From: Weinan Liu <wn...@google.com>
This change introduces a kernel space unwinder using sframe table for
architectures without ORC unwinder support.
The implementation is adapted from Josh's userspace sframe unwinder
proposal[1] according to the sframe v2 spec[2].
[1]
https://lore.kernel.org/lkml/42c0a99236af65c09c8182e260af7bcf5aa1e158.1730150953.git.jpoim...@kernel.org/
[2] https://sourceware.org/binutils/docs/sframe-spec.html
Signed-off-by: Weinan Liu <wn...@google.com>
Signed-off-by: Dylan Hatch <dylanbha...@google.com>
Reviewed-by: Prasanna Kumar T S M <p...@linux.microsoft.com>
---
include/linux/sframe_lookup.h | 43 ++++++++
kernel/Makefile | 1 +
kernel/sframe_lookup.c | 196 ++++++++++++++++++++++++++++++++++
3 files changed, 240 insertions(+)
create mode 100644 include/linux/sframe_lookup.h
create mode 100644 kernel/sframe_lookup.c
diff --git a/include/linux/sframe_lookup.h b/include/linux/sframe_lookup.h
new file mode 100644
index 000000000000..1c26cf1f38d4
--- /dev/null
+++ b/include/linux/sframe_lookup.h
@@ -0,0 +1,43 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_SFRAME_LOOKUP_H
+#define _LINUX_SFRAME_LOOKUP_H
+
+/**
+ * struct sframe_ip_entry - sframe unwind info for given ip
+ * @cfa_offset: Offset for the Canonical Frame Address(CFA) from Frame
+ * Pointer(FP) or Stack Pointer(SP)
+ * @ra_offset: Offset for the Return Address from CFA.
+ * @fp_offset: Offset for the Frame Pointer (FP) from CFA.
+ * @use_fp: Use FP to get next CFA or not
+ */
+struct sframe_ip_entry {
+ int32_t cfa_offset;
+ int32_t ra_offset;
+ int32_t fp_offset;
+ bool use_fp;
+};
+
+/**
+ * struct sframe_table - sframe struct of a table
+ * @sfhdr_p: Pointer to sframe header
+ * @fde_p: Pointer to the first of sframe frame description entry(FDE).
+ * @fre_p: Pointer to the first of sframe frame row entry(FRE).
+ */
+struct sframe_table {
+ struct sframe_header *sfhdr_p;
+ struct sframe_fde *fde_p;
+ char *fre_p;
+};
+
+#ifdef CONFIG_SFRAME_UNWINDER
+void init_sframe_table(void);
+int sframe_find_pc(unsigned long pc, struct sframe_ip_entry *entry);
+#else
+static inline void init_sframe_table(void) {}
+static inline int sframe_find_pc(unsigned long pc, struct sframe_ip_entry
*entry)
+{
+ return -EINVAL;
+}
+#endif
+
+#endif /* _LINUX_SFRAME_LOOKUP_H */
diff --git a/kernel/Makefile b/kernel/Makefile
index c60623448235..17e9cfe09dc0 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -138,6 +138,7 @@ obj-$(CONFIG_WATCH_QUEUE) += watch_queue.o
obj-$(CONFIG_RESOURCE_KUNIT_TEST) += resource_kunit.o
obj-$(CONFIG_SYSCTL_KUNIT_TEST) += sysctl-test.o
+obj-$(CONFIG_SFRAME_UNWINDER) += sframe_lookup.o
CFLAGS_kstack_erase.o += $(DISABLE_KSTACK_ERASE)
CFLAGS_kstack_erase.o += $(call cc-option,-mgeneral-regs-only)
diff --git a/kernel/sframe_lookup.c b/kernel/sframe_lookup.c
new file mode 100644
index 000000000000..51cd24a75956
--- /dev/null
+++ b/kernel/sframe_lookup.c
@@ -0,0 +1,196 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#define pr_fmt(fmt) "sframe: " fmt
+
+#include <linux/module.h>
+#include <linux/sort.h>
+#include <linux/sframe_lookup.h>
+#include <linux/kallsyms.h>
+#include "sframe.h"
+
+extern char __start_sframe_header[];
+extern char __stop_sframe_header[];
+
+static bool sframe_init __ro_after_init;
+static struct sframe_table sftbl;
+
+#define SFRAME_READ_TYPE(in, out, type)
\
+({ \
+ type __tmp; \
+ memcpy(&__tmp, in, sizeof(__tmp)); \
+ in += sizeof(__tmp); \
+ out = __tmp; \
+})
+
+#define SFRAME_READ_ROW_ADDR(in_addr, out_addr, type) \
+({ \
+ switch (type) { \
+ case SFRAME_FRE_TYPE_ADDR1: \
+ SFRAME_READ_TYPE(in_addr, out_addr, u8); \
+ break; \
+ case SFRAME_FRE_TYPE_ADDR2: \
+ SFRAME_READ_TYPE(in_addr, out_addr, u16); \
+ break; \
+ case SFRAME_FRE_TYPE_ADDR4: \
+ SFRAME_READ_TYPE(in_addr, out_addr, u32); \
+ break; \
+ default: \
+ break; \
+ } \
+})
+
+#define SFRAME_READ_ROW_OFFSETS(in_addr, out_addr, size) \
+({ \
+ switch (size) { \
+ case 1: \
+ SFRAME_READ_TYPE(in_addr, out_addr, s8); \
+ break; \
+ case 2: \
+ SFRAME_READ_TYPE(in_addr, out_addr, s16); \
+ break; \
+ case 4: \
+ SFRAME_READ_TYPE(in_addr, out_addr, s32); \
+ break; \
+ default: \
+ break; \
+ } \
+})
+
+static struct sframe_fde *find_fde(const struct sframe_table *tbl, unsigned
long pc)
+{
+ int l, r, m, f;
+ int32_t ip;
+ struct sframe_fde *fdep;
+
+ if (!tbl || !tbl->sfhdr_p || !tbl->fde_p)
+ return NULL;
+
+ ip = (pc - (unsigned long)tbl->sfhdr_p);
+
+ /* Do a binary range search to find the rightmost FDE start_addr < ip */
+ l = m = f = 0;
+ r = tbl->sfhdr_p->num_fdes;
+ while (l < r) {
+ m = l + ((r - l) / 2);
+ fdep = tbl->fde_p + m;
+ if (fdep->start_addr > ip)
+ r = m;
+ else
+ l = m + 1;
+ }
