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From: David Laight <David.Laight@ACULAB.COM>
To: 'Mark Rutland' <mark.rutland@arm.com>,
	"linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>
Cc: "catalin.marinas@arm.com" <catalin.marinas@arm.com>,
	"lenb@kernel.org" <lenb@kernel.org>,
	"linux-acpi@vger.kernel.org" <linux-acpi@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"mhiramat@kernel.org" <mhiramat@kernel.org>,
	"ndesaulniers@google.com" <ndesaulniers@google.com>,
	"ojeda@kernel.org" <ojeda@kernel.org>,
	"peterz@infradead.org" <peterz@infradead.org>,
	"rafael.j.wysocki@intel.com" <rafael.j.wysocki@intel.com>,
	"revest@chromium.org" <revest@chromium.org>,
	"robert.moore@intel.com" <robert.moore@intel.com>,
	"rostedt@goodmis.org" <rostedt@goodmis.org>,
	"will@kernel.org" <will@kernel.org>
Subject: RE: [PATCH 0/8] arm64/ftrace: Add support for DYNAMIC_FTRACE_WITH_CALL_OPS
Date: Tue, 10 Jan 2023 08:55:58 +0000	[thread overview]
Message-ID: <34e0144b19e149d99719a5ffc834f228@AcuMS.aculab.com> (raw)
In-Reply-To: <20230109135828.879136-1-mark.rutland@arm.com>

From: Mark Rutland
> Sent: 09 January 2023 13:58
> 
> This series adds a new DYNAMIC_FTRACE_WITH_CALL_OPS mechanism, and
> enables support for this on arm64. This significantly reduces the
> overhead of tracing when a callsite/tracee has a single associated
> tracer, avoids a number of issues that make it undesireably and
> infeasible to use dynamically-allocated trampolines (e.g. branch range
> limitations), and makes it possible to implement support for
> DYNAMIC_FTRACE_WITH_DIRECT_CALLS in future.
> 
> The main idea is to give each ftrace callsite an associated pointer to
> an ftrace_ops. The architecture's ftrace_caller trampoline can recover
> the ops pointer and invoke ops->func from this without needing to use
> ftrace_ops_list_func, which has to iterate through all registered ops.
> 
> To do this, we use -fpatchable-function-entry=M,N, there N NOPs are
> placed before the function entry point...

Doesn't this bump the minimum gcc version up to something like 9.0 ?

How does it interact with the 'CFI stuff' that also uses the same area?

	David

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)


WARNING: multiple messages have this Message-ID (diff)
From: David Laight <David.Laight@ACULAB.COM>
To: 'Mark Rutland' <mark.rutland@arm.com>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>
Cc: "catalin.marinas@arm.com" <catalin.marinas@arm.com>,
	"lenb@kernel.org" <lenb@kernel.org>,
	"linux-acpi@vger.kernel.org" <linux-acpi@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"mhiramat@kernel.org" <mhiramat@kernel.org>,
	"ndesaulniers@google.com" <ndesaulniers@google.com>,
	"ojeda@kernel.org" <ojeda@kernel.org>,
	"peterz@infradead.org" <peterz@infradead.org>,
	"rafael.j.wysocki@intel.com" <rafael.j.wysocki@intel.com>,
	"revest@chromium.org" <revest@chromium.org>,
	"robert.moore@intel.com" <robert.moore@intel.com>,
	"rostedt@goodmis.org" <rostedt@goodmis.org>,
	"will@kernel.org" <will@kernel.org>
Subject: RE: [PATCH 0/8] arm64/ftrace: Add support for DYNAMIC_FTRACE_WITH_CALL_OPS
Date: Tue, 10 Jan 2023 08:55:58 +0000	[thread overview]
Message-ID: <34e0144b19e149d99719a5ffc834f228@AcuMS.aculab.com> (raw)
In-Reply-To: <20230109135828.879136-1-mark.rutland@arm.com>

From: Mark Rutland
> Sent: 09 January 2023 13:58
> 
> This series adds a new DYNAMIC_FTRACE_WITH_CALL_OPS mechanism, and
> enables support for this on arm64. This significantly reduces the
> overhead of tracing when a callsite/tracee has a single associated
> tracer, avoids a number of issues that make it undesireably and
> infeasible to use dynamically-allocated trampolines (e.g. branch range
> limitations), and makes it possible to implement support for
> DYNAMIC_FTRACE_WITH_DIRECT_CALLS in future.
> 
> The main idea is to give each ftrace callsite an associated pointer to
> an ftrace_ops. The architecture's ftrace_caller trampoline can recover
> the ops pointer and invoke ops->func from this without needing to use
> ftrace_ops_list_func, which has to iterate through all registered ops.
> 
> To do this, we use -fpatchable-function-entry=M,N, there N NOPs are
> placed before the function entry point...

Doesn't this bump the minimum gcc version up to something like 9.0 ?

How does it interact with the 'CFI stuff' that also uses the same area?

	David

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)


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  parent reply	other threads:[~2023-01-10  9:00 UTC|newest]

Thread overview: 56+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-01-09 13:58 [PATCH 0/8] arm64/ftrace: Add support for DYNAMIC_FTRACE_WITH_CALL_OPS Mark Rutland
2023-01-09 13:58 ` Mark Rutland
2023-01-09 13:58 ` [PATCH 1/8] Compiler attributes: GCC function alignment workarounds Mark Rutland
2023-01-09 13:58   ` Mark Rutland
2023-01-09 14:43   ` Miguel Ojeda
2023-01-09 14:43     ` Miguel Ojeda
2023-01-09 17:06     ` Mark Rutland
2023-01-09 17:06       ` Mark Rutland
2023-01-09 22:35       ` Miguel Ojeda
2023-01-09 22:35         ` Miguel Ojeda
2023-01-11 18:27     ` Mark Rutland
2023-01-11 18:27       ` Mark Rutland
2023-01-12 11:38       ` Mark Rutland
2023-01-12 11:38         ` Mark Rutland
2023-01-13 12:49         ` Mark Rutland
2023-01-13 12:49           ` Mark Rutland
2023-01-15 21:32           ` Miguel Ojeda
2023-01-15 21:32             ` Miguel Ojeda
2023-01-09 13:58 ` [PATCH 2/8] ACPI: Don't build ACPICA with '-Os' Mark Rutland
2023-01-09 13:58   ` Mark Rutland
2023-01-09 18:30   ` kernel test robot
2023-01-10 15:40     ` Mark Rutland
2023-01-10 13:45   ` Rafael J. Wysocki
2023-01-10 13:45     ` Rafael J. Wysocki
2023-01-09 13:58 ` [PATCH 3/8] arm64: Extend support for CONFIG_FUNCTION_ALIGNMENT Mark Rutland
2023-01-09 13:58   ` Mark Rutland
2023-01-10 20:35   ` Peter Zijlstra
2023-01-10 20:35     ` Peter Zijlstra
2023-01-10 20:43     ` Will Deacon
2023-01-10 20:43       ` Will Deacon
2023-01-11 11:39       ` Mark Rutland
2023-01-11 11:39         ` Mark Rutland
2023-01-11 11:36     ` Mark Rutland
2023-01-11 11:36       ` Mark Rutland
2023-01-09 13:58 ` [PATCH 4/8] ftrace: Add DYNAMIC_FTRACE_WITH_CALL_OPS Mark Rutland
2023-01-09 13:58   ` Mark Rutland
2023-01-09 17:39   ` kernel test robot
2023-01-09 19:10   ` kernel test robot
2023-01-12  6:48   ` Li Huafei
2023-01-12  6:48     ` Li Huafei
2023-01-12 11:00     ` Mark Rutland
2023-01-12 11:00       ` Mark Rutland
2023-01-13  1:15       ` Li Huafei
2023-01-13  1:15         ` Li Huafei
2023-01-09 13:58 ` [PATCH 5/8] arm64: insn: Add helpers for BTI Mark Rutland
2023-01-09 13:58   ` Mark Rutland
2023-01-09 13:58 ` [PATCH 6/8] arm64: patching: Add aarch64_insn_write_literal_u64() Mark Rutland
2023-01-09 13:58   ` Mark Rutland
2023-01-09 13:58 ` [PATCH 7/8] arm64: ftrace: Update stale comment Mark Rutland
2023-01-09 13:58   ` Mark Rutland
2023-01-09 13:58 ` [PATCH 8/8] arm64: Implement HAVE_DYNAMIC_FTRACE_WITH_CALL_OPS Mark Rutland
2023-01-09 13:58   ` Mark Rutland
2023-01-10  8:55 ` David Laight [this message]
2023-01-10  8:55   ` [PATCH 0/8] arm64/ftrace: Add support for DYNAMIC_FTRACE_WITH_CALL_OPS David Laight
2023-01-10 10:31   ` Mark Rutland
2023-01-10 10:31     ` Mark Rutland

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