[PATCH v6 6/9] arm64/module, sframe: Add sframe support for modules

[Dylan Hatch <dylanbhatch@google.com>]

Add sframe table to mod_arch_specific and support sframe PC lookups when
an .sframe section can be found on incoming modules. SFRAME_F_FDE_SORTED
is not set for module .sframe, so FDES are sorted right after the sframe
header is read.

Signed-off-by: Weinan Liu <wnliu@google.com>
Suggested-by: Jens Remus <jremus@linux.ibm.com>
Reviewed-by: Jens Remus <jremus@linux.ibm.com>
Signed-off-by: Dylan Hatch <dylanbhatch@google.com>
---
 arch/arm64/include/asm/module.h |  6 +++
 arch/arm64/kernel/module.c      |  8 +++
 include/linux/sframe.h          |  3 ++
 kernel/unwind/sframe.c          | 90 +++++++++++++++++++++++++++++++--
 4 files changed, 104 insertions(+), 3 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 5b7341b61a7c..27f5a66190af 100644
--- a/include/linux/sframe.h
+++ b/include/linux/sframe.h
@@ -28,6 +28,7 @@ struct sframe_section {
 	unsigned long		fres_start;
 	unsigned long		fres_end;
 	unsigned int		num_fdes;
+	bool			fdes_sorted;
 
 	signed char		ra_off;
 	signed char		fp_off;
@@ -80,6 +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 c8ec1e9989fc..dfa013450705 100644
--- a/kernel/unwind/sframe.c
+++ b/kernel/unwind/sframe.c
@@ -12,6 +12,7 @@
 #include <linux/mm.h>
 #include <linux/string_helpers.h>
 #include <linux/sframe.h>
+#include <linux/sort.h>
 #include <linux/syscalls.h>
 #include <linux/unwind_types.h>
 #include <asm/unwind_sframe.h>
@@ -186,6 +187,9 @@ static __always_inline int __find_fde(struct sframe_section *sec,
 	struct sframe_fde_v3 *first, *low, *high, *found = NULL;
 	int ret;
 
+	if (!sec->fdes_sorted)
+		return -EINVAL;
+
 	first = (void *)sec->fdes_start;
 	low = first;
 	high = first + sec->num_fdes - 1;
@@ -740,7 +744,6 @@ static int sframe_read_header(struct sframe_section *sec)
 
 	if (shdr.preamble.magic != SFRAME_MAGIC ||
 	    shdr.preamble.version != SFRAME_VERSION_3 ||
-	    !(shdr.preamble.flags & SFRAME_F_FDE_SORTED) ||
 	    !(shdr.preamble.flags & SFRAME_F_FDE_FUNC_START_PCREL) ||
 	    shdr.auxhdr_len) {
 		dbg_sec("bad/unsupported sframe header\n");
@@ -770,6 +773,7 @@ static int sframe_read_header(struct sframe_section *sec)
 		return -EINVAL;
 	}
 
+	sec->fdes_sorted	= shdr.preamble.flags & SFRAME_F_FDE_SORTED;
 	sec->num_fdes		= num_fdes;
 	sec->fdes_start		= fdes_start;
 	sec->fres_start		= fres_start;
@@ -984,10 +988,27 @@ SYSCALL_DEFINE5(stacktrace_setup, int, op, unsigned long, addr_start,
 
 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)
@@ -1004,4 +1025,67 @@ void __init init_sframe_table(void)
 	sframe_init = true;
 }
 
+static int sframe_sort_cmp_fde(const void *a, const void *b)
+{
+	const struct sframe_fde_v3 *fde_a = a, *fde_b = b;
+	unsigned long func_start_a, func_start_b;
+
+	func_start_a = (unsigned long)fde_a + fde_a->func_start_off;
+	func_start_b = (unsigned long)fde_b + fde_b->func_start_off;
+
+	return cmp_int(func_start_a, func_start_b);
+}
+
+static void sframe_sort_swap_fde(void *a, void *b, int size)
+{
+	struct sframe_fde_v3 *fde_a = a, *fde_b = b;
+	struct sframe_fde_v3 temp;
+	long delta;
+
+	/* Swap potentially unaligned FDE */
+	memcpy(&temp, fde_a, sizeof(struct sframe_fde_v3));
+	memcpy(fde_a, fde_b, sizeof(struct sframe_fde_v3));
+	memcpy(fde_b, &temp, sizeof(struct sframe_fde_v3));
+
+	/* Adjust FDE function start offset from FDE */
+	delta = (long)((unsigned long)fde_b - (unsigned long)fde_a);
+	fde_a->func_start_off += delta;
+	fde_b->func_start_off -= delta;
+}
+
+static int sframe_sort_fdes(struct sframe_section *sec)
+{
+	void *fdes = (void *)sec->fdes_start;
+	size_t num_fdes = sec->num_fdes;
+
+	if (sec->sec_type != SFRAME_KERNEL)
+		return -EINVAL;
+	if (sec->fdes_sorted)
+		return 0;
+
+	sort(fdes, num_fdes, sizeof(struct sframe_fde_v3),
+	     sframe_sort_cmp_fde, sframe_sort_swap_fde);
+	sec->fdes_sorted = true;
+	return 0;
+}
+
+void sframe_module_init(struct module *mod, void *sframe, size_t sframe_size,
+			void *text, size_t text_size)
+{
+	struct sframe_section *sec = &mod->arch.sframe_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;
+	if (WARN_ON(sframe_sort_fdes(sec)))
+		return;
+
+	mod->arch.sframe_init = true;
+}
+
 #endif /* CONFIG_HAVE_UNWIND_KERNEL_SFRAME */
-- 
2.54.0.563.g4f69b47b94-goog