diff options
| author | Rabin Vincent <rabin.vincent@stericsson.com> | 2011-10-26 16:49:01 +0530 |
|---|---|---|
| committer | Philippe Langlais <philippe.langlais@stericsson.com> | 2012-05-22 11:01:09 +0200 |
| commit | 02e5d5302d571654906c181750d502c9f06d004b (patch) | |
| tree | 81fe2b9cf1af36ce18673e2846b738d56957d22f /arch | |
| parent | 13a169d8f53948b0cddc0b27cd0f21b682897873 (diff) | |
ARM: hw_breakpoint: don't fault when debug is not powered
If the debug logic is not powered, the processor can unfortunately
raise an undefined instruction exception on the instruction that
we use to check if the debug logic is powered up or not.
Handle this with an undef hook, so that the kernel doesn't crash
on boot on such setups.
ST-Ericsson ID: 370131
ST-Ericsson Linux next: NA
ST-Ericsson FOSS-OUT ID: Trivial
Change-Id: I5802811ac0676d3d13782897b6941dcaee3e4721
Signed-off-by: Rabin Vincent <rabin.vincent@stericsson.com>
Reviewed-on: http://gerrit.lud.stericsson.com/gerrit/35326
Reviewed-by: QABUILD
Reviewed-by: Jonas ABERG <jonas.aberg@stericsson.com>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/arm/kernel/hw_breakpoint.c | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/arch/arm/kernel/hw_breakpoint.c b/arch/arm/kernel/hw_breakpoint.c index ba386bd9410..180dd9f5b19 100644 --- a/arch/arm/kernel/hw_breakpoint.c +++ b/arch/arm/kernel/hw_breakpoint.c @@ -853,6 +853,25 @@ static int hw_breakpoint_pending(unsigned long addr, unsigned int fsr, return ret; } +static int hw_breakpoint_undef(struct pt_regs *regs, unsigned int instr) +{ + int reg = (instr >> 12) & 15; + + /* Fake sticky power-down cleared */ + regs->uregs[reg] = 0; + regs->ARM_pc += 4; + + return 0; +} + +static struct undef_hook hw_breakpoint_hook = { + .instr_mask = 0xffff0fff, + .instr_val = 0xee110e95, + .cpsr_mask = MODE_MASK, + .cpsr_val = SVC_MODE, + .fn = hw_breakpoint_undef, +}; + /* * One-time initialisation. */ @@ -899,6 +918,10 @@ static void reset_ctrl_regs(void *unused) /* * Ensure sticky power-down is clear (i.e. debug logic is * powered up). + * + * This could raise an undefined instruction exception. If it + * does, it is fixed up with an undef hook which constructs + * a fake value with the sticky power-down bit cleared. */ asm volatile("mrc p14, 0, %0, c1, c5, 4" : "=r" (dbg_power)); if ((dbg_power & 0x1) == 0) @@ -986,6 +1009,8 @@ static int __init arch_hw_breakpoint_init(void) */ register_undef_hook(&debug_reg_hook); + register_undef_hook(&hw_breakpoint_hook); + /* * Reset the breakpoint resources. We assume that a halting * debugger will leave the world in a nice state for us. |