ARM: 8788/1: ftrace: remove old mcount support

Commit cafa0010cd51 ("Raise the minimum required gcc version to 4.6")
raised the minimum GCC version to 4.6. Old mcount is only required for
GCC versions older than 4.4.0. Hence old mcount support can be dropped
too.

Signed-off-by: Stefan Agner <stefan@agner.ch>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
[sw0312.kim: cherry-pick maline commit d3c61619568c to support llvm/clang build
 - FRAME_POINTER is required for old gcc version, and it is not really necessary for llvm/clang ]
Signed-off-by: Seung-Woo Kim <sw0312.kim@samsung.com>
Change-Id: I42e61d4e9f146eeaa728b3febbf0f9782b879ee0

diff --git a/arch/arm/Kconfig.debug b/arch/arm/Kconfig.debug
index f6fcb8a..c155b11 100644 (file)
--- a/arch/arm/Kconfig.debug
+++ b/arch/arm/Kconfig.debug
@@ -70,11 +70,6 @@ config ARM_UNWIND
          the performance is not affected. Currently, this feature
          only works with EABI compilers. If unsure say Y.
 
-config OLD_MCOUNT
-       bool
-       depends on FUNCTION_TRACER && FRAME_POINTER
-       default y
-
 config DEBUG_USER
        bool "Verbose user fault messages"
        help

diff --git a/arch/arm/include/asm/ftrace.h b/arch/arm/include/asm/ftrace.h
index 9e842ff..18b0197 100644 (file)
--- a/arch/arm/include/asm/ftrace.h
+++ b/arch/arm/include/asm/ftrace.h
@@ -16,9 +16,6 @@ extern void __gnu_mcount_nc(void);
 
 #ifdef CONFIG_DYNAMIC_FTRACE
 struct dyn_arch_ftrace {
-#ifdef CONFIG_OLD_MCOUNT
-       bool    old_mcount;
-#endif
 };
 
 static inline unsigned long ftrace_call_adjust(unsigned long addr)

diff --git a/arch/arm/kernel/armksyms.c b/arch/arm/kernel/armksyms.c
index 783fbb4..8fa2dc2 100644 (file)
--- a/arch/arm/kernel/armksyms.c
+++ b/arch/arm/kernel/armksyms.c
@@ -167,9 +167,6 @@ EXPORT_SYMBOL(_find_next_bit_be);
 #endif
 
 #ifdef CONFIG_FUNCTION_TRACER
-#ifdef CONFIG_OLD_MCOUNT
-EXPORT_SYMBOL(mcount);
-#endif
 EXPORT_SYMBOL(__gnu_mcount_nc);
 #endif
 

diff --git a/arch/arm/kernel/entry-ftrace.S b/arch/arm/kernel/entry-ftrace.S
index efcd9f2..0be69e5 100644 (file)
--- a/arch/arm/kernel/entry-ftrace.S
+++ b/arch/arm/kernel/entry-ftrace.S
@@ -15,23 +15,8 @@
  * start of every function.  In mcount, apart from the function's address (in
  * lr), we need to get hold of the function's caller's address.
  *
- * Older GCCs (pre-4.4) inserted a call to a routine called mcount like this:
- *
- *     bl      mcount
- *
- * These versions have the limitation that in order for the mcount routine to
- * be able to determine the function's caller's address, an APCS-style frame
- * pointer (which is set up with something like the code below) is required.
- *
- *     mov     ip, sp
- *     push    {fp, ip, lr, pc}
- *     sub     fp, ip, #4
- *
- * With EABI, these frame pointers are not available unless -mapcs-frame is
- * specified, and if building as Thumb-2, not even then.
- *
- * Newer GCCs (4.4+) solve this problem by introducing a new version of mcount,
- * with call sites like:
+ * Newer GCCs (4.4+) solve this problem by using a version of mcount with call
+ * sites like:
  *
  *     push    {lr}
  *     bl      __gnu_mcount_nc
@@ -46,17 +31,10 @@
  * allows it to be clobbered in subroutines and doesn't use it to hold
  * parameters.)
  *
- * When using dynamic ftrace, we patch out the mcount call by a "mov r0, r0"
- * for the mcount case, and a "pop {lr}" for the __gnu_mcount_nc case (see
- * arch/arm/kernel/ftrace.c).
+ * When using dynamic ftrace, we patch out the mcount call by a "pop {lr}"
+ * instead of the __gnu_mcount_nc call (see arch/arm/kernel/ftrace.c).
  */
 
-#ifndef CONFIG_OLD_MCOUNT
-#if (__GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 4))
-#error Ftrace requires CONFIG_FRAME_POINTER=y with GCC older than 4.4.0.
-#endif
-#endif
-
 .macro mcount_adjust_addr rd, rn
        bic     \rd, \rn, #1            @ clear the Thumb bit if present
        sub     \rd, \rd, #MCOUNT_INSN_SIZE
@@ -209,51 +187,6 @@ ftrace_graph_call\suffix:
        mcount_exit
 .endm
 
-#ifdef CONFIG_OLD_MCOUNT
-/*
- * mcount
- */
-
-.macro mcount_enter
-       stmdb   sp!, {r0-r3, lr}
-.endm
-
-.macro mcount_get_lr reg
-       ldr     \reg, [fp, #-4]
-.endm
-
-.macro mcount_exit
-       ldr     lr, [fp, #-4]
-       ldmia   sp!, {r0-r3, pc}
-.endm
-
-ENTRY(mcount)
-#ifdef CONFIG_DYNAMIC_FTRACE
-       stmdb   sp!, {lr}
-       ldr     lr, [fp, #-4]
-       ldmia   sp!, {pc}
-#else
-       __mcount _old
-#endif
-ENDPROC(mcount)
-
-#ifdef CONFIG_DYNAMIC_FTRACE
-ENTRY(ftrace_caller_old)
-       __ftrace_caller _old
-ENDPROC(ftrace_caller_old)
-#endif
-
-#ifdef CONFIG_FUNCTION_GRAPH_TRACER
-ENTRY(ftrace_graph_caller_old)
-       __ftrace_graph_caller
-ENDPROC(ftrace_graph_caller_old)
-#endif
-
-.purgem mcount_enter
-.purgem mcount_get_lr
-.purgem mcount_exit
-#endif
-
 /*
  * __gnu_mcount_nc
  */

diff --git a/arch/arm/kernel/ftrace.c b/arch/arm/kernel/ftrace.c
index ee673c0..bda949f 100644 (file)
--- a/arch/arm/kernel/ftrace.c
+++ b/arch/arm/kernel/ftrace.c
@@ -47,30 +47,6 @@ void arch_ftrace_update_code(int command)
        stop_machine(__ftrace_modify_code, &command, NULL);
 }
 
-#ifdef CONFIG_OLD_MCOUNT
-#define OLD_MCOUNT_ADDR        ((unsigned long) mcount)
-#define OLD_FTRACE_ADDR ((unsigned long) ftrace_caller_old)
-
-#define        OLD_NOP         0xe1a00000      /* mov r0, r0 */
-
-static unsigned long ftrace_nop_replace(struct dyn_ftrace *rec)
-{
-       return rec->arch.old_mcount ? OLD_NOP : NOP;
-}
-
-static unsigned long adjust_address(struct dyn_ftrace *rec, unsigned long addr)
-{
-       if (!rec->arch.old_mcount)
-               return addr;
-
-       if (addr == MCOUNT_ADDR)
-               addr = OLD_MCOUNT_ADDR;
-       else if (addr == FTRACE_ADDR)
-               addr = OLD_FTRACE_ADDR;
-
-       return addr;
-}
-#else
 static unsigned long ftrace_nop_replace(struct dyn_ftrace *rec)
 {
        return NOP;
@@ -80,7 +56,6 @@ static unsigned long adjust_address(struct dyn_ftrace *rec, unsigned long addr)
 {
        return addr;
 }
-#endif
 
 int ftrace_arch_code_modify_prepare(void)
 {
@@ -150,15 +125,6 @@ int ftrace_update_ftrace_func(ftrace_func_t func)
        }
 #endif
 
-#ifdef CONFIG_OLD_MCOUNT
-       if (!ret) {
-               pc = (unsigned long)&ftrace_call_old;
-               new = ftrace_call_replace(pc, (unsigned long)func);
-
-               ret = ftrace_modify_code(pc, 0, new, false);
-       }
-#endif
-
        return ret;
 }
 
@@ -203,16 +169,6 @@ int ftrace_make_nop(struct module *mod,
        new = ftrace_nop_replace(rec);
        ret = ftrace_modify_code(ip, old, new, true);
 
-#ifdef CONFIG_OLD_MCOUNT
-       if (ret == -EINVAL && addr == MCOUNT_ADDR) {
-               rec->arch.old_mcount = true;
-
-               old = ftrace_call_replace(ip, adjust_address(rec, addr));
-               new = ftrace_nop_replace(rec);
-               ret = ftrace_modify_code(ip, old, new, true);
-       }
-#endif
-
        return ret;
 }
 
@@ -275,13 +231,6 @@ static int ftrace_modify_graph_caller(bool enable)
 #endif
 
 
-#ifdef CONFIG_OLD_MCOUNT
-       if (!ret)
-               ret = __ftrace_modify_caller(&ftrace_graph_call_old,
-                                            ftrace_graph_caller_old,
-                                            enable);
-#endif
-
        return ret;
 }