MIPS: traps: Set correct address limit for breakpoints and traps
When a breakpoint or trap happens when operating in kernel mode but on users behalf (eg syscall) it is necessary to change the address limit to KERNEL_DS so any address checking can be bypassed and print the correct stack trace. Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com> Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
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@ -865,6 +865,11 @@ asmlinkage void do_bp(struct pt_regs *regs)
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enum ctx_state prev_state;
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unsigned long epc;
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u16 instr[2];
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mm_segment_t seg;
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seg = get_fs();
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if (!user_mode(regs))
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set_fs(KERNEL_DS);
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prev_state = exception_enter();
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if (get_isa16_mode(regs->cp0_epc)) {
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@ -924,6 +929,7 @@ asmlinkage void do_bp(struct pt_regs *regs)
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do_trap_or_bp(regs, bcode, "Break");
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out:
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set_fs(seg);
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exception_exit(prev_state);
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return;
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@ -937,8 +943,13 @@ asmlinkage void do_tr(struct pt_regs *regs)
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u32 opcode, tcode = 0;
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enum ctx_state prev_state;
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u16 instr[2];
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mm_segment_t seg;
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unsigned long epc = msk_isa16_mode(exception_epc(regs));
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seg = get_fs();
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if (!user_mode(regs))
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set_fs(get_ds());
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prev_state = exception_enter();
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if (get_isa16_mode(regs->cp0_epc)) {
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if (__get_user(instr[0], (u16 __user *)(epc + 0)) ||
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@ -959,6 +970,7 @@ asmlinkage void do_tr(struct pt_regs *regs)
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do_trap_or_bp(regs, tcode, "Trap");
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out:
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set_fs(seg);
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exception_exit(prev_state);
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return;
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