linux-kernel - [PATCH v2 5/6] arm64/module, unwind: Add sframe support for modules.

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Message-ID: <20250904223850.884188-6-dylanbhatch@google.com>
Date: Thu,  4 Sep 2025 22:38:49 +0000
From: Dylan Hatch <dylanbhatch@...gle.com>
To: Josh Poimboeuf <jpoimboe@...nel.org>, Steven Rostedt <rostedt@...dmis.org>, 
	Indu Bhagat <indu.bhagat@...cle.com>, Peter Zijlstra <peterz@...radead.org>, 
	Will Deacon <will@...nel.org>, Catalin Marinas <catalin.marinas@....com>, 
	Jiri Kosina <jikos@...nel.org>
Cc: Dylan Hatch <dylanbhatch@...gle.com>, Roman Gushchin <roman.gushchin@...ux.dev>, 
	Weinan Liu <wnliu@...gle.com>, Mark Rutland <mark.rutland@....com>, Ian Rogers <irogers@...gle.com>, 
	linux-toolchains@...r.kernel.org, linux-kernel@...r.kernel.org, 
	live-patching@...r.kernel.org, joe.lawrence@...hat.com, 
	Puranjay Mohan <puranjay@...nel.org>, Song Liu <song@...nel.org>
Subject: [PATCH v2 5/6] arm64/module, unwind: Add sframe support for modules.

From: Weinan Liu <wnliu@...gle.com>

Add sframe table to mod_arch_specific and support sframe unwind when
.sframe section can be found on incoming modules.

Signed-off-by: Dylan Hatch <dylanbhatch@...gle.com>
Signed-off-by: Weinan Liu <wnliu@...gle.com>
---
 arch/arm64/include/asm/module.h |  6 ++++++
 arch/arm64/kernel/module.c      |  5 +++++
 include/linux/sframe_lookup.h   |  2 ++
 kernel/sframe_lookup.c          | 38 ++++++++++++++++++++++++++++++++-
 4 files changed, 50 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/module.h b/arch/arm64/include/asm/module.h
index 79550b22ba19..e3781fcdc620 100644
--- a/arch/arm64/include/asm/module.h
+++ b/arch/arm64/include/asm/module.h
@@ -6,6 +6,7 @@
 #define __ASM_MODULE_H
 
 #include <asm-generic/module.h>
+#include <linux/sframe_lookup.h>
 
 struct mod_plt_sec {
 	int			plt_shndx;
@@ -17,6 +18,11 @@ struct mod_arch_specific {
 	struct mod_plt_sec	core;
 	struct mod_plt_sec	init;
 
+#ifdef CONFIG_SFRAME_UNWINDER
+	struct sframe_table sftbl;
+	bool sframe_init;
+#endif
+
 	/* for CONFIG_DYNAMIC_FTRACE */
 	struct plt_entry	*ftrace_trampolines;
 };
diff --git a/arch/arm64/kernel/module.c b/arch/arm64/kernel/module.c
index 40148d2725ce..d0adeb4cf63d 100644
--- a/arch/arm64/kernel/module.c
+++ b/arch/arm64/kernel/module.c
@@ -18,6 +18,7 @@
 #include <linux/moduleloader.h>
 #include <linux/random.h>
 #include <linux/scs.h>
+#include <linux/sframe_lookup.h>
 
 #include <asm/alternative.h>
 #include <asm/insn.h>
@@ -491,5 +492,9 @@ int module_finalize(const Elf_Ehdr *hdr,
 		}
 	}
 
+	s = find_section(hdr, sechdrs, ".sframe");
+	if (s)
+		sframe_module_init(me, (void *)s->sh_addr, s->sh_size);
+
 	return module_init_ftrace_plt(hdr, sechdrs, me);
 }
diff --git a/include/linux/sframe_lookup.h b/include/linux/sframe_lookup.h
index 1c26cf1f38d4..f84c1f41a421 100644
--- a/include/linux/sframe_lookup.h
+++ b/include/linux/sframe_lookup.h
@@ -31,9 +31,11 @@ struct sframe_table {
 
 #ifdef CONFIG_SFRAME_UNWINDER
 void init_sframe_table(void);
+void sframe_module_init(struct module *mod, void *_sframe, size_t _sframe_size);
 int sframe_find_pc(unsigned long pc, struct sframe_ip_entry *entry);
 #else
 static inline void init_sframe_table(void) {}
+static inline void sframe_module_init(struct module *mod, void *_sframe, size_t _sframe_size) {}
 static inline int sframe_find_pc(unsigned long pc, struct sframe_ip_entry *entry)
 {
 	return -EINVAL;
diff --git a/kernel/sframe_lookup.c b/kernel/sframe_lookup.c
index 51cd24a75956..c87a94f01891 100644
--- a/kernel/sframe_lookup.c
+++ b/kernel/sframe_lookup.c
@@ -156,10 +156,20 @@ int sframe_find_pc(unsigned long pc, struct sframe_ip_entry *entry)
 	struct sframe_table *sftbl_p = &sftbl;
 	int err;
 
-	if (!sframe_init)
+	if (!entry || !sframe_init)
 		return -EINVAL;
 
 	memset(entry, 0, sizeof(*entry));
+
+	if (!is_ksym_addr(pc)) {
+		struct module *mod;
+
+		mod = __module_address(pc);
+		if (!mod || !mod->arch.sframe_init)
+			return -EINVAL;
+		sftbl_p = &mod->arch.sftbl;
+	}
+
 	entry->ra_offset = sftbl_p->sfhdr_p->cfa_fixed_ra_offset;
 	entry->fp_offset = sftbl_p->sfhdr_p->cfa_fixed_fp_offset;
 
@@ -194,3 +204,29 @@ void __init init_sframe_table(void)
 		+ sftbl.sfhdr_p->fres_off;
 	sframe_init = true;
 }
+
+void sframe_module_init(struct module *mod, void *_sframe, size_t _sframe_size)
+{
+	size_t sframe_size = _sframe_size;
+	void *sframe_buf = _sframe;
+	struct sframe_table _sftbl;
+
+
+	if (sframe_size <= 0)
+		return;
+	_sftbl.sfhdr_p = sframe_buf;
+	if (!_sftbl.sfhdr_p || _sftbl.sfhdr_p->preamble.magic != SFRAME_MAGIC ||
+	    _sftbl.sfhdr_p->preamble.version != SFRAME_VERSION_2 ||
+	    !(_sftbl.sfhdr_p->preamble.flags & SFRAME_F_FDE_SORTED)) {
+		pr_warn("WARNING: Unable to read sframe header.  Disabling unwinder.\n");
+		return;
+	}
+
+	_sftbl.fde_p = (struct sframe_fde *)(sframe_buf + SFRAME_HEADER_SIZE(*_sftbl.sfhdr_p)
+						+ _sftbl.sfhdr_p->fdes_off);
+	_sftbl.fre_p = sframe_buf + SFRAME_HEADER_SIZE(*_sftbl.sfhdr_p)
+		+ _sftbl.sfhdr_p->fres_off;
+
+	mod->arch.sftbl = _sftbl;
+	mod->arch.sframe_init = true;
+}
-- 
2.51.0.355.g5224444f11-goog