From: Peter Zijlstra <peterz@infradead.org>
To: Indu Bhagat <indu.bhagat@oracle.com>
Cc: linux-toolchains@vger.kernel.org, daandemeyer@meta.com,
andrii@kernel.org, rostedt@goodmis.org, kris.van.hees@oracle.com,
elena.zannoni@oracle.com, nick.alcock@oracle.com
Subject: Re: [POC 3/5] sframe: add new SFrame library
Date: Tue, 2 May 2023 11:09:50 +0200 [thread overview]
Message-ID: <20230502090950.GI1597476@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20230501200410.3973453-4-indu.bhagat@oracle.com>
On Mon, May 01, 2023 at 01:04:08PM -0700, Indu Bhagat wrote:
> +struct sframe_header
> +{
> + struct sframe_preamble preamble;
> + /* Information about the arch (endianness) and ABI. */
> + uint8_t abi_arch;
> + /*
> + * Offset for the Frame Pointer (FP) from CFA may be fixed for some
> + * ABIs (e.g, in AMD64 when -fno-omit-frame-pointer is used). When fixed,
> + * this field specifies the fixed stack frame offset and the individual
> + * FREs do not need to track it. When not fixed, it is set to
> + * SFRAME_CFA_FIXED_FP_INVALID, and the individual FREs may provide
> + * the applicable stack frame offset, if any.
> + */
> + int8_t cfa_fixed_fp_offset;
> + /*
> + * Offset for the Return Address from CFA is fixed for some ABIs
> + * (e.g., AMD64 has it as CFA-8). When fixed, the header specifies the
> + * fixed stack frame offset and the individual FREs do not track it. When
> + * not fixed, it is set to SFRAME_CFA_FIXED_RA_INVALID, and individual
> + * FREs provide the applicable stack frame offset, if any.
> + */
> + int8_t cfa_fixed_ra_offset;
> + /*
> + * Number of bytes making up the auxiliary header, if any.
> + * Some ABI/arch, in the future, may use this space for extending the
> + * information in SFrame header. Auxiliary header is contained in
> + * bytes sequentially following the sframe_header.
> + */
> + uint8_t auxhdr_len;
> + /* Number of SFrame FDEs in this SFrame section. */
> + uint32_t num_fdes;
> + /* Number of SFrame Frame Row Entries. */
> + uint32_t num_fres;
> + /* Number of bytes in the SFrame Frame Row Entry section. */
> + uint32_t fre_len;
> + /* Offset of SFrame Function Descriptor Entry section. */
> + uint32_t fdeoff;
> + /* Offset of SFrame Frame Row Entry section. */
> + uint32_t freoff;
> +} __packed;
So I know there's people that hate hard on tail comments, but personally
I can't read the above, something like:
/*
* Number of bytes making up the auxiliary header, if any.
* Some ABI/arch, in the future, may use this space for extending the
* information in SFrame header. Auxiliary header is contained in
* bytes sequentially following the sframe_header.
*/
uint8_t auxhdr_len;
uint32_t num_fdes; /* Number of SFrame FDEs in this SFrame section. */
uint32_t num_fres; /* Number of SFrame Frame Row Entries. */
uint32_t fre_len; /* Number of bytes in the SFrame Frame Row Entry section. */
uint32_t fdeoff; /* Offset of SFrame Function Descriptor Entry section. */
uint32_t freoff; /* Offset of SFrame Frame Row Entry section. */
Is far more readable (but yes, busts the line length a little).
An alternative form might be:
/*
* @auxhdr_len: Number of bytes making up the auxiliary header, if any.
* Some ABI/arch, in the future, may use this space for extending the
* information in SFrame header. Auxiliary header is contained in
* bytes sequentially following the sframe_header.
* @num_fdes: Number of SFrame FDEs in this SFrame section.
* @num_fres: Number of SFrame Frame Row Entries.
* @fre_len: Number of bytes in the SFrame Frame Row Entry section.
* @fdeoff: Offset of SFrame Function Descriptor Entry section.
* @freoff: Offset of SFrame Frame Row Entry section.
*/
uint8_t auxhdr_len;
uint32_t num_fdes;
uint32_t num_fres;
uint32_t fre_len;
uint32_t fdeoff;
uint32_t freoff;
next prev parent reply other threads:[~2023-05-02 9:10 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-01 20:04 [POC 0/5] SFrame based stack tracer for user space in the kernel Indu Bhagat
2023-05-01 20:04 ` [POC 1/5] Kconfig: x86: Add new config options for userspace unwinder Indu Bhagat
2023-05-01 20:04 ` [POC 2/5] task_struct : add additional member for sframe state Indu Bhagat
2023-05-01 20:04 ` [POC 3/5] sframe: add new SFrame library Indu Bhagat
2023-05-01 22:40 ` Steven Rostedt
2023-05-02 5:07 ` Indu Bhagat
2023-05-02 8:46 ` Peter Zijlstra
2023-05-02 9:09 ` Peter Zijlstra [this message]
2023-05-02 9:20 ` Peter Zijlstra
2023-05-02 9:28 ` Peter Zijlstra
2023-05-02 9:30 ` Peter Zijlstra
2023-05-03 6:03 ` Indu Bhagat
2023-05-02 10:31 ` Peter Zijlstra
2023-05-02 10:41 ` Peter Zijlstra
2023-05-02 15:22 ` Steven Rostedt
2023-05-01 20:04 ` [POC 4/5] sframe: add an SFrame format stack tracer Indu Bhagat
2023-05-01 23:00 ` Steven Rostedt
2023-05-02 6:16 ` Indu Bhagat
2023-05-02 8:53 ` Peter Zijlstra
2023-05-02 9:04 ` Peter Zijlstra
2023-05-01 20:04 ` [POC 5/5] x86_64: invoke SFrame based stack tracer for user space Indu Bhagat
2023-05-01 23:11 ` Steven Rostedt
2023-05-02 10:53 ` Peter Zijlstra
2023-05-02 15:27 ` Steven Rostedt
2023-05-16 17:25 ` Andrii Nakryiko
2023-05-16 17:38 ` Steven Rostedt
2023-05-16 17:51 ` Andrii Nakryiko
2024-03-13 14:37 ` Tatsuyuki Ishi
2024-03-13 14:52 ` Steven Rostedt
2024-03-13 14:58 ` Tatsuyuki Ishi
2024-03-13 15:04 ` Steven Rostedt
2023-05-01 22:15 ` [POC 0/5] SFrame based stack tracer for user space in the kernel Steven Rostedt
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