This is a note to let you know that I've just added the patch titled
ARM: 8788/1: ftrace: remove old mcount support
to the 4.19-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
arm-8788-1-ftrace-remove-old-mcount-support.patch
and it can be found in the queue-4.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 1c6725897788e5e78c35af3b16b910dfedd79b8d
Author: Stefan Agner <stefan@xxxxxxxx>
Date: Tue Sep 11 04:31:49 2018 +0100
ARM: 8788/1: ftrace: remove old mcount support
commit d3c61619568c88d48eccd5e74b4f84faa1440652 upstream.
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@xxxxxxxx>
Signed-off-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxx>
Signed-off-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/arm/Kconfig.debug b/arch/arm/Kconfig.debug
index bee0ba1d1cfb..631ad56fd9a8 100644
--- 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 9e842ff41768..18b0197f2384 100644
--- 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 783fbb4de5f9..8fa2dc21d332 100644
--- 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 efcd9f25a14b..0be69e551a64 100644
--- 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 ee673c09aa6c..bda949fd84e8 100644
--- 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;
}
