ARM: 6511/1: ftrace: add ARM support for C version of recordmcount

Depending on the compiler version, ARM GCC calls the mcount function
either __gnu_mcount_nc or mcount.

Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Rabin Vincent <rabin@rab.in>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

3 files changed, 8 insertions, 3 deletions

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index db524e75c4a2..a7b9070b661e 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -23,6 +23,7 @@ config ARM
         select PERF_USE_VMALLOC
         select HAVE_REGS_AND_STACK_ACCESS_API
         select HAVE_HW_BREAKPOINT if (PERF_EVENTS && (CPU_V6 || CPU_V7))
+        select HAVE_C_RECORDMCOUNT
         help
           The ARM series is a line of low-power-consumption RISC chip designs
           licensed by ARM Ltd and targeted at embedded applications and
diff --git a/scripts/recordmcount.c b/scripts/recordmcount.c
index ac6e51ceed50..038b3d1e2981 100644
--- a/scripts/recordmcount.c
+++ b/scripts/recordmcount.c
@@ -38,6 +38,7 @@ static void *ehdr_curr; /* current ElfXX_Ehdr *  for resource cleanup */
 static char gpfx;       /* prefix for global symbol name (sometimes '_') */
 static struct stat sb;  /* Remember .st_size, etc. */
 static jmp_buf jmpenv;  /* setjmp/longjmp per-file error escape */
+static const char *altmcount;   /* alternate mcount symbol name */
 
 /* setjmp() return values */
 enum {
@@ -299,7 +300,9 @@ do_file(char const *const fname)
                 fail_file();
         } break;
         case EM_386:     reltype = R_386_32;                   break;
-        case EM_ARM:     reltype = R_ARM_ABS32;                break;
+        case EM_ARM:     reltype = R_ARM_ABS32;
+                         altmcount = "__gnu_mcount_nc";
+                         break;
         case EM_IA_64:   reltype = R_IA64_IMM64;   gpfx = '_'; break;
         case EM_MIPS:    /* reltype: e_class    */ gpfx = '_'; break;
         case EM_PPC:     reltype = R_PPC_ADDR32;   gpfx = '_'; break;
diff --git a/scripts/recordmcount.h b/scripts/recordmcount.h
index 58e933a20544..8087bc8cd2d1 100644
--- a/scripts/recordmcount.h
+++ b/scripts/recordmcount.h
@@ -275,11 +275,12 @@ static uint_t *sift_rel_mcount(uint_t *mlocp,
                         Elf_Sym const *const symp =
                                 &sym0[Elf_r_sym(relp)];
                         char const *symname = &str0[w(symp->st_name)];
+                        char const *mcount = '_' == gpfx ? "_mcount" : "mcount";
 
                         if ('.' == symname[0])
                                 ++symname;  /* ppc64 hack */
-                        if (0 == strcmp((('_' == gpfx) ? "_mcount" : "mcount"),
-                                        symname))
+                        if (0 == strcmp(mcount, symname) ||
+                            (altmcount && 0 == strcmp(altmcount, symname)))
                                 mcountsym = Elf_r_sym(relp);
                 }