_thumb32(insn);
>                 else
> +#endif
>                         insn = __opcode_to_mem_arm(insn);
> 
>                 *(u32 *)waddr = insn;
> 
> 
> Any other suggestions?
> 
>        Arnd


  reply	other threads:[~2020-01-08 14:16 UTC|newest]

Thread overview: 106+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-11 13:12 [PATCH -v5 00/17] Rewrite x86/ftrace to use text_poke (and more) Peter Zijlstra
2019-11-11 13:12 ` [PATCH -v5 01/17] x86/alternatives: Teach text_poke_bp() to emulate instructions Peter Zijlstra
2019-11-15  9:43   ` [tip: core/kprobes] " tip-bot2 for Peter Zijlstra
2019-11-11 13:12 ` [PATCH -v5 02/17] x86/alternatives: Update int3_emulate_push() comment Peter Zijlstra
2019-11-15  9:43   ` [tip: core/kprobes] " tip-bot2 for Peter Zijlstra
2019-12-04  8:33   ` tip-bot2 for Peter Zijlstra
2019-11-11 13:12 ` [PATCH -v5 03/17] x86/alternatives,jump_label: Provide better text_poke() batching interface Peter Zijlstra
2019-11-15  9:43   ` [tip: core/kprobes] x86/alternatives, jump_label: " tip-bot2 for Peter Zijlstra
2019-12-04  8:33   ` tip-bot2 for Peter Zijlstra
2019-11-11 13:12 ` [PATCH -v5 04/17] x86/alternatives: Add and use text_gen_insn() helper Peter Zijlstra
2019-11-12 17:10   ` Steven Rostedt
2019-11-12 22:25     ` Peter Zijlstra
2019-11-15  9:43   ` [tip: core/kprobes] " tip-bot2 for Peter Zijlstra
2019-12-04  8:33   ` tip-bot2 for Peter Zijlstra
2019-11-11 13:12 ` [PATCH -v5 05/17] x86/ftrace: Use text_poke() Peter Zijlstra
2019-11-12 18:25   ` Steven Rostedt
2019-11-12 22:24     ` Peter Zijlstra
2019-11-12 22:48       ` Steven Rostedt
2019-11-13  9:01         ` Peter Zijlstra
2019-11-13 14:27           ` Steven Rostedt
2019-11-14 13:18             ` Peter Zijlstra
2019-11-14 13:56               ` Steven Rostedt
2019-11-14 14:05                 ` Peter Zijlstra
2019-11-13  8:53       ` Peter Zijlstra
2019-11-15  9:43   ` [tip: core/kprobes] " tip-bot2 for Peter Zijlstra
2019-11-16 20:46     ` Borislav Petkov
2019-11-18 17:35       ` [PATCH] x86/ftrace: Mark ftrace_modify_code_direct() __ref Borislav Petkov
2019-11-18 17:52         ` Steven Rostedt
2019-11-19  9:55       ` [tip: core/kprobes] " tip-bot2 for Borislav Petkov
2019-12-04  8:33       ` tip-bot2 for Borislav Petkov
2019-12-04  8:33   ` [tip: core/kprobes] x86/ftrace: Use text_poke() tip-bot2 for Peter Zijlstra
2019-11-11 13:12 ` [PATCH -v5 06/17] x86/mm: Remove set_kernel_text_r[ow]() Peter Zijlstra
2019-11-15  9:43   ` [tip: core/kprobes] " tip-bot2 for Peter Zijlstra
2019-12-04  8:33   ` tip-bot2 for Peter Zijlstra
2019-11-11 13:12 ` [PATCH -v5 07/17] x86/alternative: Add text_opcode_size() Peter Zijlstra
2019-11-15  9:43   ` [tip: core/kprobes] " tip-bot2 for Peter Zijlstra
2019-12-04  8:33   ` tip-bot2 for Peter Zijlstra
2019-11-11 13:13 ` [PATCH -v5 08/17] x86/ftrace: Use text_gen_insn() Peter Zijlstra
2019-11-15  9:43   ` [tip: core/kprobes] " tip-bot2 for Peter Zijlstra
2019-12-04  8:33   ` tip-bot2 for Peter Zijlstra
2019-11-11 13:13 ` [PATCH -v5 09/17] x86/alternative: Remove text_poke_loc::len Peter Zijlstra
2019-11-15  9:43   ` [tip: core/kprobes] " tip-bot2 for Peter Zijlstra
2019-12-04  8:33   ` tip-bot2 for Peter Zijlstra
2019-11-11 13:13 ` [PATCH -v5 10/17] x86/alternative: Shrink text_poke_loc Peter Zijlstra
2019-11-15  9:43   ` [tip: core/kprobes] " tip-bot2 for Peter Zijlstra
2019-12-04  8:33   ` tip-bot2 for Peter Zijlstra
2019-11-11 13:13 ` [PATCH -v5 11/17] x86/kprobes: Convert to text-patching.h Peter Zijlstra
2019-11-19 16:56   ` [tip: core/kprobes] " tip-bot2 for Peter Zijlstra
2019-12-04  8:33   ` tip-bot2 for Peter Zijlstra
2019-11-11 13:13 ` [PATCH -v5 12/17] x86/kprobes: Fix ordering Peter Zijlstra
2019-11-13 14:31   ` Paul E. McKenney
2019-11-13 15:42   ` Mathieu Desnoyers
2019-11-14 13:53     ` Peter Zijlstra
2019-11-14 15:06       ` Mathieu Desnoyers
2019-11-14 15:13         ` Paul E. McKenney
2019-11-14 15:22           ` Mathieu Desnoyers
2019-11-14 15:28             ` Peter Zijlstra
2019-11-14 15:30               ` Mathieu Desnoyers
2019-11-14 15:42                 ` Peter Zijlstra
2019-11-14 15:58                   ` Peter Zijlstra
2019-11-19 16:56   ` [tip: core/kprobes] x86/kprobes: Fix ordering while text-patching tip-bot2 for Peter Zijlstra
2019-12-04  8:33   ` tip-bot2 for Peter Zijlstra
2019-11-11 13:13 ` [PATCH -v5 13/17] arm/ftrace: Use __patch_text_real() Peter Zijlstra
2019-11-11 16:47   ` Will Deacon
2019-11-11 17:19     ` Peter Zijlstra
2019-11-11 17:25       ` Peter Zijlstra
2019-11-12 11:29         ` Will Deacon
2019-11-13  9:26           ` [PATCH -v5mkII 13/17] arm/ftrace: Use __patch_text() Peter Zijlstra
2019-11-19 16:56             ` [tip: core/kprobes] " tip-bot2 for Peter Zijlstra
2019-12-04  8:33             ` tip-bot2 for Peter Zijlstra
2020-01-22 21:26               ` Dmitry Osipenko
2020-02-07 10:17                 ` Peter Zijlstra
2020-02-07 10:26                   ` Peter Zijlstra
2020-02-07 11:27                 ` Peter Zijlstra
2020-02-07 16:47                   ` Dmitry Osipenko
2020-01-08 12:22             ` [PATCH -v5mkII 13/17] " Arnd Bergmann
2020-01-08 14:16               ` Steven Rostedt [this message]
2020-01-08 14:22                 ` Arnd Bergmann
2019-11-11 13:13 ` [PATCH -v5 14/17] module: Remove set_all_modules_text_*() Peter Zijlstra
2019-11-19 16:56   ` [tip: core/kprobes] " tip-bot2 for Peter Zijlstra
2019-12-04  8:33   ` tip-bot2 for Peter Zijlstra
2019-11-11 13:13 ` [PATCH -v5 15/17] ftrace: Rework event_create_dir() Peter Zijlstra
2019-11-14 14:07   ` Steven Rostedt
2019-11-19 16:56   ` [tip: core/kprobes] " tip-bot2 for Peter Zijlstra
2019-12-04  8:33   ` tip-bot2 for Peter Zijlstra
2019-11-11 13:13 ` [PATCH -v5 16/17] x86/kprobe: Add comments to arch_{,un}optimize_kprobes() Peter Zijlstra
2019-11-19 16:56   ` [tip: core/kprobes] " tip-bot2 for Peter Zijlstra
2019-12-04  8:33   ` tip-bot2 for Peter Zijlstra
2019-11-11 13:13 ` [PATCH -v5 17/17] x86/alternative: Use INT3_INSN_SIZE Peter Zijlstra
2019-11-19 16:56   ` [tip: core/kprobes] x86/alternatives: " tip-bot2 for Peter Zijlstra
2019-12-04  8:33   ` tip-bot2 for Peter Zijlstra
2019-11-11 19:47 ` [PATCH -v5 00/17] Rewrite x86/ftrace to use text_poke (and more) Alexei Starovoitov
2019-11-11 20:39   ` Peter Zijlstra
2019-11-11 20:42   ` Peter Zijlstra
2019-11-11 20:56     ` Alexei Starovoitov
2019-11-12 18:26 ` Steven Rostedt
2019-11-25  3:55 ` Masami Hiramatsu
2019-11-25  6:47   ` Masami Hiramatsu
2019-11-25 17:32   ` Steven Rostedt
2019-11-26  0:11     ` Masami Hiramatsu
2019-11-26  8:58       ` Masami Hiramatsu
2019-11-26  9:58         ` Masami Hiramatsu
2019-11-26 23:48           ` Masami Hiramatsu
     [not found]             ` <CAADnVQK4twuXzFhD-qLHmCVK0n1h-GDENQLu+4PVV3Hp++R6kQ@mail.gmail.com>
2019-11-27  4:32               ` Alexei Starovoitov
2019-11-27  5:01                 ` Alexei Starovoitov
2019-11-27  6:41                 ` Masami Hiramatsu

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