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DTRACE_KINST(4) 	     Kernel Interfaces Manual		 DTRACE_KINST(4)

NAME
     dtrace_kinst  --  a DTrace provider for tracing arbitrary instructions in a
     given kernel function

SYNOPSIS
     kinst::<function>:<instruction>

DESCRIPTION
     The DTrace kinst provider allows the user to trace  any  instruction  in  a
     given  kernel  function.	<function>  corresponds  to  the  function to be
     traced, and <instruction> is the offset to the  specific  instruction,  and
     can  be  obtained	from  the function's disassembly using kgdb from the gdb
     package.

     kinst creates probes on-demand, meaning it  searches  for	and  parses  the
     function's  instructions each time dtrace(1) is run, and not at module load
     time.  This is in contrast  to  dtrace_fbt(4)'s  load-time  parsing,  since
     kinst  can  potentially  create thousands of probes for just a single func-
     tion, instead of up to two (entry and return) in the case of dtrace_fbt(4).
     A result of this is that dtrace -l -P kinst will not match any probes.

IMPLEMENTATION NOTES
     The provider is currently implemented only for amd64.

EXAMPLES
     Find the offset corresponding to the third instruction  in  vm_fault()  and
     trace it, printing the contents of the RSI register:

	   # kgdb
	   (kgdb) disas /r vm_fault
	   Dump of assembler code for function vm_fault:
	      0xffffffff80876df0 <+0>:	   55	   push   %rbp
	      0xffffffff80876df1 <+1>:	   48 89 e5	   mov	  %rsp,%rbp
	      0xffffffff80876df4 <+4>:	   41 57   push   %r15

	   # dtrace -n 'kinst::vm_fault:4 {printf("%#x", regs[R_RSI]);}'
	     2	81500			    vm_fault:4 0x827c56000
	     2	81500			    vm_fault:4 0x827878000
	     2	81500			    vm_fault:4 0x1fab9bef0000
	     2	81500			    vm_fault:4 0xe16cf749000
	     0	81500			    vm_fault:4 0x13587c366000
	     ...

     Trace all instructions in amd64_syscall():

	   # dtrace -n 'kinst::amd64_syscall:'

SEE ALSO
     dtrace(1), dtrace_fbt(4)

HISTORY
     The kinst provider first appeared in FreeBSD 14.0.

AUTHORS
     This manual page was written by Christos Margiolis <christos@FreeBSD.org>.

FreeBSD ports 15.quarterly	  July 16, 2025 		 DTRACE_KINST(4)

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