[PATCH] ARM: hw_breakpoint: avoid UNPREDICTABLE behaviour when reading DBGDSCR
From: Will Deacon <hidden>
Date: 2011-02-09 10:34:11
Subsystem:
arm pmu profiling and debugging, arm port, the rest · Maintainers:
Will Deacon, Mark Rutland, Russell King, Linus Torvalds
Reading baseline CP14 registers, other than DBGDIDR, when the OS Lock is set leads to UNPREDICTABLE behaviour. This patch ensures that we clear the OS lock before accessing anything other than the DBGDIDR, thereby avoiding this behaviour. Signed-off-by: Will Deacon <redacted> --- arch/arm/kernel/hw_breakpoint.c | 16 ++++++++-------- 1 files changed, 8 insertions(+), 8 deletions(-)
diff --git a/arch/arm/kernel/hw_breakpoint.c b/arch/arm/kernel/hw_breakpoint.c
index c9f3f04..19bedab 100644
--- a/arch/arm/kernel/hw_breakpoint.c
+++ b/arch/arm/kernel/hw_breakpoint.c@@ -899,18 +899,18 @@ static int __init arch_hw_breakpoint_init(void) pr_info("%d breakpoint(s) reserved for watchpoint " "single-step.\n", core_num_reserved_brps); + /* + * Reset the breakpoint resources. We assume that a halting + * debugger will leave the world in a nice state for us. + */ + on_each_cpu(reset_ctrl_regs, NULL, 1); + ARM_DBG_READ(c1, 0, dscr); if (dscr & ARM_DSCR_HDBGEN) { + max_watchpoint_len = 4; pr_warning("halting debug mode enabled. Assuming maximum " - "watchpoint size of 4 bytes."); + "watchpoint size of %u bytes.", max_watchpoint_len); } else { - /* - * Reset the breakpoint resources. We assume that a halting - * debugger will leave the world in a nice state for us. - */ - smp_call_function(reset_ctrl_regs, NULL, 1); - reset_ctrl_regs(NULL); - /* Work out the maximum supported watchpoint length. */ max_watchpoint_len = get_max_wp_len(); pr_info("maximum watchpoint size is %u bytes.\n",
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1.7.0.4