s390/ftrace: remove 31 bit ftrace support

31 bit and 64 bit diverge more and more and it is rather painful
to keep both parts running.
To make things simpler just remove the 31 bit support which nobody
uses anyway.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/Kconfig

@@ -117,11 +117,11 @@ config S390
 	select HAVE_CMPXCHG_LOCAL
 	select HAVE_C_RECORDMCOUNT
 	select HAVE_DEBUG_KMEMLEAK
-	select HAVE_DYNAMIC_FTRACE
+	select HAVE_DYNAMIC_FTRACE if 64BIT
 	select HAVE_DYNAMIC_FTRACE_WITH_REGS if 64BIT
 	select HAVE_FTRACE_MCOUNT_RECORD
-	select HAVE_FUNCTION_GRAPH_TRACER
-	select HAVE_FUNCTION_TRACER
+	select HAVE_FUNCTION_GRAPH_TRACER if 64BIT
+	select HAVE_FUNCTION_TRACER if 64BIT
 	select HAVE_FUTEX_CMPXCHG if FUTEX
 	select HAVE_KERNEL_BZIP2
 	select HAVE_KERNEL_GZIP

arch/s390/include/asm/ftrace.h

@@ -18,14 +18,8 @@ static inline unsigned long ftrace_call_adjust(unsigned long addr)
 
 #endif /* __ASSEMBLY__ */
 
-#ifdef CONFIG_64BIT
 #define MCOUNT_INSN_SIZE  18
-#else
-#define MCOUNT_INSN_SIZE  22
-#endif
 
-#ifdef CONFIG_64BIT
 #define ARCH_SUPPORTS_FTRACE_OPS 1
-#endif
 
 #endif /* _ASM_S390_FTRACE_H */

arch/s390/kernel/Makefile

@@ -52,8 +52,7 @@ obj-$(CONFIG_COMPAT)		+= compat_wrapper.o $(compat-obj-y)
 
 obj-$(CONFIG_STACKTRACE)	+= stacktrace.o
 obj-$(CONFIG_KPROBES)		+= kprobes.o
-obj-$(CONFIG_FUNCTION_TRACER)	+= $(if $(CONFIG_64BIT),mcount64.o,mcount.o)
-obj-$(CONFIG_FUNCTION_TRACER)	+= ftrace.o
+obj-$(CONFIG_FUNCTION_TRACER)	+= mcount.o ftrace.o
 obj-$(CONFIG_CRASH_DUMP)	+= crash_dump.o
 obj-$(CONFIG_UPROBES)		+= uprobes.o
 

arch/s390/kernel/ftrace.c

@@ -21,9 +21,8 @@ void mcount_replace_code(void);
 void ftrace_disable_code(void);
 void ftrace_enable_insn(void);
 
-#ifdef CONFIG_64BIT
 /*
- * The 64-bit mcount code looks like this:
+ * The mcount code looks like this:
  *	stg	%r14,8(%r15)		# offset 0
  *	larl	%r1,<&counter>		# offset 6
  *	brasl	%r14,_mcount		# offset 12
@@ -34,7 +33,7 @@ void ftrace_enable_insn(void);
  * Note: we do not patch the first instruction to an unconditional branch,
  * since that would break kprobes/jprobes. It is easier to leave the larl
  * instruction in and only modify the second instruction.
- * The 64-bit enabled ftrace code block looks like this:
+ * The enabled ftrace code block looks like this:
  *	larl	%r0,.+24		# offset 0
  * >	lg	%r1,__LC_FTRACE_FUNC	# offset 6
  *	br	%r1			# offset 12
@@ -71,65 +70,15 @@ asm(
 #define MCOUNT_INSN_OFFSET	6
 #define FTRACE_INSN_SIZE	6
 
-#else /* CONFIG_64BIT */
-/*
- * The 31-bit mcount code looks like this:
- *	st	%r14,4(%r15)		# offset 0
- * >	bras	%r1,0f			# offset 4
- * >	.long	_mcount			# offset 8
- * >	.long	<&counter>		# offset 12
- * > 0:	l	%r14,0(%r1)		# offset 16
- * >	l	%r1,4(%r1)		# offset 20
- *	basr	%r14,%r14		# offset 24
- *	l	%r14,4(%r15)		# offset 26
- * Total length is 30 bytes. The twenty bytes starting from offset 4
- * to offset 24 get overwritten by ftrace_make_nop / ftrace_make_call.
- * The 31-bit enabled ftrace code block looks like this:
- *	st	%r14,4(%r15)		# offset 0
- * >	l	%r14,__LC_FTRACE_FUNC	# offset 4
- * >	j	0f			# offset 8
- * >	.fill	12,1,0x07		# offset 12
- *   0:	basr	%r14,%r14		# offset 24
- *	l	%r14,4(%r14)		# offset 26
- * The return points of the mcount/ftrace function have the same offset 26.
- * The 31-bit disabled ftrace code block looks like this:
- *	st	%r14,4(%r15)		# offset 0
- * >	j	.+26			# offset 4
- * >	j	0f			# offset 8
- * >	.fill	12,1,0x07		# offset 12
- *   0:	basr	%r14,%r14		# offset 24
- *	l	%r14,4(%r14)		# offset 26
- * The j instruction branches to offset 30 to skip as many instructions
- * as possible.
- */
-asm(
-	"	.align	4\n"
-	"ftrace_disable_code:\n"
-	"	j	1f\n"
-	"	j	0f\n"
-	"	.fill	12,1,0x07\n"
-	"0:	basr	%r14,%r14\n"
-	"1:\n"
-	"	.align	4\n"
-	"ftrace_enable_insn:\n"
-	"	l	%r14,"__stringify(__LC_FTRACE_FUNC)"\n");
-
-#define FTRACE_INSN_SIZE	4
-
-#endif /* CONFIG_64BIT */
-
-#ifdef CONFIG_64BIT
 int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
 		       unsigned long addr)
 {
 	return 0;
 }
-#endif
 
 int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec,
 		    unsigned long addr)
 {
-#ifdef CONFIG_64BIT
 	/* Initial replacement of the whole mcount block */
 	if (addr == MCOUNT_ADDR) {
 		if (probe_kernel_write((void *) rec->ip - MCOUNT_INSN_OFFSET,
@@ -138,7 +87,6 @@ int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec,
 			return -EPERM;
 		return 0;
 	}
-#endif
 	if (probe_kernel_write((void *) rec->ip, ftrace_disable_code,
 			       MCOUNT_INSN_SIZE))
 		return -EPERM;
@@ -196,8 +144,6 @@ unsigned long __kprobes prepare_ftrace_return(unsigned long parent,
  * the original offset to prepare_ftrace_return and put it back.
  */
 
-#ifdef CONFIG_64BIT
-
 int ftrace_enable_ftrace_graph_caller(void)
 {
 	static unsigned short offset = 0x0002;
@@ -216,25 +162,4 @@ int ftrace_disable_ftrace_graph_caller(void)
 				  &offset, sizeof(offset));
 }
 
-#else /* CONFIG_64BIT */
-
-int ftrace_enable_ftrace_graph_caller(void)
-{
-	unsigned short offset;
-
-	offset = ((void *) prepare_ftrace_return -
-		  (void *) ftrace_graph_caller) / 2;
-	return probe_kernel_write((void *) ftrace_graph_caller + 2,
-				  &offset, sizeof(offset));
-}
-
-int ftrace_disable_ftrace_graph_caller(void)
-{
-	static unsigned short offset = 0x0002;
-
-	return probe_kernel_write((void *) ftrace_graph_caller + 2,
-				  &offset, sizeof(offset));
-}
-
-#endif /* CONFIG_64BIT */
 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */

arch/s390/kernel/mcount.S

@@ -8,60 +8,73 @@
 #include <linux/linkage.h>
 #include <asm/asm-offsets.h>
 #include <asm/ftrace.h>
+#include <asm/ptrace.h>
 
 	.section .kprobes.text, "ax"
 
 ENTRY(ftrace_stub)
 	br	%r14
 
+#define STACK_FRAME_SIZE  (STACK_FRAME_OVERHEAD + __PT_SIZE)
+#define STACK_PTREGS	  (STACK_FRAME_OVERHEAD)
+#define STACK_PTREGS_GPRS (STACK_PTREGS + __PT_GPRS)
+#define STACK_PTREGS_PSW  (STACK_PTREGS + __PT_PSW)
+
 ENTRY(_mcount)
 	br	%r14
 
 ENTRY(ftrace_caller)
-	stm	%r2,%r5,16(%r15)
-	bras	%r1,1f
-0:	.long	ftrace_trace_function
-1:	st	%r14,56(%r15)
-	lr	%r0,%r15
-	ahi	%r15,-96
-	l	%r3,100(%r15)
-	la	%r2,0(%r14)
-	st	%r0,__SF_BACKCHAIN(%r15)
-	la	%r3,0(%r3)
-	ahi	%r2,-MCOUNT_INSN_SIZE
-	l	%r14,0b-0b(%r1)
-	l	%r14,0(%r14)
-	basr	%r14,%r14
+	.globl	ftrace_regs_caller
+	.set	ftrace_regs_caller,ftrace_caller
+	lgr	%r1,%r15
+	aghi	%r15,-STACK_FRAME_SIZE
+	stg	%r1,__SF_BACKCHAIN(%r15)
+	stg	%r1,(STACK_PTREGS_GPRS+15*8)(%r15)
+	stg	%r0,(STACK_PTREGS_PSW+8)(%r15)
+	stmg	%r2,%r14,(STACK_PTREGS_GPRS+2*8)(%r15)
+#ifdef CONFIG_HAVE_MARCH_Z196_FEATURES
+	aghik	%r2,%r0,-MCOUNT_INSN_SIZE
+	lgrl	%r4,function_trace_op
+	lgrl	%r1,ftrace_trace_function
+#else
+	lgr	%r2,%r0
+	aghi	%r2,-MCOUNT_INSN_SIZE
+	larl	%r4,function_trace_op
+	lg	%r4,0(%r4)
+	larl	%r1,ftrace_trace_function
+	lg	%r1,0(%r1)
+#endif
+	lgr	%r3,%r14
+	la	%r5,STACK_PTREGS(%r15)
+	basr	%r14,%r1
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
-	l	%r2,100(%r15)
-	l	%r3,152(%r15)
-ENTRY(ftrace_graph_caller)
-# The bras instruction gets runtime patched to call prepare_ftrace_return.
+# The j instruction gets runtime patched to a nop instruction.
 # See ftrace_enable_ftrace_graph_caller. The patched instruction is:
-#	bras	%r14,prepare_ftrace_return
-	bras	%r14,0f
-0:	st	%r2,100(%r15)
+#	j	.+4
+ENTRY(ftrace_graph_caller)
+	j	ftrace_graph_caller_end
+	lg	%r2,(STACK_PTREGS_GPRS+14*8)(%r15)
+	lg	%r3,(STACK_PTREGS_PSW+8)(%r15)
+	brasl	%r14,prepare_ftrace_return
+	stg	%r2,(STACK_PTREGS_GPRS+14*8)(%r15)
+ftrace_graph_caller_end:
+	.globl	ftrace_graph_caller_end
 #endif
-	ahi	%r15,96
-	l	%r14,56(%r15)
-	lm	%r2,%r5,16(%r15)
-	br	%r14
+	lg	%r1,(STACK_PTREGS_PSW+8)(%r15)
+	lmg	%r2,%r15,(STACK_PTREGS_GPRS+2*8)(%r15)
+	br	%r1
 
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 
 ENTRY(return_to_handler)
-	stm	%r2,%r5,16(%r15)
-	st	%r14,56(%r15)
-	lr	%r0,%r15
-	ahi	%r15,-96
-	st	%r0,__SF_BACKCHAIN(%r15)
-	bras	%r1,0f
-	.long	ftrace_return_to_handler
-0:	l	%r2,0b-0b(%r1)
-	basr	%r14,%r2
-	lr	%r14,%r2
-	ahi	%r15,96
-	lm	%r2,%r5,16(%r15)
+	stmg	%r2,%r5,32(%r15)
+	lgr	%r1,%r15
+	aghi	%r15,-STACK_FRAME_OVERHEAD
+	stg	%r1,__SF_BACKCHAIN(%r15)
+	brasl	%r14,ftrace_return_to_handler
+	aghi	%r15,STACK_FRAME_OVERHEAD
+	lgr	%r14,%r2
+	lmg	%r2,%r5,32(%r15)
 	br	%r14
 
 #endif

scripts/recordmcount.c

@@ -388,10 +388,6 @@ do_file(char const *const fname)
 				"unrecognized ET_REL file: %s\n", fname);
 			fail_file();
 		}
-		if (w2(ehdr->e_machine) == EM_S390) {
-			reltype = R_390_32;
-			mcount_adjust_32 = -4;
-		}
 		if (w2(ehdr->e_machine) == EM_MIPS) {
 			reltype = R_MIPS_32;
 			is_fake_mcount32 = MIPS32_is_fake_mcount;

scripts/recordmcount.pl

@@ -241,13 +241,6 @@ sub check_objcopy
     $objcopy .= " -O elf32-i386";
     $cc .= " -m32";
 
-} elsif ($arch eq "s390" && $bits == 32) {
-    $mcount_regex = "^\\s*([0-9a-fA-F]+):\\s*R_390_32\\s+_mcount\$";
-    $mcount_adjust = -4;
-    $alignment = 4;
-    $ld .= " -m elf_s390";
-    $cc .= " -m31";
-
 } elsif ($arch eq "s390" && $bits == 64) {
     $mcount_regex = "^\\s*([0-9a-fA-F]+):\\s*R_390_(PC|PLT)32DBL\\s+_mcount\\+0x2\$";
     $mcount_adjust = -8;