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authorSergey Senozhatsky <sergey.senozhatsky.work@gmail.com>2017-12-06 07:36:49 +0300
committerPetr Mladek <pmladek@suse.com>2018-01-09 12:45:38 +0300
commit04b8eb7a4ccd9ef9343e2720ccf2a5db8cfe2f67 (patch)
treec9f3302f30c62d5ba093f3abeffe168be0de9eee /include/linux/kallsyms.h
parent1705bd6a68171d8b3ba05df9352757ee4e49317b (diff)
downloadlinux-04b8eb7a4ccd9ef9343e2720ccf2a5db8cfe2f67.tar.xz
symbol lookup: introduce dereference_symbol_descriptor()
dereference_symbol_descriptor() invokes appropriate ARCH specific function descriptor dereference callbacks: - dereference_kernel_function_descriptor() if the pointer is a kernel symbol; - dereference_module_function_descriptor() if the pointer is a module symbol. This is the last step needed to make '%pS/%ps' smart enough to handle function descriptor dereference on affected ARCHs and to retire '%pF/%pf'. To refresh it: Some architectures (ia64, ppc64, parisc64) use an indirect pointer for C function pointers - the function pointer points to a function descriptor and we need to dereference it to get the actual function pointer. Function descriptors live in .opd elf section and all affected ARCHs (ia64, ppc64, parisc64) handle it properly for kernel and modules. So we, technically, can decide if the dereference is needed by simply looking at the pointer: if it belongs to .opd section then we need to dereference it. The kernel and modules have their own .opd sections, obviously, that's why we need to split dereference_function_descriptor() and use separate kernel and module dereference arch callbacks. Link: http://lkml.kernel.org/r/20171206043649.GB15885@jagdpanzerIV Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: James Bottomley <jejb@parisc-linux.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Jessica Yu <jeyu@kernel.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: linux-ia64@vger.kernel.org Cc: linux-parisc@vger.kernel.org Cc: linuxppc-dev@lists.ozlabs.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Tested-by: Tony Luck <tony.luck@intel.com> #ia64 Tested-by: Santosh Sivaraj <santosh@fossix.org> #powerpc Tested-by: Helge Deller <deller@gmx.de> #parisc64 Signed-off-by: Petr Mladek <pmladek@suse.com>
Diffstat (limited to 'include/linux/kallsyms.h')
-rw-r--r--include/linux/kallsyms.h54
1 files changed, 54 insertions, 0 deletions
diff --git a/include/linux/kallsyms.h b/include/linux/kallsyms.h
index 708f337d780b..e4f2e5a65f14 100644
--- a/include/linux/kallsyms.h
+++ b/include/linux/kallsyms.h
@@ -9,6 +9,10 @@
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/stddef.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+
+#include <asm/sections.h>
#define KSYM_NAME_LEN 128
#define KSYM_SYMBOL_LEN (sizeof("%s+%#lx/%#lx [%s]") + (KSYM_NAME_LEN - 1) + \
@@ -22,6 +26,56 @@
struct module;
+static inline int is_kernel_inittext(unsigned long addr)
+{
+ if (addr >= (unsigned long)_sinittext
+ && addr <= (unsigned long)_einittext)
+ return 1;
+ return 0;
+}
+
+static inline int is_kernel_text(unsigned long addr)
+{
+ if ((addr >= (unsigned long)_stext && addr <= (unsigned long)_etext) ||
+ arch_is_kernel_text(addr))
+ return 1;
+ return in_gate_area_no_mm(addr);
+}
+
+static inline int is_kernel(unsigned long addr)
+{
+ if (addr >= (unsigned long)_stext && addr <= (unsigned long)_end)
+ return 1;
+ return in_gate_area_no_mm(addr);
+}
+
+static inline int is_ksym_addr(unsigned long addr)
+{
+ if (IS_ENABLED(CONFIG_KALLSYMS_ALL))
+ return is_kernel(addr);
+
+ return is_kernel_text(addr) || is_kernel_inittext(addr);
+}
+
+static inline void *dereference_symbol_descriptor(void *ptr)
+{
+#ifdef HAVE_DEREFERENCE_FUNCTION_DESCRIPTOR
+ struct module *mod;
+
+ ptr = dereference_kernel_function_descriptor(ptr);
+ if (is_ksym_addr((unsigned long)ptr))
+ return ptr;
+
+ preempt_disable();
+ mod = __module_address((unsigned long)ptr);
+ preempt_enable();
+
+ if (mod)
+ ptr = dereference_module_function_descriptor(mod, ptr);
+#endif
+ return ptr;
+}
+
#ifdef CONFIG_KALLSYMS
/* Lookup the address for a symbol. Returns 0 if not found. */
unsigned long kallsyms_lookup_name(const char *name);