MIPS: Allow the auxv's elf_platform entry to be set.

The userspace runtime linker uses the elf_platform to find the libraries
optimized for the current CPU archecture variant.  First we need to allow it
to be set to something other than NULL.  Follow-on patches will set some
values for specific CPUs.

GLIBC already does the right thing.  The kernel just needs to supply good
data.
Signed-off-by: David Daney <ddaney@caviumnetworks.com>
To: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/891/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/include/asm/elf.h

@@ -334,14 +334,14 @@ extern int dump_task_fpu(struct task_struct *, elf_fpregset_t *);
 
 #define ELF_HWCAP       (0)
 
-/* This yields a string that ld.so will use to load implementation
-   specific libraries for optimization.  This is more specific in
-   intent than poking at uname or /proc/cpuinfo.
-
-   For the moment, we have only optimizations for the Intel generations,
-   but that could change... */
+/*
+ * This yields a string that ld.so will use to load implementation
+ * specific libraries for optimization.  This is more specific in
+ * intent than poking at uname or /proc/cpuinfo.
+ */
 
-#define ELF_PLATFORM  (NULL)
+#define ELF_PLATFORM  __elf_platform
+extern const char *__elf_platform;
 
 /*
  * See comments in asm-alpha/elf.h, this is the same thing

arch/mips/kernel/cpu-probe.c

@@ -926,6 +926,7 @@ static inline void cpu_probe_cavium(struct cpuinfo_mips *c, unsigned int cpu)
 }
 
 const char *__cpu_name[NR_CPUS];
+const char *__elf_platform;
 
 __cpuinit void cpu_probe(void)
 {