aboutsummaryrefslogtreecommitdiffstats
path: root/arch/ia64/kernel
diff options
context:
space:
mode:
authorShaohua Li <shaohua.li@intel.com>2009-01-08 22:29:49 -0500
committerIngo Molnar <mingo@elte.hu>2009-01-14 06:11:31 -0500
commita14a07b8018b714e03a39ff2180c66e307ef4238 (patch)
tree7c4b9249f862969b80b74e5e11e56480b0e3d15c /arch/ia64/kernel
parentd3e75ff14bc1453c4762428395aac9953a023efc (diff)
ftrace, ia64: IA64 dynamic ftrace support
IA64 dynamic ftrace support. The original _mcount stub for each function is like: alloc r40=ar.pfs,12,8,0 mov r43=r0;; mov r42=b0 mov r41=r1 nop.i 0x0 br.call.sptk.many b0 = _mcount;; The patch convert it to below for nop: [MII] nop.m 0x0 mov r3=ip nop.i 0x0 [MLX] nop.m 0x0 nop.x 0x0;; This isn't completely nop, as there is one instuction 'mov r3=ip', but it should be light and harmless for code follow it. And below is for call [MII] nop.m 0x0 mov r3=ip nop.i 0x0 [MLX] nop.m 0x0 brl.many .;; In this way, only one instruction is changed to convert code between nop and call. This should meet dyn-ftrace's requirement. But this requires CPU support brl instruction, so dyn-ftrace isn't supported for old Itanium system. Assume there are quite few such old system running. Signed-off-by: Shaohua Li <shaohua.li@intel.com> Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/ia64/kernel')
-rw-r--r--arch/ia64/kernel/Makefile5
-rw-r--r--arch/ia64/kernel/entry.S51
-rw-r--r--arch/ia64/kernel/ftrace.c206
3 files changed, 262 insertions, 0 deletions
diff --git a/arch/ia64/kernel/Makefile b/arch/ia64/kernel/Makefile
index c381ea954892..ab6e7ec0bba3 100644
--- a/arch/ia64/kernel/Makefile
+++ b/arch/ia64/kernel/Makefile
@@ -2,6 +2,10 @@
2# Makefile for the linux kernel. 2# Makefile for the linux kernel.
3# 3#
4 4
5ifdef CONFIG_DYNAMIC_FTRACE
6CFLAGS_REMOVE_ftrace.o = -pg
7endif
8
5extra-y := head.o init_task.o vmlinux.lds 9extra-y := head.o init_task.o vmlinux.lds
6 10
7obj-y := acpi.o entry.o efi.o efi_stub.o gate-data.o fsys.o ia64_ksyms.o irq.o irq_ia64.o \ 11obj-y := acpi.o entry.o efi.o efi_stub.o gate-data.o fsys.o ia64_ksyms.o irq.o irq_ia64.o \
@@ -28,6 +32,7 @@ obj-$(CONFIG_IA64_CYCLONE) += cyclone.o
28obj-$(CONFIG_CPU_FREQ) += cpufreq/ 32obj-$(CONFIG_CPU_FREQ) += cpufreq/
29obj-$(CONFIG_IA64_MCA_RECOVERY) += mca_recovery.o 33obj-$(CONFIG_IA64_MCA_RECOVERY) += mca_recovery.o
30obj-$(CONFIG_KPROBES) += kprobes.o jprobes.o 34obj-$(CONFIG_KPROBES) += kprobes.o jprobes.o
35obj-$(CONFIG_DYNAMIC_FTRACE) += ftrace.o
31obj-$(CONFIG_KEXEC) += machine_kexec.o relocate_kernel.o crash.o 36obj-$(CONFIG_KEXEC) += machine_kexec.o relocate_kernel.o crash.o
32obj-$(CONFIG_CRASH_DUMP) += crash_dump.o 37obj-$(CONFIG_CRASH_DUMP) += crash_dump.o
33obj-$(CONFIG_IA64_UNCACHED_ALLOCATOR) += uncached.o 38obj-$(CONFIG_IA64_UNCACHED_ALLOCATOR) += uncached.o
diff --git a/arch/ia64/kernel/entry.S b/arch/ia64/kernel/entry.S
index c2f7d798e2a5..e0be92a6abb0 100644
--- a/arch/ia64/kernel/entry.S
+++ b/arch/ia64/kernel/entry.S
@@ -1406,6 +1406,56 @@ GLOBAL_ENTRY(unw_init_running)
1406END(unw_init_running) 1406END(unw_init_running)
1407 1407
1408#ifdef CONFIG_FUNCTION_TRACER 1408#ifdef CONFIG_FUNCTION_TRACER
1409#ifdef CONFIG_DYNAMIC_FTRACE
1410GLOBAL_ENTRY(_mcount)
1411 br ftrace_stub
1412END(_mcount)
1413
1414.here:
1415 br.ret.sptk.many b0
1416
1417GLOBAL_ENTRY(ftrace_caller)
1418 alloc out0 = ar.pfs, 8, 0, 4, 0
1419 mov out3 = r0
1420 ;;
1421 mov out2 = b0
1422 add r3 = 0x20, r3
1423 mov out1 = r1;
1424 br.call.sptk.many b0 = ftrace_patch_gp
1425 //this might be called from module, so we must patch gp
1426ftrace_patch_gp:
1427 movl gp=__gp
1428 mov b0 = r3
1429 ;;
1430.global ftrace_call;
1431ftrace_call:
1432{
1433 .mlx
1434 nop.m 0x0
1435 movl r3 = .here;;
1436}
1437 alloc loc0 = ar.pfs, 4, 4, 2, 0
1438 ;;
1439 mov loc1 = b0
1440 mov out0 = b0
1441 mov loc2 = r8
1442 mov loc3 = r15
1443 ;;
1444 adds out0 = -MCOUNT_INSN_SIZE, out0
1445 mov out1 = in2
1446 mov b6 = r3
1447
1448 br.call.sptk.many b0 = b6
1449 ;;
1450 mov ar.pfs = loc0
1451 mov b0 = loc1
1452 mov r8 = loc2
1453 mov r15 = loc3
1454 br ftrace_stub
1455 ;;
1456END(ftrace_caller)
1457
1458#else
1409GLOBAL_ENTRY(_mcount) 1459GLOBAL_ENTRY(_mcount)
1410 movl r2 = ftrace_stub 1460 movl r2 = ftrace_stub
1411 movl r3 = ftrace_trace_function;; 1461 movl r3 = ftrace_trace_function;;
@@ -1435,6 +1485,7 @@ GLOBAL_ENTRY(_mcount)
1435 br ftrace_stub 1485 br ftrace_stub
1436 ;; 1486 ;;
1437END(_mcount) 1487END(_mcount)
1488#endif
1438 1489
1439GLOBAL_ENTRY(ftrace_stub) 1490GLOBAL_ENTRY(ftrace_stub)
1440 mov r3 = b0 1491 mov r3 = b0
diff --git a/arch/ia64/kernel/ftrace.c b/arch/ia64/kernel/ftrace.c
new file mode 100644
index 000000000000..7fc8c961b1f7
--- /dev/null
+++ b/arch/ia64/kernel/ftrace.c
@@ -0,0 +1,206 @@
1/*
2 * Dynamic function tracing support.
3 *
4 * Copyright (C) 2008 Shaohua Li <shaohua.li@intel.com>
5 *
6 * For licencing details, see COPYING.
7 *
8 * Defines low-level handling of mcount calls when the kernel
9 * is compiled with the -pg flag. When using dynamic ftrace, the
10 * mcount call-sites get patched lazily with NOP till they are
11 * enabled. All code mutation routines here take effect atomically.
12 */
13
14#include <linux/uaccess.h>
15#include <linux/ftrace.h>
16
17#include <asm/cacheflush.h>
18#include <asm/patch.h>
19
20/* In IA64, each function will be added below two bundles with -pg option */
21static unsigned char __attribute__((aligned(8)))
22ftrace_orig_code[MCOUNT_INSN_SIZE] = {
23 0x02, 0x40, 0x31, 0x10, 0x80, 0x05, /* alloc r40=ar.pfs,12,8,0 */
24 0xb0, 0x02, 0x00, 0x00, 0x42, 0x40, /* mov r43=r0;; */
25 0x05, 0x00, 0xc4, 0x00, /* mov r42=b0 */
26 0x11, 0x48, 0x01, 0x02, 0x00, 0x21, /* mov r41=r1 */
27 0x00, 0x00, 0x00, 0x02, 0x00, 0x00, /* nop.i 0x0 */
28 0x08, 0x00, 0x00, 0x50 /* br.call.sptk.many b0 = _mcount;; */
29};
30
31struct ftrace_orig_insn {
32 u64 dummy1, dummy2, dummy3;
33 u64 dummy4:64-41+13;
34 u64 imm20:20;
35 u64 dummy5:3;
36 u64 sign:1;
37 u64 dummy6:4;
38};
39
40/* mcount stub will be converted below for nop */
41static unsigned char ftrace_nop_code[MCOUNT_INSN_SIZE] = {
42 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, /* [MII] nop.m 0x0 */
43 0x30, 0x00, 0x00, 0x60, 0x00, 0x00, /* mov r3=ip */
44 0x00, 0x00, 0x04, 0x00, /* nop.i 0x0 */
45 0x05, 0x00, 0x00, 0x00, 0x01, 0x00, /* [MLX] nop.m 0x0 */
46 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* nop.x 0x0;; */
47 0x00, 0x00, 0x04, 0x00
48};
49
50static unsigned char *ftrace_nop_replace(void)
51{
52 return ftrace_nop_code;
53}
54
55/*
56 * mcount stub will be converted below for call
57 * Note: Just the last instruction is changed against nop
58 * */
59static unsigned char __attribute__((aligned(8)))
60ftrace_call_code[MCOUNT_INSN_SIZE] = {
61 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, /* [MII] nop.m 0x0 */
62 0x30, 0x00, 0x00, 0x60, 0x00, 0x00, /* mov r3=ip */
63 0x00, 0x00, 0x04, 0x00, /* nop.i 0x0 */
64 0x05, 0x00, 0x00, 0x00, 0x01, 0x00, /* [MLX] nop.m 0x0 */
65 0xff, 0xff, 0xff, 0xff, 0x7f, 0x00, /* brl.many .;;*/
66 0xf8, 0xff, 0xff, 0xc8
67};
68
69struct ftrace_call_insn {
70 u64 dummy1, dummy2;
71 u64 dummy3:48;
72 u64 imm39_l:16;
73 u64 imm39_h:23;
74 u64 dummy4:13;
75 u64 imm20:20;
76 u64 dummy5:3;
77 u64 i:1;
78 u64 dummy6:4;
79};
80
81static unsigned char *ftrace_call_replace(unsigned long ip, unsigned long addr)
82{
83 struct ftrace_call_insn *code = (void *)ftrace_call_code;
84 unsigned long offset = addr - (ip + 0x10);
85
86 code->imm39_l = offset >> 24;
87 code->imm39_h = offset >> 40;
88 code->imm20 = offset >> 4;
89 code->i = offset >> 63;
90 return ftrace_call_code;
91}
92
93static int
94ftrace_modify_code(unsigned long ip, unsigned char *old_code,
95 unsigned char *new_code, int do_check)
96{
97 unsigned char replaced[MCOUNT_INSN_SIZE];
98
99 /*
100 * Note: Due to modules and __init, code can
101 * disappear and change, we need to protect against faulting
102 * as well as code changing. We do this by using the
103 * probe_kernel_* functions.
104 *
105 * No real locking needed, this code is run through
106 * kstop_machine, or before SMP starts.
107 */
108
109 if (!do_check)
110 goto skip_check;
111
112 /* read the text we want to modify */
113 if (probe_kernel_read(replaced, (void *)ip, MCOUNT_INSN_SIZE))
114 return -EFAULT;
115
116 /* Make sure it is what we expect it to be */
117 if (memcmp(replaced, old_code, MCOUNT_INSN_SIZE) != 0)
118 return -EINVAL;
119
120skip_check:
121 /* replace the text with the new text */
122 if (probe_kernel_write(((void *)ip), new_code, MCOUNT_INSN_SIZE))
123 return -EPERM;
124 flush_icache_range(ip, ip + MCOUNT_INSN_SIZE);
125
126 return 0;
127}
128
129static int ftrace_make_nop_check(struct dyn_ftrace *rec, unsigned long addr)
130{
131 unsigned char __attribute__((aligned(8))) replaced[MCOUNT_INSN_SIZE];
132 unsigned long ip = rec->ip;
133
134 if (probe_kernel_read(replaced, (void *)ip, MCOUNT_INSN_SIZE))
135 return -EFAULT;
136 if (rec->flags & FTRACE_FL_CONVERTED) {
137 struct ftrace_call_insn *call_insn, *tmp_call;
138
139 call_insn = (void *)ftrace_call_code;
140 tmp_call = (void *)replaced;
141 call_insn->imm39_l = tmp_call->imm39_l;
142 call_insn->imm39_h = tmp_call->imm39_h;
143 call_insn->imm20 = tmp_call->imm20;
144 call_insn->i = tmp_call->i;
145 if (memcmp(replaced, ftrace_call_code, MCOUNT_INSN_SIZE) != 0)
146 return -EINVAL;
147 return 0;
148 } else {
149 struct ftrace_orig_insn *call_insn, *tmp_call;
150
151 call_insn = (void *)ftrace_orig_code;
152 tmp_call = (void *)replaced;
153 call_insn->sign = tmp_call->sign;
154 call_insn->imm20 = tmp_call->imm20;
155 if (memcmp(replaced, ftrace_orig_code, MCOUNT_INSN_SIZE) != 0)
156 return -EINVAL;
157 return 0;
158 }
159}
160
161int ftrace_make_nop(struct module *mod,
162 struct dyn_ftrace *rec, unsigned long addr)
163{
164 int ret;
165 char *new;
166
167 ret = ftrace_make_nop_check(rec, addr);
168 if (ret)
169 return ret;
170 new = ftrace_nop_replace();
171 return ftrace_modify_code(rec->ip, NULL, new, 0);
172}
173
174int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
175{
176 unsigned long ip = rec->ip;
177 unsigned char *old, *new;
178
179 old= ftrace_nop_replace();
180 new = ftrace_call_replace(ip, addr);
181 return ftrace_modify_code(ip, old, new, 1);
182}
183
184/* in IA64, _mcount can't directly call ftrace_stub. Only jump is ok */
185int ftrace_update_ftrace_func(ftrace_func_t func)
186{
187 unsigned long ip;
188 unsigned long addr = ((struct fnptr *)ftrace_call)->ip;
189
190 if (func == ftrace_stub)
191 return 0;
192 ip = ((struct fnptr *)func)->ip;
193
194 ia64_patch_imm64(addr + 2, ip);
195
196 flush_icache_range(addr, addr + 16);
197 return 0;
198}
199
200/* run from kstop_machine */
201int __init ftrace_dyn_arch_init(void *data)
202{
203 *(unsigned long *)data = 0;
204
205 return 0;
206}