[PATCH v7 01/11] arm64, unwind: build kernel with sframe V3 info
From: Dylan Hatch
Date: Fri Sep 18 2026 - 18:42:50 EST
To generate a .sframe section, build with -Wa,--gsframe-3 flags. Also,
add unwind-table options to ensure the necessary CFI directives are
emitted by the compiler, but discard .eh_frame unless
CONFIG_UNWIND_TABLES is explicitly enabled.
This will be used for in-kernel reliable stacktrace in
cases where the frame pointer alone is insufficient.
Currently, the sframe format only supports arm64, x86_64 and s390x
architectures.
Co-developed-by: Weinan Liu <wnliu@xxxxxxxxxx>
Signed-off-by: Weinan Liu <wnliu@xxxxxxxxxx>
Reviewed-by: Prasanna Kumar T S M <ptsm@xxxxxxxxxxxxxxxxxxx>
Reviewed-by: Jens Remus <jremus@xxxxxxxxxxxxx>
Signed-off-by: Dylan Hatch <dylanbhatch@xxxxxxxxxx>
---
Changes since v6:
- Moved to beginning of series
- Squashed in AS_SFRAME, AS_SFRAME3, and UNWIND_SFRAME_LOOKUP config
definitions.
- Squashed in STACK UNWINDING change in MAINTAINERS file.
- Dropped SFRAME_REG_SP / SFRAME_REG_FP definitions.
- Added -fasynchronous-unwind-tables so CFI directives are emitted by
compiler.
- Discard .eh_frame sections when CONFIG_UNWIND_TABLES is not set.
---
MAINTAINERS | 3 ++-
Makefile | 8 ++++++++
arch/Kconfig | 31 +++++++++++++++++++++++++++++
arch/arm64/Kconfig | 1 +
arch/arm64/Makefile | 2 +-
arch/arm64/include/asm/module.lds.h | 2 ++
arch/arm64/kernel/vdso/Makefile | 2 +-
arch/arm64/kernel/vmlinux.lds.S | 12 +++++++++++
include/asm-generic/sections.h | 4 ++++
include/asm-generic/vmlinux.lds.h | 15 ++++++++++++++
10 files changed, 77 insertions(+), 3 deletions(-)
diff --git a/MAINTAINERS b/MAINTAINERS
index c2414447892c2..6c1c95979e437 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -28514,10 +28514,11 @@ F: Documentation/driver-api/uio-howto.rst
F: drivers/uio/
F: include/linux/uio_driver.h
-USERSPACE STACK UNWINDING
+STACK UNWINDING
M: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
M: Steven Rostedt <rostedt@xxxxxxxxxxx>
S: Maintained
+F: arch/*/include/asm/unwind_sframe.h
F: include/linux/unwind*.h
F: kernel/unwind/
diff --git a/Makefile b/Makefile
index 0f1b80100b479..5ed4a59e71aac 100644
--- a/Makefile
+++ b/Makefile
@@ -1197,6 +1197,14 @@ CFLAGS_GCOV += $(call try-run,\
endif
export CFLAGS_GCOV
+# build with sframe table
+ifdef CONFIG_HAVE_UNWIND_KERNEL_SFRAME
+CC_FLAGS_SFRAME := -Wa,--gsframe-3
+KBUILD_CFLAGS += $(CC_FLAGS_SFRAME)
+KBUILD_AFLAGS += $(CC_FLAGS_SFRAME)
+export CC_FLAGS_SFRAME
+endif
+
# change __FILE__ to the relative path to the source directory
ifdef building_out_of_srctree
KBUILD_CPPFLAGS += -fmacro-prefix-map=$(srcroot)/=
diff --git a/arch/Kconfig b/arch/Kconfig
index 45c6577723623..cc59a5da80915 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -507,6 +507,37 @@ config HAVE_UNWIND_USER_FP
bool
select UNWIND_USER
+config AS_SFRAME
+ bool
+
+config AS_SFRAME3
+ def_bool $(as-instr,.cfi_startproc\n.cfi_endproc,-Wa$(comma)--gsframe-3)
+ select AS_SFRAME
+
+config UNWIND_SFRAME_LOOKUP
+ bool
+
+config ARCH_SUPPORTS_UNWIND_KERNEL_SFRAME
+ bool
+ help
+ An architecture can select this if it enables the SFrame (Simple
+ Frame) unwinder for unwinding kernel stack traces. It uses an unwind
+ table that is directly generated by the toolchain based on DWARF CFI
+ information.
+
+config HAVE_UNWIND_KERNEL_SFRAME
+ bool "Sframe unwinder"
+ depends on AS_SFRAME3
+ depends on 64BIT
+ depends on ARCH_SUPPORTS_UNWIND_KERNEL_SFRAME
+ select UNWIND_SFRAME_LOOKUP
+ help
+ This option enables the SFrame (Simple Frame) unwinder for unwinding
+ kernel stack traces. It uses an unwind table that is directly
+ generated by the toolchain based on DWARF CFI information. In
+ practice, this can provide more reliable stacktrace results than
+ unwinding with frame pointers alone.
+
config HAVE_PERF_REGS
bool
help
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index b5a51b0ef9440..041de63a659d1 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -87,6 +87,7 @@ config ARM64
select ARCH_SUPPORTS_SCHED_SMT
select ARCH_SUPPORTS_SCHED_CLUSTER
select ARCH_SUPPORTS_SCHED_MC
+ select ARCH_SUPPORTS_UNWIND_KERNEL_SFRAME
select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
select ARCH_WANT_COMPAT_IPC_PARSE_VERSION if COMPAT
select ARCH_WANT_DEFAULT_BPF_JIT
diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile
index 6b005c8fef706..ae1c23579ad2f 100644
--- a/arch/arm64/Makefile
+++ b/arch/arm64/Makefile
@@ -55,7 +55,7 @@ KBUILD_CFLAGS += $(call cc-option,-mabi=lp64)
KBUILD_AFLAGS += $(call cc-option,-mabi=lp64)
# Avoid generating .eh_frame* sections.
-ifneq ($(CONFIG_UNWIND_TABLES),y)
+ifeq ($(filter y, $(CONFIG_UNWIND_TABLES) $(CONFIG_HAVE_UNWIND_KERNEL_SFRAME)),)
KBUILD_CFLAGS += -fno-asynchronous-unwind-tables -fno-unwind-tables
KBUILD_AFLAGS += -fno-asynchronous-unwind-tables -fno-unwind-tables
KBUILD_RUSTFLAGS += -Cforce-unwind-tables=n
diff --git a/arch/arm64/include/asm/module.lds.h b/arch/arm64/include/asm/module.lds.h
index 603f92a8a73ed..034cb635e8bcc 100644
--- a/arch/arm64/include/asm/module.lds.h
+++ b/arch/arm64/include/asm/module.lds.h
@@ -10,5 +10,7 @@ SECTIONS {
* put it into the .init allocation.
*/
.init.eh_frame 0 : { *(.eh_frame) }
+#elif defined(CONFIG_HAVE_UNWIND_KERNEL_SFRAME)
+ /DISCARD/ : { *(.eh_frame) }
#endif
}
diff --git a/arch/arm64/kernel/vdso/Makefile b/arch/arm64/kernel/vdso/Makefile
index 7dec05dd33b70..c60ef921956fb 100644
--- a/arch/arm64/kernel/vdso/Makefile
+++ b/arch/arm64/kernel/vdso/Makefile
@@ -38,7 +38,7 @@ ccflags-y += -DDISABLE_BRANCH_PROFILING -DBUILD_VDSO
CC_FLAGS_REMOVE_VDSO := $(CC_FLAGS_FTRACE) -Os $(CC_FLAGS_SCS) \
$(RANDSTRUCT_CFLAGS) $(KSTACK_ERASE_CFLAGS) \
$(GCC_PLUGINS_CFLAGS) \
- $(CC_FLAGS_LTO) $(CC_FLAGS_CFI) \
+ $(CC_FLAGS_LTO) $(CC_FLAGS_CFI) $(CC_FLAGS_SFRAME) \
-Wmissing-prototypes -Wmissing-declarations
CC_FLAGS_ADD_VDSO := -O2 -mcmodel=tiny -fasynchronous-unwind-tables
diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S
index af1d720209764..eb1f54829503c 100644
--- a/arch/arm64/kernel/vmlinux.lds.S
+++ b/arch/arm64/kernel/vmlinux.lds.S
@@ -145,14 +145,25 @@ jiffies = jiffies_64;
#endif
#ifdef CONFIG_UNWIND_TABLES
+
#define UNWIND_DATA_SECTIONS \
.eh_frame : { \
__pi___eh_frame_start = .; \
*(.eh_frame) \
__pi___eh_frame_end = .; \
}
+#define SFRAME_DISCARDS
+
+#elif defined(CONFIG_HAVE_UNWIND_KERNEL_SFRAME)
+
+#define UNWIND_DATA_SECTIONS
+#define SFRAME_DISCARDS *(.eh_frame)
+
#else
+
#define UNWIND_DATA_SECTIONS
+#define SFRAME_DISCARDS
+
#endif
/*
@@ -184,6 +195,7 @@ SECTIONS
*(.interp .dynamic)
*(.dynsym .dynstr .hash .gnu.hash)
*(.ARM.attributes)
+ SFRAME_DISCARDS
}
. = KIMAGE_VADDR;
diff --git a/include/asm-generic/sections.h b/include/asm-generic/sections.h
index 0755bc39b0d80..336d27011a580 100644
--- a/include/asm-generic/sections.h
+++ b/include/asm-generic/sections.h
@@ -31,6 +31,7 @@
* __irqentry_text_start, __irqentry_text_end
* __softirqentry_text_start, __softirqentry_text_end
* __start_opd, __end_opd
+ * __start_sframe, __end_sframe
*/
extern char _text[], _stext[], _etext[];
extern char _data[], _sdata[], _edata[];
@@ -53,6 +54,9 @@ extern char __ctors_start[], __ctors_end[];
/* Start and end of .opd section - used for function descriptors. */
extern char __start_opd[], __end_opd[];
+/* Start and end of .sframe section - used for stack unwinding. */
+extern char __start_sframe[], __end_sframe[];
+
/* Start and end of instrumentation protected text section */
extern char __noinstr_text_start[], __noinstr_text_end[];
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index b2988aa12f664..278f5764d990d 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -491,6 +491,8 @@
*(.rodata1) \
} \
\
+ SFRAME \
+ \
/* PCI quirks */ \
.pci_fixup : AT(ADDR(.pci_fixup) - LOAD_OFFSET) { \
BOUNDED_SECTION_PRE_LABEL(.pci_fixup_early, _pci_fixups_early, __start, __end) \
@@ -912,6 +914,19 @@
#define TRACEDATA
#endif
+#ifdef CONFIG_HAVE_UNWIND_KERNEL_SFRAME
+#define SFRAME \
+ /* sframe */ \
+ .sframe : AT(ADDR(.sframe) - LOAD_OFFSET) { \
+ __start_sframe = .; \
+ KEEP(*(.sframe)) \
+ KEEP(*(.init.sframe)) \
+ __end_sframe = .; \
+ }
+#else
+#define SFRAME
+#endif
+
#ifdef CONFIG_PRINTK_INDEX
#define PRINTK_INDEX \
.printk_index : AT(ADDR(.printk_index) - LOAD_OFFSET) { \
--
2.55.0.1082.g2b9226bbc0-goog