[PATCH 1/2] kallsyms: architecture specific symbol lookups

[Nicholas Piggin]

Provide CONFIG_ARCH_HAS_ADDRESS_LOOKUP which allows architectures to
do their own symbol/address lookup if kernel and module lookups miss.

powerpc will use this to deal with firmware symbols.

Signed-off-by: Nicholas Piggin <npig...@gmail.com>
---
 include/linux/kallsyms.h | 20 ++++++++++++++++++++
 kernel/kallsyms.c        | 13 ++++++++++++-
 lib/Kconfig              |  3 +++
 3 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/include/linux/kallsyms.h b/include/linux/kallsyms.h
index 657a83b943f0..8fdd44873373 100644
--- a/include/linux/kallsyms.h
+++ b/include/linux/kallsyms.h
@@ -83,6 +83,26 @@ extern int kallsyms_lookup_size_offset(unsigned long addr,
                                  unsigned long *symbolsize,
                                  unsigned long *offset);
 
+#ifdef CONFIG_ARCH_HAS_ADDRESS_LOOKUP
+const char *arch_address_lookup(unsigned long addr,
+                           unsigned long *symbolsize,
+                           unsigned long *offset,
+                           char **modname, char *namebuf);
+unsigned long arch_address_lookup_name(const char *name);
+#else
+static inline const char *arch_address_lookup(unsigned long addr,
+                           unsigned long *symbolsize,
+                           unsigned long *offset,
+                           char **modname, char *namebuf)
+{
+       return NULL;
+}
+static inline unsigned long arch_address_lookup_name(const char *name)
+{
+       return 0;
+}
+#endif
+
 /* Lookup an address.  modname is set to NULL if it's in the kernel. */
 const char *kallsyms_lookup(unsigned long addr,
                            unsigned long *symbolsize,
diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c
index a9b3f660dee7..580c762fadd8 100644
--- a/kernel/kallsyms.c
+++ b/kernel/kallsyms.c
@@ -164,6 +164,7 @@ static unsigned long kallsyms_sym_address(int idx)
 unsigned long kallsyms_lookup_name(const char *name)
 {
        char namebuf[KSYM_NAME_LEN];
+       unsigned long ret;
        unsigned long i;
        unsigned int off;
 
@@ -173,7 +174,12 @@ unsigned long kallsyms_lookup_name(const char *name)
                if (strcmp(namebuf, name) == 0)
                        return kallsyms_sym_address(i);
        }
-       return module_kallsyms_lookup_name(name);
+
+       ret = module_kallsyms_lookup_name(name);
+       if (ret)
+               return ret;
+
+       return arch_address_lookup_name(name);
 }
 EXPORT_SYMBOL_GPL(kallsyms_lookup_name);
 
@@ -311,6 +317,11 @@ const char *kallsyms_lookup(unsigned long addr,
        if (!ret)
                ret = ftrace_mod_address_lookup(addr, symbolsize,
                                                offset, modname, namebuf);
+
+       if (!ret)
+               ret = arch_address_lookup(addr, symbolsize,
+                                               offset, modname, namebuf);
+
        return ret;
 }
 
diff --git a/lib/Kconfig b/lib/Kconfig
index bc7e56370129..16d3b8dbcadf 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -80,6 +80,9 @@ config ARCH_USE_CMPXCHG_LOCKREF
 config ARCH_HAS_FAST_MULTIPLIER
        bool
 
+config ARCH_HAS_ADDRESS_LOOKUP
+       bool
+
 config INDIRECT_PIO
        bool "Access I/O in non-MMIO mode"
        depends on ARM64
-- 
2.23.0