133 lines
2.7 KiB
C
133 lines
2.7 KiB
C
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/*
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* Dynamic function tracer architecture backend.
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*
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* Copyright IBM Corp. 2009
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*
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* Author(s): Heiko Carstens <heiko.carstens@de.ibm.com>,
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*
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*/
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#include <linux/uaccess.h>
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#include <linux/ftrace.h>
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#include <linux/kernel.h>
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#include <linux/types.h>
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#include <asm/lowcore.h>
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void ftrace_disable_code(void);
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void ftrace_call_code(void);
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void ftrace_nop_code(void);
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#define FTRACE_INSN_SIZE 4
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#ifdef CONFIG_64BIT
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asm(
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" .align 4\n"
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"ftrace_disable_code:\n"
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" j 0f\n"
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" .word 0x0024\n"
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" lg %r1,"__stringify(__LC_FTRACE_FUNC)"\n"
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" basr %r14,%r1\n"
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" lg %r14,8(15)\n"
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" lgr %r0,%r0\n"
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"0:\n");
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asm(
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" .align 4\n"
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"ftrace_nop_code:\n"
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" j .+"__stringify(MCOUNT_INSN_SIZE)"\n");
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asm(
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" .align 4\n"
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"ftrace_call_code:\n"
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" stg %r14,8(%r15)\n");
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#else /* CONFIG_64BIT */
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asm(
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" .align 4\n"
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"ftrace_disable_code:\n"
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" j 0f\n"
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" l %r1,"__stringify(__LC_FTRACE_FUNC)"\n"
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" basr %r14,%r1\n"
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" l %r14,4(%r15)\n"
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" j 0f\n"
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" bcr 0,%r7\n"
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" bcr 0,%r7\n"
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" bcr 0,%r7\n"
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" bcr 0,%r7\n"
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" bcr 0,%r7\n"
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" bcr 0,%r7\n"
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"0:\n");
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asm(
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" .align 4\n"
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"ftrace_nop_code:\n"
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" j .+"__stringify(MCOUNT_INSN_SIZE)"\n");
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asm(
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" .align 4\n"
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"ftrace_call_code:\n"
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" st %r14,4(%r15)\n");
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#endif /* CONFIG_64BIT */
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static int ftrace_modify_code(unsigned long ip,
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void *old_code, int old_size,
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void *new_code, int new_size)
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{
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unsigned char replaced[MCOUNT_INSN_SIZE];
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/*
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* Note: Due to modules code can disappear and change.
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* We need to protect against faulting as well as code
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* changing. We do this by using the probe_kernel_*
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* functions.
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* This however is just a simple sanity check.
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*/
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if (probe_kernel_read(replaced, (void *)ip, old_size))
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return -EFAULT;
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if (memcmp(replaced, old_code, old_size) != 0)
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return -EINVAL;
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if (probe_kernel_write((void *)ip, new_code, new_size))
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return -EPERM;
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return 0;
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}
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static int ftrace_make_initial_nop(struct module *mod, struct dyn_ftrace *rec,
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unsigned long addr)
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{
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return ftrace_modify_code(rec->ip,
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ftrace_call_code, FTRACE_INSN_SIZE,
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ftrace_disable_code, MCOUNT_INSN_SIZE);
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}
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int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec,
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unsigned long addr)
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{
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if (addr == MCOUNT_ADDR)
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return ftrace_make_initial_nop(mod, rec, addr);
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return ftrace_modify_code(rec->ip,
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ftrace_call_code, FTRACE_INSN_SIZE,
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ftrace_nop_code, FTRACE_INSN_SIZE);
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}
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int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
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{
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return ftrace_modify_code(rec->ip,
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ftrace_nop_code, FTRACE_INSN_SIZE,
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ftrace_call_code, FTRACE_INSN_SIZE);
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}
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int ftrace_update_ftrace_func(ftrace_func_t func)
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{
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ftrace_dyn_func = (unsigned long)func;
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return 0;
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}
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int __init ftrace_dyn_arch_init(void *data)
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{
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*(unsigned long *)data = 0;
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return 0;
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}
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