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- /*
- * Dynamic function tracing support.
- *
- * Copyright (C) 2008 Shaohua Li <shaohua.li@intel.com>
- *
- * For licencing details, see COPYING.
- *
- * Defines low-level handling of mcount calls when the kernel
- * is compiled with the -pg flag. When using dynamic ftrace, the
- * mcount call-sites get patched lazily with NOP till they are
- * enabled. All code mutation routines here take effect atomically.
- */
- #include <linux/uaccess.h>
- #include <linux/ftrace.h>
- #include <asm/cacheflush.h>
- #include <asm/patch.h>
- /* In IA64, each function will be added below two bundles with -pg option */
- static unsigned char __attribute__((aligned(8)))
- ftrace_orig_code[MCOUNT_INSN_SIZE] = {
- 0x02, 0x40, 0x31, 0x10, 0x80, 0x05, /* alloc r40=ar.pfs,12,8,0 */
- 0xb0, 0x02, 0x00, 0x00, 0x42, 0x40, /* mov r43=r0;; */
- 0x05, 0x00, 0xc4, 0x00, /* mov r42=b0 */
- 0x11, 0x48, 0x01, 0x02, 0x00, 0x21, /* mov r41=r1 */
- 0x00, 0x00, 0x00, 0x02, 0x00, 0x00, /* nop.i 0x0 */
- 0x08, 0x00, 0x00, 0x50 /* br.call.sptk.many b0 = _mcount;; */
- };
- struct ftrace_orig_insn {
- u64 dummy1, dummy2, dummy3;
- u64 dummy4:64-41+13;
- u64 imm20:20;
- u64 dummy5:3;
- u64 sign:1;
- u64 dummy6:4;
- };
- /* mcount stub will be converted below for nop */
- static unsigned char ftrace_nop_code[MCOUNT_INSN_SIZE] = {
- 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, /* [MII] nop.m 0x0 */
- 0x30, 0x00, 0x00, 0x60, 0x00, 0x00, /* mov r3=ip */
- 0x00, 0x00, 0x04, 0x00, /* nop.i 0x0 */
- 0x05, 0x00, 0x00, 0x00, 0x01, 0x00, /* [MLX] nop.m 0x0 */
- 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* nop.x 0x0;; */
- 0x00, 0x00, 0x04, 0x00
- };
- static unsigned char *ftrace_nop_replace(void)
- {
- return ftrace_nop_code;
- }
- /*
- * mcount stub will be converted below for call
- * Note: Just the last instruction is changed against nop
- * */
- static unsigned char __attribute__((aligned(8)))
- ftrace_call_code[MCOUNT_INSN_SIZE] = {
- 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, /* [MII] nop.m 0x0 */
- 0x30, 0x00, 0x00, 0x60, 0x00, 0x00, /* mov r3=ip */
- 0x00, 0x00, 0x04, 0x00, /* nop.i 0x0 */
- 0x05, 0x00, 0x00, 0x00, 0x01, 0x00, /* [MLX] nop.m 0x0 */
- 0xff, 0xff, 0xff, 0xff, 0x7f, 0x00, /* brl.many .;;*/
- 0xf8, 0xff, 0xff, 0xc8
- };
- struct ftrace_call_insn {
- u64 dummy1, dummy2;
- u64 dummy3:48;
- u64 imm39_l:16;
- u64 imm39_h:23;
- u64 dummy4:13;
- u64 imm20:20;
- u64 dummy5:3;
- u64 i:1;
- u64 dummy6:4;
- };
- static unsigned char *ftrace_call_replace(unsigned long ip, unsigned long addr)
- {
- struct ftrace_call_insn *code = (void *)ftrace_call_code;
- unsigned long offset = addr - (ip + 0x10);
- code->imm39_l = offset >> 24;
- code->imm39_h = offset >> 40;
- code->imm20 = offset >> 4;
- code->i = offset >> 63;
- return ftrace_call_code;
- }
- static int
- ftrace_modify_code(unsigned long ip, unsigned char *old_code,
- unsigned char *new_code, int do_check)
- {
- unsigned char replaced[MCOUNT_INSN_SIZE];
- /*
- * Note: Due to modules and __init, 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.
- *
- * No real locking needed, this code is run through
- * kstop_machine, or before SMP starts.
- */
- if (!do_check)
- goto skip_check;
- /* read the text we want to modify */
- if (probe_kernel_read(replaced, (void *)ip, MCOUNT_INSN_SIZE))
- return -EFAULT;
- /* Make sure it is what we expect it to be */
- if (memcmp(replaced, old_code, MCOUNT_INSN_SIZE) != 0)
- return -EINVAL;
- skip_check:
- /* replace the text with the new text */
- if (probe_kernel_write(((void *)ip), new_code, MCOUNT_INSN_SIZE))
- return -EPERM;
- flush_icache_range(ip, ip + MCOUNT_INSN_SIZE);
- return 0;
- }
- static int ftrace_make_nop_check(struct dyn_ftrace *rec, unsigned long addr)
- {
- unsigned char __attribute__((aligned(8))) replaced[MCOUNT_INSN_SIZE];
- unsigned long ip = rec->ip;
- if (probe_kernel_read(replaced, (void *)ip, MCOUNT_INSN_SIZE))
- return -EFAULT;
- if (rec->flags & FTRACE_FL_CONVERTED) {
- struct ftrace_call_insn *call_insn, *tmp_call;
- call_insn = (void *)ftrace_call_code;
- tmp_call = (void *)replaced;
- call_insn->imm39_l = tmp_call->imm39_l;
- call_insn->imm39_h = tmp_call->imm39_h;
- call_insn->imm20 = tmp_call->imm20;
- call_insn->i = tmp_call->i;
- if (memcmp(replaced, ftrace_call_code, MCOUNT_INSN_SIZE) != 0)
- return -EINVAL;
- return 0;
- } else {
- struct ftrace_orig_insn *call_insn, *tmp_call;
- call_insn = (void *)ftrace_orig_code;
- tmp_call = (void *)replaced;
- call_insn->sign = tmp_call->sign;
- call_insn->imm20 = tmp_call->imm20;
- if (memcmp(replaced, ftrace_orig_code, MCOUNT_INSN_SIZE) != 0)
- return -EINVAL;
- return 0;
- }
- }
- int ftrace_make_nop(struct module *mod,
- struct dyn_ftrace *rec, unsigned long addr)
- {
- int ret;
- char *new;
- ret = ftrace_make_nop_check(rec, addr);
- if (ret)
- return ret;
- new = ftrace_nop_replace();
- return ftrace_modify_code(rec->ip, NULL, new, 0);
- }
- int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
- {
- unsigned long ip = rec->ip;
- unsigned char *old, *new;
- old= ftrace_nop_replace();
- new = ftrace_call_replace(ip, addr);
- return ftrace_modify_code(ip, old, new, 1);
- }
- /* in IA64, _mcount can't directly call ftrace_stub. Only jump is ok */
- int ftrace_update_ftrace_func(ftrace_func_t func)
- {
- unsigned long ip;
- unsigned long addr = ((struct fnptr *)ftrace_call)->ip;
- if (func == ftrace_stub)
- return 0;
- ip = ((struct fnptr *)func)->ip;
- ia64_patch_imm64(addr + 2, ip);
- flush_icache_range(addr, addr + 16);
- return 0;
- }
- /* run from kstop_machine */
- int __init ftrace_dyn_arch_init(void)
- {
- return 0;
- }
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