[PATCH v4 6/8] arm64/module, sframe: Add sframe support for modules

[Dylan Hatch]

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

Signed-off-by: Weinan Liu <wnliu at google.com>
Reviewed-by: Jens Remus <jremus at linux.ibm.com>
Signed-off-by: Dylan Hatch <dylanbhatch at google.com>
---
 arch/arm64/include/asm/module.h |  6 +++++
 arch/arm64/kernel/module.c      |  8 +++++++
 include/linux/sframe.h          |  2 ++
 kernel/unwind/sframe.c          | 40 +++++++++++++++++++++++++++++++--
 4 files changed, 54 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/include/asm/module.h b/arch/arm64/include/asm/module.h
index fb9b88eebeb1..07f309c51eee 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.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_HAVE_UNWIND_KERNEL_SFRAME
+	struct sframe_section sframe_sec;
+	bool sframe_init;
+#endif
+
 	/* for CONFIG_DYNAMIC_FTRACE */
 	struct plt_entry	*ftrace_trampolines;
 	struct plt_entry	*init_ftrace_trampolines;
diff --git a/arch/arm64/kernel/module.c b/arch/arm64/kernel/module.c
index 24adb581af0e..427f187e9531 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.h>
 
 #include <asm/alternative.h>
 #include <asm/insn.h>
@@ -515,5 +516,12 @@ int module_finalize(const Elf_Ehdr *hdr,
 		}
 	}
 
+	s = find_section(hdr, sechdrs, ".sframe");
+	if (s) {
+		struct module_memory *t = &me->mem[MOD_TEXT];
+
+		sframe_module_init(me, (void *)s->sh_addr, s->sh_size,
+				   t->base, t->size);
+	}
 	return module_init_ftrace_plt(hdr, sechdrs, me);
 }
diff --git a/include/linux/sframe.h b/include/linux/sframe.h
index 8ae31ed36226..27f5a66190af 100644
--- a/include/linux/sframe.h
+++ b/include/linux/sframe.h
@@ -81,6 +81,8 @@ extern int sframe_find_kernel(unsigned long ip, struct unwind_frame *frame);
 #else
 
 static inline void __init init_sframe_table(void) {}
+static inline void sframe_module_init(struct module *mod, void *sframe, size_t sframe_size,
+				      void *text, size_t text_size) {}
 
 #endif /* CONFIG_HAVE_UNWIND_KERNEL_SFRAME */
 
diff --git a/kernel/unwind/sframe.c b/kernel/unwind/sframe.c
index 243027244854..20178e02f428 100644
--- a/kernel/unwind/sframe.c
+++ b/kernel/unwind/sframe.c
@@ -980,10 +980,27 @@ void sframe_free_mm(struct mm_struct *mm)
 
 int sframe_find_kernel(unsigned long ip, struct unwind_frame *frame)
 {
-	if (!frame || !sframe_init)
+	struct sframe_section *sec;
+
+	if (!frame)
 		return -EINVAL;
 
-	return  __sframe_find(&kernel_sfsec, ip, frame);
+	if (is_ksym_addr(ip)) {
+		if (!sframe_init)
+			return -EINVAL;
+
+		sec = &kernel_sfsec;
+	} else {
+		struct module *mod;
+
+		mod = __module_address(ip);
+		if (!mod || !mod->arch.sframe_init)
+			return -EINVAL;
+
+		sec = &mod->arch.sframe_sec;
+	}
+
+	return  __sframe_find(sec, ip, frame);
 }
 
 void __init init_sframe_table(void)
@@ -1000,4 +1017,23 @@ void __init init_sframe_table(void)
 	sframe_init = true;
 }
 
+void sframe_module_init(struct module *mod, void *sframe, size_t sframe_size,
+			void *text, size_t text_size)
+{
+	struct sframe_section sec;
+
+	memset(&sec, 0, sizeof(sec));
+	sec.sec_type	 = SFRAME_KERNEL;
+	sec.sframe_start = (unsigned long)sframe;
+	sec.sframe_end   = (unsigned long)sframe + sframe_size;
+	sec.text_start   = (unsigned long)text;
+	sec.text_end     = (unsigned long)text + text_size;
+
+	if (WARN_ON(sframe_read_header(&sec)))
+		return;
+
+	mod->arch.sframe_sec = sec;
+	mod->arch.sframe_init = true;
+}
+
 #endif /* CONFIG_HAVE_UNWIND_KERNEL_SFRAME */
-- 
2.54.0.rc1.555.g9c883467ad-goog