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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 /lib/vsprintf.c
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 'lib/vsprintf.c')
-rw-r--r--lib/vsprintf.c5
1 files changed, 2 insertions, 3 deletions
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 1746bae94d41..16e2eefb0f79 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -40,7 +40,6 @@
#include "../mm/internal.h" /* For the trace_print_flags arrays */
#include <asm/page.h> /* for PAGE_SIZE */
-#include <asm/sections.h> /* for dereference_function_descriptor() */
#include <asm/byteorder.h> /* cpu_to_le16 */
#include <linux/string_helpers.h>
@@ -1723,10 +1722,10 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr,
switch (*fmt) {
case 'F':
case 'f':
- ptr = dereference_function_descriptor(ptr);
- /* Fallthrough */
case 'S':
case 's':
+ ptr = dereference_symbol_descriptor(ptr);
+ /* Fallthrough */
case 'B':
return symbol_string(buf, end, ptr, spec, fmt);
case 'R':