From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 55CB61B85CA; Thu, 30 Jan 2025 09:53:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=13.77.154.182 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738230806; cv=none; b=LEJxZeD6cXnzfm5IZybN7OXKSj09qe0U+o6FIUU6QmTRcY4d7Ml+xx6J1LZ95NW1v2CQgglsjIPLYIhLGpyaYhN9uFNTyHfMNz1c4y53LaozieM68IQuTNE0nhogLFOnz/89oYnp3FXRYJ7maCu88ZSu9nPWazkE5SjJ8AoJ/J8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738230806; c=relaxed/simple; bh=vyvvFWCJPiszGlA9jXb+sS9KrOxg+WCmzPAQr9OxoRc=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=u7XpmF7uz/rrF2sLOMCy+r6YpkyD4VVQCsilbDpZlt4QtRilvr0VdBvTNlZNRKa+MHqpGzhQ6nzSuxh8nVR51ez8QXPfVpwZVyRQ+sw/13q1klAckNAI/F20qarZXPwWLijXDP43ZXayZ0z1tbx4wW/4DzqcYTCNWVEIbW6TpRw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.microsoft.com; spf=pass smtp.mailfrom=linux.microsoft.com; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b=gtzsMnkr; arc=none smtp.client-ip=13.77.154.182 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.microsoft.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.microsoft.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b="gtzsMnkr" Received: from [10.156.205.88] (unknown [167.220.238.88]) by linux.microsoft.com (Postfix) with ESMTPSA id 6FE8C2109CD7; Thu, 30 Jan 2025 01:53:20 -0800 (PST) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 6FE8C2109CD7 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1738230803; bh=x973D1YtTSuerbgIqP0nPMvsl0lyHBrerW2rQqaj1Jw=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=gtzsMnkrbY7Gw7uExDQbFAF48tutey2piJQfp8+YNhPN6rruZi0S1Y9EM6LLv4nFr gjfGLklVuqKn+ZzEe/uxv9vbIuohp8YpYQWKg0Wt7kpws3mcMIY9CFbg7lr5WYr1LO WCuYnHSDidOGwNhKVJgKmd8HBAb9uscz2bXQRPLU= Message-ID: <3be32c6e-0041-4087-953b-06356b7a3d65@linux.microsoft.com> Date: Thu, 30 Jan 2025 15:23:19 +0530 Precedence: bulk X-Mailing-List: live-patching@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 3/8] unwind: add sframe v2 header To: Weinan Liu , Josh Poimboeuf , Steven Rostedt , Indu Bhagat , Peter Zijlstra Cc: Mark Rutland , roman.gushchin@linux.dev, Will Deacon , Ian Rogers , linux-toolchains@vger.kernel.org, linux-kernel@vger.kernel.org, live-patching@vger.kernel.org, joe.lawrence@redhat.com, linux-arm-kernel@lists.infradead.org References: <20250127213310.2496133-1-wnliu@google.com> <20250127213310.2496133-4-wnliu@google.com> Content-Language: en-US From: Prasanna Kumar T S M In-Reply-To: <20250127213310.2496133-4-wnliu@google.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 28-01-2025 03:03, Weinan Liu wrote: > Add sframe header so that we know how to access the sframe section > generated by compilers. > > This is the sframe header file borrowed from the patchset [1] > Josh Poimboeuf according to sframe v2 spec [2]. > > [1]: https://lore.kernel.org/lkml/42c0a99236af65c09c8182e260af7bcf5aa1e158.1730150953.git.jpoimboe@kernel.org/ > [2]: https://sourceware.org/binutils/docs/sframe-spec.html > > Signed-off-by: Weinan Liu > --- > kernel/sframe.h | 215 ++++++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 215 insertions(+) > create mode 100644 kernel/sframe.h > > diff --git a/kernel/sframe.h b/kernel/sframe.h > new file mode 100644 > index 000000000000..11b9be7ad82e > --- /dev/null > +++ b/kernel/sframe.h > @@ -0,0 +1,215 @@ > +/* SPDX-License-Identifier: GPL-2.0-or-later */ > +/* > + * Copyright (C) 2023, Oracle and/or its affiliates. > + * > + * This file contains definitions for the SFrame stack tracing format, which is > + * documented at https://sourceware.org/binutils/docs > + */ > +#ifndef _SFRAME_H > +#define _SFRAME_H > + > +#include > + > +#define SFRAME_VERSION_1 1 > +#define SFRAME_VERSION_2 2 > +#define SFRAME_MAGIC 0xdee2 > + > +/* Function Descriptor Entries are sorted on PC. */ > +#define SFRAME_F_FDE_SORTED 0x1 > +/* Frame-pointer based stack tracing. Defined, but not set. */ > +#define SFRAME_F_FRAME_POINTER 0x2 > + > +#define SFRAME_CFA_FIXED_FP_INVALID 0 > +#define SFRAME_CFA_FIXED_RA_INVALID 0 > + > +/* Supported ABIs/Arch. */ > +#define SFRAME_ABI_AARCH64_ENDIAN_BIG 1 /* AARCH64 big endian. */ > +#define SFRAME_ABI_AARCH64_ENDIAN_LITTLE 2 /* AARCH64 little endian. */ > +#define SFRAME_ABI_AMD64_ENDIAN_LITTLE 3 /* AMD64 little endian. */ > + > +/* SFrame FRE types. */ > +#define SFRAME_FRE_TYPE_ADDR1 0 > +#define SFRAME_FRE_TYPE_ADDR2 1 > +#define SFRAME_FRE_TYPE_ADDR4 2 > + > +/* > + * SFrame Function Descriptor Entry types. > + * > + * The SFrame format has two possible representations for functions. The > + * choice of which type to use is made according to the instruction patterns > + * in the relevant program stub. > + */ > + > +/* Unwinders perform a (PC >= FRE_START_ADDR) to look up a matching FRE. */ > +#define SFRAME_FDE_TYPE_PCINC 0 > +/* > + * Unwinders perform a (PC & FRE_START_ADDR_AS_MASK >= FRE_START_ADDR_AS_MASK) > + * to look up a matching FRE. Typical usecases are pltN entries, trampolines > + * etc. > + */ > +#define SFRAME_FDE_TYPE_PCMASK 1 > + > +/** > + * struct sframe_preamble - SFrame Preamble. > + * @magic: Magic number (SFRAME_MAGIC). > + * @version: Format version number (SFRAME_VERSION). > + * @flags: Various flags. > + */ > +struct sframe_preamble { > + u16 magic; > + u8 version; > + u8 flags; > +} __packed; > + > +/** > + * struct sframe_header - SFrame Header. > + * @preamble: SFrame preamble. > + * @abi_arch: Identify the arch (including endianness) and ABI. > + * @cfa_fixed_fp_offset: 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. > + * @cfa_fixed_ra_offset: Offset for the Return Address from CFA is fixed for > + * some ABIs. 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. > + * @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. > + * @fdes_off: Offset of SFrame Function Descriptor Entry section. > + * @fres_off: Offset of SFrame Frame Row Entry section. > + */ > +struct sframe_header { > + struct sframe_preamble preamble; > + u8 abi_arch; > + s8 cfa_fixed_fp_offset; > + s8 cfa_fixed_ra_offset; > + u8 auxhdr_len; > + u32 num_fdes; > + u32 num_fres; > + u32 fre_len; > + u32 fdes_off; > + u32 fres_off; > +} __packed; > + > +#define SFRAME_HDR_SIZE(sframe_hdr) \ > + ((sizeof(struct sframe_header) + (sframe_hdr).auxhdr_len)) > + > +/* Two possible keys for executable (instruction) pointers signing. */ > +#define SFRAME_AARCH64_PAUTH_KEY_A 0 /* Key A. */ > +#define SFRAME_AARCH64_PAUTH_KEY_B 1 /* Key B. */ > + > +/** > + * struct sframe_fde - SFrame Function Descriptor Entry. > + * @start_addr: Function start address. Encoded as a signed offset, > + * relative to the current FDE. > + * @size: Size of the function in bytes. > + * @fres_off: Offset of the first SFrame Frame Row Entry of the function, > + * relative to the beginning of the SFrame Frame Row Entry sub-section. > + * @fres_num: Number of frame row entries for the function. > + * @info: Additional information for deciphering the stack trace > + * information for the function. Contains information about SFrame FRE > + * type, SFrame FDE type, PAC authorization A/B key, etc. > + * @rep_size: Block size for SFRAME_FDE_TYPE_PCMASK > + * @padding: Unused > + */ > +struct sframe_fde { > + s32 start_addr; > + u32 size; > + u32 fres_off; > + u32 fres_num; > + u8 info; > + u8 rep_size; > + u16 padding; > +} __packed; > + > +/* > + * 'func_info' in SFrame FDE contains additional information for deciphering > + * the stack trace information for the function. In V1, the information is > + * organized as follows: > + * - 4-bits: Identify the FRE type used for the function. > + * - 1-bit: Identify the FDE type of the function - mask or inc. > + * - 1-bit: PAC authorization A/B key (aarch64). > + * - 2-bits: Unused. > + * --------------------------------------------------------------------- > + * | Unused | PAC auth A/B key (aarch64) | FDE type | FRE type | > + * | | Unused (amd64) | | | > + * --------------------------------------------------------------------- > + * 8 6 5 4 0 > + */ > + > +/* Note: Set PAC auth key to SFRAME_AARCH64_PAUTH_KEY_A by default. */ > +#define SFRAME_FUNC_INFO(fde_type, fre_enc_type) \ > + (((SFRAME_AARCH64_PAUTH_KEY_A & 0x1) << 5) | \ > + (((fde_type) & 0x1) << 4) | ((fre_enc_type) & 0xf)) > + > +#define SFRAME_FUNC_FRE_TYPE(data) ((data) & 0xf) > +#define SFRAME_FUNC_FDE_TYPE(data) (((data) >> 4) & 0x1) > +#define SFRAME_FUNC_PAUTH_KEY(data) (((data) >> 5) & 0x1) > + > +/* > + * Size of stack frame offsets in an SFrame Frame Row Entry. A single > + * SFrame FRE has all offsets of the same size. Offset size may vary > + * across frame row entries. > + */ > +#define SFRAME_FRE_OFFSET_1B 0 > +#define SFRAME_FRE_OFFSET_2B 1 > +#define SFRAME_FRE_OFFSET_4B 2 > + > +/* An SFrame Frame Row Entry can be SP or FP based. */ > +#define SFRAME_BASE_REG_FP 0 > +#define SFRAME_BASE_REG_SP 1 > + > +/* > + * The index at which a specific offset is presented in the variable length > + * bytes of an FRE. > + */ > +#define SFRAME_FRE_CFA_OFFSET_IDX 0 > +/* > + * The RA stack offset, if present, will always be at index 1 in the variable > + * length bytes of the FRE. > + */ > +#define SFRAME_FRE_RA_OFFSET_IDX 1 > +/* > + * The FP stack offset may appear at offset 1 or 2, depending on the ABI as RA > + * may or may not be tracked. > + */ > +#define SFRAME_FRE_FP_OFFSET_IDX 2 > + > +/* > + * 'fre_info' in SFrame FRE contains information about: > + * - 1 bit: base reg for CFA > + * - 4 bits: Number of offsets (N). A value of up to 3 is allowed to track > + * all three of CFA, FP and RA (fixed implicit order). > + * - 2 bits: information about size of the offsets (S) in bytes. > + * Valid values are SFRAME_FRE_OFFSET_1B, SFRAME_FRE_OFFSET_2B, > + * SFRAME_FRE_OFFSET_4B > + * - 1 bit: Mangled RA state bit (aarch64 only). > + * --------------------------------------------------------------- > + * | Mangled-RA (aarch64) | Size of | Number of | base_reg | > + * | Unused (amd64) | offsets | offsets | | > + * --------------------------------------------------------------- > + * 8 7 5 1 0 > + */ > + > +/* Note: Set mangled_ra_p to zero by default. */ > +#define SFRAME_FRE_INFO(base_reg_id, offset_num, offset_size) \ > + (((0 & 0x1) << 7) | (((offset_size) & 0x3) << 5) | \ > + (((offset_num) & 0xf) << 1) | ((base_reg_id) & 0x1)) > + > +/* Set the mangled_ra_p bit as indicated. */ > +#define SFRAME_FRE_INFO_UPDATE_MANGLED_RA_P(mangled_ra_p, fre_info) \ > + ((((mangled_ra_p) & 0x1) << 7) | ((fre_info) & 0x7f)) > + > +#define SFRAME_FRE_CFA_BASE_REG_ID(data) ((data) & 0x1) > +#define SFRAME_FRE_OFFSET_COUNT(data) (((data) >> 1) & 0xf) > +#define SFRAME_FRE_OFFSET_SIZE(data) (((data) >> 5) & 0x3) > +#define SFRAME_FRE_MANGLED_RA_P(data) (((data) >> 7) & 0x1) > + > +#endif /* _SFRAME_H */ Looks good to me. Reviewed-by: Prasanna Kumar T S M .