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kgdb.c

/* kgdb.c: KGDB support for 64-bit sparc.
 *
 * Copyright (C) 2008 David S. Miller <davem@davemloft.net>
 */

#include <linux/kgdb.h>
#include <linux/kdebug.h>

#include <asm/kdebug.h>
#include <asm/ptrace.h>
#include <asm/irq.h>

void pt_regs_to_gdb_regs(unsigned long *gdb_regs, struct pt_regs *regs)
{
      struct reg_window *win;
      int i;

      gdb_regs[GDB_G0] = 0;
      for (i = 0; i < 15; i++)
            gdb_regs[GDB_G1 + i] = regs->u_regs[UREG_G1 + i];

      win = (struct reg_window *) (regs->u_regs[UREG_FP] + STACK_BIAS);
      for (i = 0; i < 8; i++)
            gdb_regs[GDB_L0 + i] = win->locals[i];
      for (i = 0; i < 8; i++)
            gdb_regs[GDB_I0 + i] = win->ins[i];

      for (i = GDB_F0; i <= GDB_F62; i++)
            gdb_regs[i] = 0;

      gdb_regs[GDB_PC] = regs->tpc;
      gdb_regs[GDB_NPC] = regs->tnpc;
      gdb_regs[GDB_STATE] = regs->tstate;
      gdb_regs[GDB_FSR] = 0;
      gdb_regs[GDB_FPRS] = 0;
      gdb_regs[GDB_Y] = regs->y;
}

void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *p)
{
      struct thread_info *t = task_thread_info(p);
      extern unsigned int switch_to_pc;
      extern unsigned int ret_from_syscall;
      struct reg_window *win;
      unsigned long pc, cwp;
      int i;

      for (i = GDB_G0; i < GDB_G6; i++)
            gdb_regs[i] = 0;
      gdb_regs[GDB_G6] = (unsigned long) t;
      gdb_regs[GDB_G7] = (unsigned long) p;
      for (i = GDB_O0; i < GDB_SP; i++)
            gdb_regs[i] = 0;
      gdb_regs[GDB_SP] = t->ksp;
      gdb_regs[GDB_O7] = 0;

      win = (struct reg_window *) (t->ksp + STACK_BIAS);
      for (i = 0; i < 8; i++)
            gdb_regs[GDB_L0 + i] = win->locals[i];
      for (i = 0; i < 8; i++)
            gdb_regs[GDB_I0 + i] = win->ins[i];

      for (i = GDB_F0; i <= GDB_F62; i++)
            gdb_regs[i] = 0;

      if (t->new_child)
            pc = (unsigned long) &ret_from_syscall;
      else
            pc = (unsigned long) &switch_to_pc;

      gdb_regs[GDB_PC] = pc;
      gdb_regs[GDB_NPC] = pc + 4;

      cwp = __thread_flag_byte_ptr(t)[TI_FLAG_BYTE_CWP];

      gdb_regs[GDB_STATE] = (TSTATE_PRIV | TSTATE_IE | cwp);
      gdb_regs[GDB_FSR] = 0;
      gdb_regs[GDB_FPRS] = 0;
      gdb_regs[GDB_Y] = 0;
}

void gdb_regs_to_pt_regs(unsigned long *gdb_regs, struct pt_regs *regs)
{
      struct reg_window *win;
      int i;

      for (i = 0; i < 15; i++)
            regs->u_regs[UREG_G1 + i] = gdb_regs[GDB_G1 + i];

      /* If the TSTATE register is changing, we have to preserve
       * the CWP field, otherwise window save/restore explodes.
       */
      if (regs->tstate != gdb_regs[GDB_STATE]) {
            unsigned long cwp = regs->tstate & TSTATE_CWP;

            regs->tstate = (gdb_regs[GDB_STATE] & ~TSTATE_CWP) | cwp;
      }

      regs->tpc = gdb_regs[GDB_PC];
      regs->tnpc = gdb_regs[GDB_NPC];
      regs->y = gdb_regs[GDB_Y];

      win = (struct reg_window *) (regs->u_regs[UREG_FP] + STACK_BIAS);
      for (i = 0; i < 8; i++)
            win->locals[i] = gdb_regs[GDB_L0 + i];
      for (i = 0; i < 8; i++)
            win->ins[i] = gdb_regs[GDB_I0 + i];
}

#ifdef CONFIG_SMP
void smp_kgdb_capture_client(struct pt_regs *regs)
{
      unsigned long flags;

      __asm__ __volatile__("rdpr      %%pstate, %0\n\t"
                       "wrpr      %0, %1, %%pstate"
                       : "=r" (flags)
                       : "i" (PSTATE_IE));

      flushw_all();

      if (atomic_read(&kgdb_active) != -1)
            kgdb_nmicallback(raw_smp_processor_id(), regs);

      __asm__ __volatile__("wrpr    %0, 0, %%pstate"
                       : : "r" (flags));
}
#endif

int kgdb_arch_handle_exception(int e_vector, int signo, int err_code,
                         char *remcomInBuffer, char *remcomOutBuffer,
                         struct pt_regs *linux_regs)
{
      unsigned long addr;
      char *ptr;

      switch (remcomInBuffer[0]) {
      case 'c':
            /* try to read optional parameter, pc unchanged if no parm */
            ptr = &remcomInBuffer[1];
            if (kgdb_hex2long(&ptr, &addr)) {
                  linux_regs->tpc = addr;
                  linux_regs->tnpc = addr + 4;
            }
            /* fallthru */

      case 'D':
      case 'k':
            if (linux_regs->tpc == (unsigned long) arch_kgdb_breakpoint) {
                  linux_regs->tpc = linux_regs->tnpc;
                  linux_regs->tnpc += 4;
            }
            return 0;
      }
      return -1;
}

asmlinkage void kgdb_trap(unsigned long trap_level, struct pt_regs *regs)
{
      unsigned long flags;

      if (user_mode(regs)) {
            bad_trap(regs, trap_level);
            return;
      }

      flushw_all();

      local_irq_save(flags);
      kgdb_handle_exception(0x172, SIGTRAP, 0, regs);
      local_irq_restore(flags);
}

int kgdb_arch_init(void)
{
      return 0;
}

void kgdb_arch_exit(void)
{
}

struct kgdb_arch arch_kgdb_ops = {
      /* Breakpoint instruction: ta 0x72 */
      .gdb_bpt_instr          = { 0x91, 0xd0, 0x20, 0x72 },
};

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