[PATCH/RFC 4/4] add dynamic ftrace support

From: Heiko Carstens
Date: Tue Jun 02 2009 - 07:06:04 EST

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From: Heiko Carstens <heiko.carstens@xxxxxxxxxx>

Dynamic ftrace support for s390.

Signed-off-by: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
---

arch/s390/Kconfig | 2
arch/s390/include/asm/ftrace.h | 19 +++++
arch/s390/include/asm/lowcore.h | 8 +-
arch/s390/kernel/Makefile | 5 +
arch/s390/kernel/early.c | 4 +
arch/s390/kernel/ftrace.c | 132 ++++++++++++++++++++++++++++++++++++++++
arch/s390/kernel/mcount.S | 119 +++++++++++++++++++++++++++---------
arch/s390/kernel/setup.c | 2
arch/s390/kernel/smp.c | 1
scripts/recordmcount.pl | 13 +++
10 files changed, 276 insertions(+), 29 deletions(-)

Index: linux-2.6/arch/s390/include/asm/ftrace.h
===================================================================
--- linux-2.6.orig/arch/s390/include/asm/ftrace.h
+++ linux-2.6/arch/s390/include/asm/ftrace.h
@@ -2,7 +2,26 @@
#define _ASM_S390_FTRACE_H

#ifndef __ASSEMBLY__
+
extern void _mcount(void);
+extern unsigned long ftrace_dyn_func;
+
+struct dyn_arch_ftrace { };
+
+#define MCOUNT_ADDR ((long)_mcount)
+
+#ifdef CONFIG_64BIT
+#define MCOUNT_INSN_SIZE 24
+#define MCOUNT_OFFSET 14
+#else
+#define MCOUNT_INSN_SIZE 30
+#define MCOUNT_OFFSET 8
#endif

+static inline unsigned long ftrace_call_adjust(unsigned long addr)
+{
+ return addr - MCOUNT_OFFSET;
+}
+
+#endif /* __ASSEMBLY__ */
#endif /* _ASM_S390_FTRACE_H */
Index: linux-2.6/arch/s390/include/asm/lowcore.h
===================================================================
--- linux-2.6.orig/arch/s390/include/asm/lowcore.h
+++ linux-2.6/arch/s390/include/asm/lowcore.h
@@ -67,6 +67,7 @@
#define __LC_CPUID 0x02b0
#define __LC_INT_CLOCK 0x02c8
#define __LC_MACHINE_FLAGS 0x02d8
+#define __LC_FTRACE_FUNC 0x02dc
#define __LC_IRB 0x0300
#define __LC_PFAULT_INTPARM 0x0080
#define __LC_CPU_TIMER_SAVE_AREA 0x00d8
@@ -112,6 +113,7 @@
#define __LC_INT_CLOCK 0x0340
#define __LC_VDSO_PER_CPU 0x0350
#define __LC_MACHINE_FLAGS 0x0358
+#define __LC_FTRACE_FUNC 0x0360
#define __LC_IRB 0x0380
#define __LC_PASTE 0x03c0
#define __LC_PFAULT_INTPARM 0x11b8
@@ -280,7 +282,8 @@ struct _lowcore
__u64 int_clock; /* 0x02c8 */
__u64 clock_comparator; /* 0x02d0 */
__u32 machine_flags; /* 0x02d8 */
- __u8 pad_0x02dc[0x0300-0x02dc]; /* 0x02dc */
+ __u32 ftrace_func; /* 0x02dc */
+ __u8 pad_0x02f0[0x0300-0x02f0]; /* 0x02f0 */

/* Interrupt response block */
__u8 irb[64]; /* 0x0300 */
@@ -385,7 +388,8 @@ struct _lowcore
__u64 clock_comparator; /* 0x0348 */
__u64 vdso_per_cpu_data; /* 0x0350 */
__u64 machine_flags; /* 0x0358 */
- __u8 pad_0x0360[0x0380-0x0360]; /* 0x0360 */
+ __u64 ftrace_func; /* 0x0360 */
+ __u8 pad_0x0368[0x0380-0x0368]; /* 0x0368 */

/* Interrupt response block. */
__u8 irb[64]; /* 0x0380 */
Index: linux-2.6/arch/s390/Kconfig
===================================================================
--- linux-2.6.orig/arch/s390/Kconfig
+++ linux-2.6/arch/s390/Kconfig
@@ -82,6 +82,8 @@ config S390
select USE_GENERIC_SMP_HELPERS if SMP
select HAVE_SYSCALL_WRAPPERS
select HAVE_FUNCTION_TRACER
+ select HAVE_FTRACE_MCOUNT_RECORD
+ select HAVE_DYNAMIC_FTRACE
select HAVE_DEFAULT_NO_SPIN_MUTEXES
select HAVE_OPROFILE
select HAVE_KPROBES
Index: linux-2.6/arch/s390/kernel/early.c
===================================================================
--- linux-2.6.orig/arch/s390/kernel/early.c
+++ linux-2.6/arch/s390/kernel/early.c
@@ -11,6 +11,7 @@
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/ctype.h>
+#include <linux/ftrace.h>
#include <linux/lockdep.h>
#include <linux/module.h>
#include <linux/pfn.h>
@@ -410,5 +411,8 @@ void __init startup_init(void)
sclp_facilities_detect();
detect_memory_layout(memory_chunk);
S390_lowcore.machine_flags = machine_flags;
+#ifdef CONFIG_DYNAMIC_FTRACE
+ S390_lowcore.ftrace_func = (unsigned long)ftrace_caller;
+#endif
lockdep_on();
}
Index: linux-2.6/arch/s390/kernel/ftrace.c
===================================================================
--- /dev/null
+++ linux-2.6/arch/s390/kernel/ftrace.c
@@ -0,0 +1,132 @@
+/*
+ * Dynamic function tracer architecture backend.
+ *
+ * Copyright IBM Corp. 2009
+ *
+ * Author(s): Heiko Carstens <heiko.carstens@xxxxxxxxxx>,
+ *
+ */
+
+#include <linux/uaccess.h>
+#include <linux/ftrace.h>
+#include <linux/kernel.h>
+#include <linux/types.h>
+#include <asm/lowcore.h>
+
+void ftrace_disable_code(void);
+void ftrace_call_code(void);
+void ftrace_nop_code(void);
+
+#define FTRACE_INSN_SIZE 4
+
+#ifdef CONFIG_64BIT
+
+asm(
+ " .align 4\n"
+ "ftrace_disable_code:\n"
+ " j 0f\n"
+ " .word 0x0024\n"
+ " lg %r1,"__stringify(__LC_FTRACE_FUNC)"\n"
+ " basr %r14,%r1\n"
+ " lg %r14,8(15)\n"
+ " lgr %r0,%r0\n"
+ "0:\n");
+
+asm(
+ " .align 4\n"
+ "ftrace_nop_code:\n"
+ " j .+"__stringify(MCOUNT_INSN_SIZE)"\n");
+
+asm(
+ " .align 4\n"
+ "ftrace_call_code:\n"
+ " stg %r14,8(%r15)\n");
+
+#else /* CONFIG_64BIT */
+
+asm(
+ " .align 4\n"
+ "ftrace_disable_code:\n"
+ " j 0f\n"
+ " l %r1,"__stringify(__LC_FTRACE_FUNC)"\n"
+ " basr %r14,%r1\n"
+ " l %r14,4(%r15)\n"
+ " j 0f\n"
+ " bcr 0,%r7\n"
+ " bcr 0,%r7\n"
+ " bcr 0,%r7\n"
+ " bcr 0,%r7\n"
+ " bcr 0,%r7\n"
+ " bcr 0,%r7\n"
+ "0:\n");
+
+asm(
+ " .align 4\n"
+ "ftrace_nop_code:\n"
+ " j .+"__stringify(MCOUNT_INSN_SIZE)"\n");
+
+asm(
+ " .align 4\n"
+ "ftrace_call_code:\n"
+ " st %r14,4(%r15)\n");
+
+#endif /* CONFIG_64BIT */
+
+static int ftrace_modify_code(unsigned long ip,
+ void *old_code, int old_size,
+ void *new_code, int new_size)
+{
+ unsigned char replaced[MCOUNT_INSN_SIZE];
+
+ /*
+ * Note: Due to modules code can disappear and change.
+ * We need to protect against faulting as well as code
+ * changing. We do this by using the probe_kernel_*
+ * functions.
+ * This however is just a simple sanity check.
+ */
+ if (probe_kernel_read(replaced, (void *)ip, old_size))
+ return -EFAULT;
+ if (memcmp(replaced, old_code, old_size) != 0)
+ return -EINVAL;
+ if (probe_kernel_write((void *)ip, new_code, new_size))
+ return -EPERM;
+ return 0;
+}
+
+static int ftrace_make_initial_nop(struct module *mod, struct dyn_ftrace *rec,
+ unsigned long addr)
+{
+ return ftrace_modify_code(rec->ip,
+ ftrace_call_code, FTRACE_INSN_SIZE,
+ ftrace_disable_code, MCOUNT_INSN_SIZE);
+}
+
+int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec,
+ unsigned long addr)
+{
+ if (addr == MCOUNT_ADDR)
+ return ftrace_make_initial_nop(mod, rec, addr);
+ return ftrace_modify_code(rec->ip,
+ ftrace_call_code, FTRACE_INSN_SIZE,
+ ftrace_nop_code, FTRACE_INSN_SIZE);
+}
+
+int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
+{
+ return ftrace_modify_code(rec->ip,
+ ftrace_nop_code, FTRACE_INSN_SIZE,
+ ftrace_call_code, FTRACE_INSN_SIZE);
+}
+
+int ftrace_update_ftrace_func(ftrace_func_t func)
+{
+ ftrace_dyn_func = (unsigned long)func;
+ return 0;
+}
+
+int __init ftrace_dyn_arch_init(void *data)
+{
+ *(unsigned long *)data = 0;
+ return 0;
+}
Index: linux-2.6/arch/s390/kernel/Makefile
===================================================================
--- linux-2.6.orig/arch/s390/kernel/Makefile
+++ linux-2.6/arch/s390/kernel/Makefile
@@ -7,6 +7,10 @@ ifdef CONFIG_FUNCTION_TRACER
CFLAGS_REMOVE_early.o = -pg
endif

+ifdef CONFIG_DYNAMIC_FTRACE
+CFLAGS_REMOVE_ftrace.o = -pg
+endif
+
#
# Passing null pointers is ok for smp code, since we access the lowcore here.
#
@@ -41,6 +45,7 @@ obj-$(CONFIG_COMPAT) += compat_linux.o
obj-$(CONFIG_STACKTRACE) += stacktrace.o
obj-$(CONFIG_KPROBES) += kprobes.o
obj-$(CONFIG_FUNCTION_TRACER) += mcount.o
+obj-$(CONFIG_DYNAMIC_FTRACE) += ftrace.o

# Kexec part
S390_KEXEC_OBJS := machine_kexec.o crash.o
Index: linux-2.6/arch/s390/kernel/mcount.S
===================================================================
--- linux-2.6.orig/arch/s390/kernel/mcount.S
+++ linux-2.6/arch/s390/kernel/mcount.S
@@ -1,5 +1,5 @@
/*
- * Copyright IBM Corp. 2008
+ * Copyright IBM Corp. 2008,2009
*
* Author(s): Heiko Carstens <heiko.carstens@xxxxxxxxxx>,
*
@@ -7,36 +7,46 @@

#include <asm/asm-offsets.h>

-#ifndef CONFIG_64BIT
-.globl _mcount
+ .globl ftrace_stub
+ftrace_stub:
+ br %r14
+
+#ifdef CONFIG_64BIT
+
+#ifdef CONFIG_DYNAMIC_FTRACE
+
+ .globl _mcount
_mcount:
- stm %r0,%r5,8(%r15)
- st %r14,56(%r15)
- lr %r1,%r15
- ahi %r15,-96
- l %r3,100(%r15)
- la %r2,0(%r14)
- st %r1,__SF_BACKCHAIN(%r15)
- la %r3,0(%r3)
- bras %r14,0f
- .long ftrace_trace_function
-0: l %r14,0(%r14)
- l %r14,0(%r14)
- basr %r14,%r14
- ahi %r15,96
- lm %r0,%r5,8(%r15)
- l %r14,56(%r15)
br %r14

-.globl ftrace_stub
-ftrace_stub:
+ .globl ftrace_caller
+ftrace_caller:
+ stmg %r2,%r5,32(%r15)
+ stg %r14,112(%r15)
+ lgr %r1,%r15
+ aghi %r15,-160
+ stg %r1,__SF_BACKCHAIN(%r15)
+ lgr %r2,%r14
+ lg %r3,168(%r15)
+ larl %r14,ftrace_dyn_func
+ lg %r14,0(%r14)
+ basr %r14,%r14
+ aghi %r15,160
+ lmg %r2,%r5,32(%r15)
+ lg %r14,112(%r15)
br %r14

-#else /* CONFIG_64BIT */
+ .data
+ .globl ftrace_dyn_func
+ftrace_dyn_func:
+ .quad ftrace_stub
+ .previous
+
+#else /* CONFIG_DYNAMIC_FTRACE */

-.globl _mcount
+ .globl _mcount
_mcount:
- stmg %r0,%r5,16(%r15)
+ stmg %r2,%r5,32(%r15)
stg %r14,112(%r15)
lgr %r1,%r15
aghi %r15,-160
@@ -47,12 +57,67 @@ _mcount:
lg %r14,0(%r14)
basr %r14,%r14
aghi %r15,160
- lmg %r0,%r5,16(%r15)
+ lmg %r2,%r5,32(%r15)
lg %r14,112(%r15)
br %r14

-.globl ftrace_stub
-ftrace_stub:
+#endif /* CONFIG_DYNAMIC_FTRACE */
+
+#else /* CONFIG_64BIT */
+
+#ifdef CONFIG_DYNAMIC_FTRACE
+
+ .globl _mcount
+_mcount:
+ br %r14
+
+ .globl ftrace_caller
+ftrace_caller:
+ stm %r2,%r5,16(%r15)
+ st %r14,56(%r15)
+ lr %r1,%r15
+ ahi %r15,-96
+ l %r3,100(%r15)
+ la %r2,0(%r14)
+ st %r1,__SF_BACKCHAIN(%r15)
+ la %r3,0(%r3)
+ bras %r14,0f
+ .long ftrace_dyn_func
+0: l %r14,0(%r14)
+ l %r14,0(%r14)
+ basr %r14,%r14
+ ahi %r15,96
+ lm %r2,%r5,16(%r15)
+ l %r14,56(%r15)
+ br %r14
+
+ .data
+ .globl ftrace_dyn_func
+ftrace_dyn_func:
+ .long ftrace_stub
+ .previous
+
+#else /* CONFIG_DYNAMIC_FTRACE */
+
+ .globl _mcount
+_mcount:
+ stm %r2,%r5,16(%r15)
+ st %r14,56(%r15)
+ lr %r1,%r15
+ ahi %r15,-96
+ l %r3,100(%r15)
+ la %r2,0(%r14)
+ st %r1,__SF_BACKCHAIN(%r15)
+ la %r3,0(%r3)
+ bras %r14,0f
+ .long ftrace_trace_function
+0: l %r14,0(%r14)
+ l %r14,0(%r14)
+ basr %r14,%r14
+ ahi %r15,96
+ lm %r2,%r5,16(%r15)
+ l %r14,56(%r15)
br %r14

+#endif /* CONFIG_DYNAMIC_FTRACE */
#endif /* CONFIG_64BIT */
Index: linux-2.6/arch/s390/kernel/setup.c
===================================================================
--- linux-2.6.orig/arch/s390/kernel/setup.c
+++ linux-2.6/arch/s390/kernel/setup.c
@@ -42,6 +42,7 @@
#include <linux/ctype.h>
#include <linux/reboot.h>
#include <linux/topology.h>
+#include <linux/ftrace.h>

#include <asm/ipl.h>
#include <asm/uaccess.h>
@@ -442,6 +443,7 @@ setup_lowcore(void)
lc->steal_timer = S390_lowcore.steal_timer;
lc->last_update_timer = S390_lowcore.last_update_timer;
lc->last_update_clock = S390_lowcore.last_update_clock;
+ lc->ftrace_func = S390_lowcore.ftrace_func;
set_prefix((u32)(unsigned long) lc);
lowcore_ptr[0] = lc;
}
Index: linux-2.6/arch/s390/kernel/smp.c
===================================================================
--- linux-2.6.orig/arch/s390/kernel/smp.c
+++ linux-2.6/arch/s390/kernel/smp.c
@@ -572,6 +572,7 @@ int __cpuinit __cpu_up(unsigned int cpu)
cpu_lowcore->cpu_nr = cpu;
cpu_lowcore->kernel_asce = S390_lowcore.kernel_asce;
cpu_lowcore->machine_flags = S390_lowcore.machine_flags;
+ cpu_lowcore->ftrace_func = S390_lowcore.ftrace_func;
eieio();

while (signal_processor(cpu, sigp_restart) == sigp_busy)
Index: linux-2.6/scripts/recordmcount.pl
===================================================================
--- linux-2.6.orig/scripts/recordmcount.pl
+++ linux-2.6/scripts/recordmcount.pl
@@ -185,6 +185,19 @@ if ($arch eq "x86_64") {
$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\$";
+ $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\$";
+ $alignment = 8;
+ $type = ".quad";
+ $ld .= " -m elf64_s390";
+ $cc .= " -m64";
+
} elsif ($arch eq "sh") {
$alignment = 2;

--
--
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Next message: Paul Mackerras: "[PATCH] perf_counter: Initialize per-cpu context earlier on cpu up"
Previous message: Heiko Carstens: "[PATCH/RFC 1/4] maccess: add weak attribute to probe_kernel_write"
In reply to: Heiko Carstens: "[PATCH/RFC 1/4] maccess: add weak attribute to probe_kernel_write"
Next in thread: Steven Rostedt: "Re: [PATCH/RFC 4/4] add dynamic ftrace support"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]