77 lines
1.6 KiB
C
77 lines
1.6 KiB
C
#include <linux/spinlock.h>
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#include <linux/hardirq.h>
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#include <linux/ftrace.h>
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#include <linux/percpu.h>
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#include <linux/init.h>
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#include <linux/list.h>
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#include <asm/ftrace.h>
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static const u32 ftrace_nop = 0x01000000;
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unsigned char *ftrace_nop_replace(void)
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{
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return (char *)&ftrace_nop;
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}
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unsigned char *ftrace_call_replace(unsigned long ip, unsigned long addr)
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{
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static u32 call;
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s32 off;
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off = ((s32)addr - (s32)ip);
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call = 0x40000000 | ((u32)off >> 2);
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return (unsigned char *) &call;
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}
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int
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ftrace_modify_code(unsigned long ip, unsigned char *old_code,
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unsigned char *new_code)
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{
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u32 old = *(u32 *)old_code;
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u32 new = *(u32 *)new_code;
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u32 replaced;
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int faulted;
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__asm__ __volatile__(
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"1: cas [%[ip]], %[old], %[new]\n"
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" flush %[ip]\n"
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" mov 0, %[faulted]\n"
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"2:\n"
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" .section .fixup,#alloc,#execinstr\n"
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" .align 4\n"
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"3: sethi %%hi(2b), %[faulted]\n"
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" jmpl %[faulted] + %%lo(2b), %%g0\n"
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" mov 1, %[faulted]\n"
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" .previous\n"
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" .section __ex_table,\"a\"\n"
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" .align 4\n"
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" .word 1b, 3b\n"
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" .previous\n"
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: "=r" (replaced), [faulted] "=r" (faulted)
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: [new] "0" (new), [old] "r" (old), [ip] "r" (ip)
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: "memory");
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if (replaced != old && replaced != new)
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faulted = 2;
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return faulted;
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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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unsigned long ip = (unsigned long)(&ftrace_call);
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unsigned char old[MCOUNT_INSN_SIZE], *new;
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memcpy(old, &ftrace_call, MCOUNT_INSN_SIZE);
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new = ftrace_call_replace(ip, (unsigned long)func);
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return ftrace_modify_code(ip, old, new);
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}
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int __init ftrace_dyn_arch_init(void *data)
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{
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ftrace_mcount_set(data);
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return 0;
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}
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