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

[Dylan Hatch]

From: Weinan Liu <wn...@google.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 <dylanbha...@google.com>
Signed-off-by: Weinan Liu <wn...@google.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