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Wed, 19 Nov 2025 13:23:26 GMT Received: from smtpav02.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id A3D5720040; Wed, 19 Nov 2025 13:23:26 +0000 (GMT) Received: from smtpav02.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 177D52004F; Wed, 19 Nov 2025 13:23:26 +0000 (GMT) Received: from tuxmaker.boeblingen.de.ibm.com (unknown [9.152.85.9]) by smtpav02.fra02v.mail.ibm.com (Postfix) with ESMTP; Wed, 19 Nov 2025 13:23:26 +0000 (GMT) From: Jens Remus To: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, bpf@vger.kernel.org, x86@kernel.org, linux-mm@kvack.org, Steven Rostedt Cc: Jens Remus , Josh Poimboeuf , Masami Hiramatsu , Mathieu Desnoyers , Peter Zijlstra , Ingo Molnar , Jiri Olsa , Arnaldo Carvalho de Melo , Namhyung Kim , Thomas Gleixner , Andrii Nakryiko , Indu Bhagat , "Jose E. Marchesi" , Beau Belgrave , Linus Torvalds , Andrew Morton , Florian Weimer , Kees Cook , "Carlos O'Donell" , Sam James , Dylan Hatch , Borislav Petkov , Dave Hansen , David Hildenbrand , "H. Peter Anvin" , "Liam R. Howlett" , Lorenzo Stoakes , Michal Hocko , Mike Rapoport , Suren Baghdasaryan , Vlastimil Babka , Heiko Carstens , Vasily Gorbik , "Steven Rostedt (Google)" Subject: [PATCH v12 01/13] unwind_user/sframe: Add support for reading .sframe headers Date: Wed, 19 Nov 2025 14:23:11 +0100 Message-ID: <20251119132323.1281768-2-jremus@linux.ibm.com> X-Mailer: git-send-email 2.48.1 In-Reply-To: <20251119132323.1281768-1-jremus@linux.ibm.com> References: <20251119132323.1281768-1-jremus@linux.ibm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Authority-Analysis: v=2.4 cv=C/nkCAP+ c=1 sm=1 tr=0 ts=691dc4d4 cx=c_pps a=aDMHemPKRhS1OARIsFnwRA==:117 a=aDMHemPKRhS1OARIsFnwRA==:17 a=6UeiqGixMTsA:10 a=VkNPw1HP01LnGYTKEx00:22 a=VwQbUJbxAAAA:8 a=CCpqsmhAAAAA:8 a=7d_E57ReAAAA:8 a=JfrnYn6hAAAA:8 a=yPCof4ZbAAAA:8 a=mDV3o1hIAAAA:8 a=yMhMjlubAAAA:8 a=VnNF1IyMAAAA:8 a=Z4Rwk6OoAAAA:8 a=20KFwNOVAAAA:8 a=7mOBRU54AAAA:8 a=meVymXHHAAAA:8 a=Erb6gmh4r_fQ_4OwCTwA:9 a=gWTG3a1JFnwA:10 a=0rJyKvmL6cEA:10 a=ul9cdbp4aOFLsgKbc677:22 a=jhqOcbufqs7Y1TYCrUUU:22 a=1CNFftbPRP8L7MoqJWF3:22 a=HkZW87K1Qel5hWWM3VKY:22 a=wa9RWnbW_A1YIeRBVszw:22 a=2JgSa4NbpEOStq-L5dxp:22 X-Proofpoint-GUID: 4lR7OG504f9j9rDJ4S5TEL25Yk4fPGVT X-Proofpoint-ORIG-GUID: YpDsnFwENqs8JMW632VZHYv3EYn6OUrl X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUxMTE1MDAzMiBTYWx0ZWRfX3+0liteFPMk5 Sjplcl0KIn9TTlGiuaq8E9JkQVjr+SjwSuaH/gF2xUq6+EvCKfWnESZC4E8l95jsMASRklvwS/h WWjZailqE1sgFZoVk2ZCAeSzp6x+jEcz+2Q+Cfx/F7pUDgfbuSDrlhKZmn2QfD8Z3yDFo44Wzoy uIKvYq5X5dlvJe+mJkxEre+UczB12k1KHlQkig7I+YFLVIDHqhD50E5ndxXBxcxHWeR1ToruhIR 20gaCfSP54wK63xTsrtDyiET9YR+297aZF5dsLnTrGI/QGFZKeQzMOjLexe+pq0yknBRgKbShV5 I8QRQ4wG17fKcRPTh8fgaC0rDH90tGmsVIEWkfSVf/xzItkYMorZDx8Wk+n7EQKnJRiDgA3PoZz nRuQ0ouONI0wNQYTK3CI4BuvEeFUyg== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1121,Hydra:6.1.9,FMLib:17.12.100.49 definitions=2025-11-19_04,2025-11-18_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 priorityscore=1501 spamscore=0 impostorscore=0 bulkscore=0 malwarescore=0 suspectscore=0 clxscore=1015 lowpriorityscore=0 adultscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2510240000 definitions=main-2511150032 X-Rspamd-Queue-Id: CABDEA0003 X-Stat-Signature: qmabawmfp1jea4jx3hrfospet33wtkyq X-Rspamd-Server: rspam02 X-Rspam-User: X-HE-Tag: 1763558688-243599 X-HE-Meta: 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 YI4tgW2s 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: From: Josh Poimboeuf In preparation for unwinding user space stacks with sframe, add basic sframe compile infrastructure and support for reading the .sframe section header. sframe_add_section() reads the header and unconditionally returns an error, so it's not very useful yet. A subsequent patch will improve that. Link: https://lore.kernel.org/all/f27e8463783febfa0dabb0432a3dd6be8ad98412.1737511963.git.jpoimboe@kernel.org/ [ Jens Remus: Add support for PC-relative FDE function start address. Cleanup includes and indentation. ] Cc: Masami Hiramatsu Cc: Mathieu Desnoyers Cc: Peter Zijlstra Cc: Ingo Molnar Cc: Jiri Olsa Cc: Arnaldo Carvalho de Melo Cc: Namhyung Kim Cc: Thomas Gleixner Cc: Andrii Nakryiko Cc: Indu Bhagat Cc: "Jose E. Marchesi" Cc: Beau Belgrave Cc: Jens Remus Cc: Linus Torvalds Cc: Andrew Morton Cc: Florian Weimer Cc: Sam James Cc: Kees Cook Cc: "Carlos O'Donell" Signed-off-by: Josh Poimboeuf Signed-off-by: Steven Rostedt (Google) Signed-off-by: Jens Remus --- Notes (jremus): Changes in v12: - Move include of linux/unwind_user_types.h to "unwind_user/sframe: Add support for reading .sframe contents". - Move include of linux/mm_types.h and variable sframe_mt to "unwind_user/sframe: Store sframe section data in per-mm maple tree". - Fix indentation of struct sframe_fde field padding. Changes in v11: - Support for SFrame V2 PC-relative FDE function start address. MAINTAINERS | 1 + arch/Kconfig | 3 + include/linux/sframe.h | 37 +++++++++++ kernel/unwind/Makefile | 3 +- kernel/unwind/sframe.c | 136 +++++++++++++++++++++++++++++++++++++++++ kernel/unwind/sframe.h | 72 ++++++++++++++++++++++ 6 files changed, 251 insertions(+), 1 deletion(-) create mode 100644 include/linux/sframe.h create mode 100644 kernel/unwind/sframe.c create mode 100644 kernel/unwind/sframe.h diff --git a/MAINTAINERS b/MAINTAINERS index b0569f6fc48f..eb65bf7bd10d 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -26811,6 +26811,7 @@ USERSPACE STACK UNWINDING M: Josh Poimboeuf M: Steven Rostedt S: Maintained +F: include/linux/sframe.h F: include/linux/unwind*.h F: kernel/unwind/ diff --git a/arch/Kconfig b/arch/Kconfig index 61130b88964b..cdb0e72773be 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -489,6 +489,9 @@ config HAVE_UNWIND_USER_FP bool select UNWIND_USER +config HAVE_UNWIND_USER_SFRAME + bool + config HAVE_PERF_REGS bool help diff --git a/include/linux/sframe.h b/include/linux/sframe.h new file mode 100644 index 000000000000..0642595534f9 --- /dev/null +++ b/include/linux/sframe.h @@ -0,0 +1,37 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _LINUX_SFRAME_H +#define _LINUX_SFRAME_H + +#ifdef CONFIG_HAVE_UNWIND_USER_SFRAME + +struct sframe_section { + unsigned long sframe_start; + unsigned long sframe_end; + unsigned long text_start; + unsigned long text_end; + + unsigned long fdes_start; + unsigned long fres_start; + unsigned long fres_end; + unsigned int num_fdes; + + signed char ra_off; + signed char fp_off; +}; + +extern int sframe_add_section(unsigned long sframe_start, unsigned long sframe_end, + unsigned long text_start, unsigned long text_end); +extern int sframe_remove_section(unsigned long sframe_addr); + +#else /* !CONFIG_HAVE_UNWIND_USER_SFRAME */ + +static inline int sframe_add_section(unsigned long sframe_start, unsigned long sframe_end, + unsigned long text_start, unsigned long text_end) +{ + return -ENOSYS; +} +static inline int sframe_remove_section(unsigned long sframe_addr) { return -ENOSYS; } + +#endif /* CONFIG_HAVE_UNWIND_USER_SFRAME */ + +#endif /* _LINUX_SFRAME_H */ diff --git a/kernel/unwind/Makefile b/kernel/unwind/Makefile index eae37bea54fd..146038165865 100644 --- a/kernel/unwind/Makefile +++ b/kernel/unwind/Makefile @@ -1 +1,2 @@ - obj-$(CONFIG_UNWIND_USER) += user.o deferred.o + obj-$(CONFIG_UNWIND_USER) += user.o deferred.o + obj-$(CONFIG_HAVE_UNWIND_USER_SFRAME) += sframe.o diff --git a/kernel/unwind/sframe.c b/kernel/unwind/sframe.c new file mode 100644 index 000000000000..26bb16f76a8d --- /dev/null +++ b/kernel/unwind/sframe.c @@ -0,0 +1,136 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Userspace sframe access functions + */ + +#define pr_fmt(fmt) "sframe: " fmt + +#include +#include +#include +#include +#include +#include +#include +#include + +#include "sframe.h" + +#define dbg(fmt, ...) \ + pr_debug("%s (%d): " fmt, current->comm, current->pid, ##__VA_ARGS__) + +static void free_section(struct sframe_section *sec) +{ + kfree(sec); +} + +static int sframe_read_header(struct sframe_section *sec) +{ + unsigned long header_end, fdes_start, fdes_end, fres_start, fres_end; + struct sframe_header shdr; + unsigned int num_fdes; + + if (copy_from_user(&shdr, (void __user *)sec->sframe_start, sizeof(shdr))) { + dbg("header usercopy failed\n"); + return -EFAULT; + } + + if (shdr.preamble.magic != SFRAME_MAGIC || + shdr.preamble.version != SFRAME_VERSION_2 || + !(shdr.preamble.flags & SFRAME_F_FDE_SORTED) || + !(shdr.preamble.flags & SFRAME_F_FDE_FUNC_START_PCREL) || + shdr.auxhdr_len) { + dbg("bad/unsupported sframe header\n"); + return -EINVAL; + } + + if (!shdr.num_fdes || !shdr.num_fres) { + dbg("no fde/fre entries\n"); + return -EINVAL; + } + + header_end = sec->sframe_start + SFRAME_HEADER_SIZE(shdr); + if (header_end >= sec->sframe_end) { + dbg("header doesn't fit in section\n"); + return -EINVAL; + } + + num_fdes = shdr.num_fdes; + fdes_start = header_end + shdr.fdes_off; + fdes_end = fdes_start + (num_fdes * sizeof(struct sframe_fde)); + + fres_start = header_end + shdr.fres_off; + fres_end = fres_start + shdr.fre_len; + + if (fres_start < fdes_end || fres_end > sec->sframe_end) { + dbg("inconsistent fde/fre offsets\n"); + return -EINVAL; + } + + sec->num_fdes = num_fdes; + sec->fdes_start = fdes_start; + sec->fres_start = fres_start; + sec->fres_end = fres_end; + + sec->ra_off = shdr.cfa_fixed_ra_offset; + sec->fp_off = shdr.cfa_fixed_fp_offset; + + return 0; +} + +int sframe_add_section(unsigned long sframe_start, unsigned long sframe_end, + unsigned long text_start, unsigned long text_end) +{ + struct vm_area_struct *sframe_vma, *text_vma; + struct mm_struct *mm = current->mm; + struct sframe_section *sec; + int ret; + + if (!sframe_start || !sframe_end || !text_start || !text_end) { + dbg("zero-length sframe/text address\n"); + return -EINVAL; + } + + scoped_guard(mmap_read_lock, mm) { + sframe_vma = vma_lookup(mm, sframe_start); + if (!sframe_vma || sframe_end > sframe_vma->vm_end) { + dbg("bad sframe address (0x%lx - 0x%lx)\n", + sframe_start, sframe_end); + return -EINVAL; + } + + text_vma = vma_lookup(mm, text_start); + if (!text_vma || + !(text_vma->vm_flags & VM_EXEC) || + text_end > text_vma->vm_end) { + dbg("bad text address (0x%lx - 0x%lx)\n", + text_start, text_end); + return -EINVAL; + } + } + + sec = kzalloc(sizeof(*sec), GFP_KERNEL); + if (!sec) + return -ENOMEM; + + sec->sframe_start = sframe_start; + sec->sframe_end = sframe_end; + sec->text_start = text_start; + sec->text_end = text_end; + + ret = sframe_read_header(sec); + if (ret) + goto err_free; + + /* TODO nowhere to store it yet - just free it and return an error */ + ret = -ENOSYS; + +err_free: + free_section(sec); + return ret; +} + +int sframe_remove_section(unsigned long sframe_start) +{ + return -ENOSYS; +} diff --git a/kernel/unwind/sframe.h b/kernel/unwind/sframe.h new file mode 100644 index 000000000000..69ce0d5b9694 --- /dev/null +++ b/kernel/unwind/sframe.h @@ -0,0 +1,72 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +/* + * From https://www.sourceware.org/binutils/docs/sframe-spec.html + */ +#ifndef _SFRAME_H +#define _SFRAME_H + +#include + +#define SFRAME_VERSION_1 1 +#define SFRAME_VERSION_2 2 +#define SFRAME_MAGIC 0xdee2 + +#define SFRAME_F_FDE_SORTED 0x1 +#define SFRAME_F_FRAME_POINTER 0x2 +#define SFRAME_F_FDE_FUNC_START_PCREL 0x4 + +#define SFRAME_ABI_AARCH64_ENDIAN_BIG 1 +#define SFRAME_ABI_AARCH64_ENDIAN_LITTLE 2 +#define SFRAME_ABI_AMD64_ENDIAN_LITTLE 3 + +#define SFRAME_FDE_TYPE_PCINC 0 +#define SFRAME_FDE_TYPE_PCMASK 1 + +struct sframe_preamble { + u16 magic; + u8 version; + u8 flags; +} __packed; + +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_HEADER_SIZE(header) \ + ((sizeof(struct sframe_header) + header.auxhdr_len)) + +#define SFRAME_AARCH64_PAUTH_KEY_A 0 +#define SFRAME_AARCH64_PAUTH_KEY_B 1 + +struct sframe_fde { + s32 start_addr; + u32 func_size; + u32 fres_off; + u32 fres_num; + u8 info; + u8 rep_size; + u16 padding; +} __packed; + +#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) + +#define SFRAME_BASE_REG_FP 0 +#define SFRAME_BASE_REG_SP 1 + +#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 */ -- 2.48.1