From f5206faf707ec754f4eccf789e9c9c9156308a15 Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Fri, 21 Sep 2012 15:08:17 +0100 Subject: [PATCH] ARM: hw_breakpoint: fix monitor mode detection with v7.1 Detecting whether halting debug is enabled is no longer possible via the DBGDSCR in v7.1, returning an UNKNOWN value for the HDBGen bit via CP14 when the OS lock is clear. This patch removes the halting mode check and ensures that accesses to the internal and external views of the DBGDSCR are serialised with an instruction barrier. Signed-off-by: Will Deacon --- arch/arm/kernel/hw_breakpoint.c | 25 +++++-------------------- 1 file changed, 5 insertions(+), 20 deletions(-) diff --git a/arch/arm/kernel/hw_breakpoint.c b/arch/arm/kernel/hw_breakpoint.c index ec16adac9af7..169dcce83d13 100644 --- a/arch/arm/kernel/hw_breakpoint.c +++ b/arch/arm/kernel/hw_breakpoint.c @@ -235,13 +235,6 @@ static int enable_monitor_mode(void) ARM_DBG_READ(c1, 0, dscr); - /* Ensure that halting mode is disabled. */ - if (WARN_ONCE(dscr & ARM_DSCR_HDBGEN, - "halting debug mode enabled. Unable to access hardware resources.\n")) { - ret = -EPERM; - goto out; - } - /* If monitor mode is already enabled, just return. */ if (dscr & ARM_DSCR_MDBGEN) goto out; @@ -255,6 +248,7 @@ static int enable_monitor_mode(void) case ARM_DEBUG_ARCH_V7_ECP14: case ARM_DEBUG_ARCH_V7_1: ARM_DBG_WRITE(c2, 2, (dscr | ARM_DSCR_MDBGEN)); + isb(); break; default: ret = -ENODEV; @@ -1000,8 +994,6 @@ static struct notifier_block __cpuinitdata dbg_reset_nb = { static int __init arch_hw_breakpoint_init(void) { - u32 dscr; - debug_arch = get_debug_arch(); if (!debug_arch_supported()) { @@ -1036,17 +1028,10 @@ static int __init arch_hw_breakpoint_init(void) core_num_brps, core_has_mismatch_brps() ? "(+1 reserved) " : "", core_num_wrps); - 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 %u bytes.\n", - max_watchpoint_len); - } else { - /* Work out the maximum supported watchpoint length. */ - max_watchpoint_len = get_max_wp_len(); - pr_info("maximum watchpoint size is %u bytes.\n", - max_watchpoint_len); - } + /* Work out the maximum supported watchpoint length. */ + max_watchpoint_len = get_max_wp_len(); + pr_info("maximum watchpoint size is %u bytes.\n", + max_watchpoint_len); /* Register debug fault handler. */ hook_fault_code(FAULT_CODE_DEBUG, hw_breakpoint_pending, SIGTRAP, -- 2.39.5