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/*
 * Copyright (C) 2000 Anton Blanchard (anton@linuxcare.com)
 *
 * This file implements mcount(), which is used to collect profiling data.
 * This can also be tweaked for kernel stack overflow detection.
 */

#include <linux/config.h>
#include <linux/linkage.h>

#include <asm/asm_offsets.h>
#include <asm/ptrace.h>

/*
 * This is the main variant and is called by C code.  GCC's -pg option
 * automatically instruments every C function with a call to this.
 */

#ifdef CONFIG_STACK_DEBUG

#define OVSTACKSIZE     4096            /* lets hope this is enough */

        .data
        .align          8
panicstring:
        .asciz          "Stack overflow\n"
        .align          8
ovstack:
        .skip           OVSTACKSIZE
#endif
        .text
        .align 32
        .globl mcount
mcount:
#ifdef CONFIG_STACK_DEBUG
        /*
         * Check whether %sp is dangerously low.
         */
        ldub            [%g6 + AOFF_task_thread + AOFF_thread_fpdepth], %g1
        srl             %g1, 1, %g5
        add             %g5, 1, %g5
        sllx            %g5, 8, %g5                     ! each fpregs frame is 256b
        add             %g5, 192, %g5
        add             %g6, %g5, %g5                   ! where does task_struct+frame end?
        sub             %g5, STACK_BIAS, %g5
        cmp             %sp, %g5
        bg,pt           %xcc, 1f
         sethi          %hi(panicstring), %g5
        sethi           %hi(ovstack), %g7               ! cant move to panic stack fast enough
         or             %g7, %lo(ovstack), %g7
        add             %g7, OVSTACKSIZE, %g7
        sub             %g7, STACK_BIAS, %g7
        mov             %g7, %sp
        call            prom_printf
         or             %g5, %lo(panicstring), %o0
        call            prom_halt
         nop
#endif
1:      retl
         nop