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29 #define __NO_UNDERSCORES__
34 pushq %rbp // setup mcount's frame
36 pushq %rax // save %eax
37 pushf // save interrupt state
38 cli // disable interrupts
41 // Check that this cpu is ready.
42 // This delays the start of mcounting until a cpu is really prepared.
48 movl %gs:CPU_RUNNING,%eax
53 // Test for recursion as indicated by a per-cpu flag.
54 // Skip if nested, otherwise set the flag and call the C mount().
56 movl %gs:CPU_MCOUNT_OFF,%eax
57 testl %eax,%eax // test for recursion
60 incl %gs:CPU_MCOUNT_OFF // set recursion flag
62 movq (%rbp),%rax // frame pointer of mcount's caller
69 movq 8(%rax),%rdi // mcount's caller's return address
70 movq 8(%rbp),%rsi // push selfpc parameter for mcount()
72 call _mcount // call the C mcount
81 decl %gs:CPU_MCOUNT_OFF // turn off recursion flag
83 popf // restore interrupt state
85 movq %rbp,%rsp // tear down mcount's frame