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MIPS: traps: Set correct address limit for breakpoints and traps

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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>
This commit is contained in:
Leonid Yegoshin
2013-12-04 16:39:34 +00:00
committed by Ralf Baechle
parent b08a9c95f8
commit 078dde5e21
1 changed files with 12 additions and 0 deletions
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12
arch/mips/kernel/traps.c
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@@ -865,6 +865,11 @@ asmlinkage void do_bp(struct pt_regs *regs)
enum ctx_state prev_state; enum ctx_state prev_state;
unsigned long epc; unsigned long epc;
u16 instr[2]; u16 instr[2];
mm_segment_t seg;
seg = get_fs();
if (!user_mode(regs))
set_fs(KERNEL_DS);
prev_state = exception_enter(); prev_state = exception_enter();
if (get_isa16_mode(regs->cp0_epc)) { if (get_isa16_mode(regs->cp0_epc)) {
@@ -924,6 +929,7 @@ asmlinkage void do_bp(struct pt_regs *regs)
do_trap_or_bp(regs, bcode, "Break"); do_trap_or_bp(regs, bcode, "Break");
out: out:
set_fs(seg);
exception_exit(prev_state); exception_exit(prev_state);
return; return;
@@ -937,8 +943,13 @@ asmlinkage void do_tr(struct pt_regs *regs)
u32 opcode, tcode = 0; u32 opcode, tcode = 0;
enum ctx_state prev_state; enum ctx_state prev_state;
u16 instr[2]; u16 instr[2];
mm_segment_t seg;
unsigned long epc = msk_isa16_mode(exception_epc(regs)); unsigned long epc = msk_isa16_mode(exception_epc(regs));
seg = get_fs();
if (!user_mode(regs))
set_fs(get_ds());
prev_state = exception_enter(); prev_state = exception_enter();
if (get_isa16_mode(regs->cp0_epc)) { if (get_isa16_mode(regs->cp0_epc)) {
if (__get_user(instr[0], (u16 __user *)(epc + 0)) || if (__get_user(instr[0], (u16 __user *)(epc + 0)) ||
@@ -959,6 +970,7 @@ asmlinkage void do_tr(struct pt_regs *regs)
do_trap_or_bp(regs, tcode, "Trap"); do_trap_or_bp(regs, tcode, "Trap");
out: out:
set_fs(seg);
exception_exit(prev_state); exception_exit(prev_state);
return; return;