From ed19b739c5c76ad241d30f6c6a5ee96fb284f4cf Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Fri, 11 Feb 2011 15:55:12 +0100 Subject: ARM: 6656/1: hw_breakpoint: avoid UNPREDICTABLE behaviour when reading DBGDSCR 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 Signed-off-by: Russell King --- arch/arm/kernel/hw_breakpoint.c | 26 +++++++++++++------------- 1 file changed, 13 insertions(+), 13 deletions(-) (limited to 'arch/arm/kernel/hw_breakpoint.c') diff --git a/arch/arm/kernel/hw_breakpoint.c b/arch/arm/kernel/hw_breakpoint.c index c9f3f046757..ab02d8aadb7 100644 --- a/arch/arm/kernel/hw_breakpoint.c +++ b/arch/arm/kernel/hw_breakpoint.c @@ -834,11 +834,11 @@ static void reset_ctrl_regs(void *unused) /* * v7 debug contains save and restore registers so that debug state - * can be maintained across low-power modes without leaving - * the debug logic powered up. It is IMPLEMENTATION DEFINED whether - * we can write to the debug registers out of reset, so we must - * unlock the OS Lock Access Register to avoid taking undefined - * instruction exceptions later on. + * can be maintained across low-power modes without leaving the debug + * logic powered up. It is IMPLEMENTATION DEFINED whether we can access + * the debug registers out of reset, so we must unlock the OS Lock + * Access Register to avoid taking undefined instruction exceptions + * later on. */ if (debug_arch >= ARM_DEBUG_ARCH_V7_ECP14) { /* @@ -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", -- cgit v1.2.3-70-g09d2 From 66e1cfe6d52c69d317e9df76ebc8538a34af0d51 Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Fri, 11 Feb 2011 16:01:42 +0100 Subject: ARM: 6657/1: hw_breakpoint: fix ptrace breakpoint advertising on unsupported arch The ptrace debug information register was advertising breakpoint and watchpoint resources for unsupported debug architectures. This meant that setting breakpoints on these architectures would appear to succeed, although they would never fire in reality. This patch fixes the breakpoint slot probing so that it returns 0 when running on an unsupported debug architecture. Reported-by: Ulrich Weigand Signed-off-by: Will Deacon Signed-off-by: Russell King --- arch/arm/kernel/hw_breakpoint.c | 18 +++++++++++++----- 1 file changed, 13 insertions(+), 5 deletions(-) (limited to 'arch/arm/kernel/hw_breakpoint.c') diff --git a/arch/arm/kernel/hw_breakpoint.c b/arch/arm/kernel/hw_breakpoint.c index ab02d8aadb7..d600bd35070 100644 --- a/arch/arm/kernel/hw_breakpoint.c +++ b/arch/arm/kernel/hw_breakpoint.c @@ -137,11 +137,10 @@ static u8 get_debug_arch(void) u32 didr; /* Do we implement the extended CPUID interface? */ - if (((read_cpuid_id() >> 16) & 0xf) != 0xf) { - pr_warning("CPUID feature registers not supported. " - "Assuming v6 debug is present.\n"); + if (WARN_ONCE((((read_cpuid_id() >> 16) & 0xf) != 0xf), + "CPUID feature registers not supported. " + "Assuming v6 debug is present.\n")) return ARM_DEBUG_ARCH_V6; - } ARM_DBG_READ(c0, 0, didr); return (didr >> 16) & 0xf; @@ -152,6 +151,12 @@ u8 arch_get_debug_arch(void) return debug_arch; } +static int debug_arch_supported(void) +{ + u8 arch = get_debug_arch(); + return arch >= ARM_DEBUG_ARCH_V6 && arch <= ARM_DEBUG_ARCH_V7_ECP14; +} + /* Determine number of BRP register available. */ static int get_num_brp_resources(void) { @@ -268,6 +273,9 @@ out: int hw_breakpoint_slots(int type) { + if (!debug_arch_supported()) + return 0; + /* * We can be called early, so don't rely on * our static variables being initialised. @@ -882,7 +890,7 @@ static int __init arch_hw_breakpoint_init(void) debug_arch = get_debug_arch(); - if (debug_arch > ARM_DEBUG_ARCH_V7_ECP14) { + if (!debug_arch_supported()) { pr_info("debug architecture 0x%x unsupported.\n", debug_arch); return 0; } -- cgit v1.2.3-70-g09d2