From 404b27d66ed657ebccb08a9c8f8f65523e9b666b Mon Sep 17 00:00:00 2001 From: Michael Neuling Date: Tue, 27 Mar 2018 15:37:17 +1100 Subject: powerpc: Add ppc_breakpoint_available() Add ppc_breakpoint_available() to determine if a breakpoint is available currently via the DAWR or DABR. Signed-off-by: Michael Neuling Signed-off-by: Michael Ellerman --- arch/powerpc/kernel/process.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) (limited to 'arch/powerpc/kernel') diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c index 1738c4127b32..4466e3db46d4 100644 --- a/arch/powerpc/kernel/process.c +++ b/arch/powerpc/kernel/process.c @@ -827,6 +827,18 @@ void set_breakpoint(struct arch_hw_breakpoint *brk) preempt_enable(); } +/* Check if we have DAWR or DABR hardware */ +bool ppc_breakpoint_available(void) +{ + if (cpu_has_feature(CPU_FTR_DAWR)) + return true; /* POWER8 DAWR */ + if (cpu_has_feature(CPU_FTR_ARCH_207S)) + return false; /* POWER9 with DAWR disabled */ + /* DABR: Everything but POWER8 and POWER9 */ + return true; +} +EXPORT_SYMBOL_GPL(ppc_breakpoint_available); + #ifdef CONFIG_PPC64 DEFINE_PER_CPU(struct cpu_usage, cpu_usage_array); #endif -- cgit From 85ce9a5d57bec126d19610d6e77f9e6e4eaea635 Mon Sep 17 00:00:00 2001 From: Michael Neuling Date: Tue, 27 Mar 2018 15:37:18 +1100 Subject: powerpc: Update ptrace to use ppc_breakpoint_available() This updates the ptrace code to use ppc_breakpoint_available(). We now advertise via PPC_PTRACE_GETHWDBGINFO zero breakpoints when the DAWR is missing (ie. POWER9). This results in GDB falling back to software emulation of the breakpoint (which is slow). For the features advertised by PPC_PTRACE_GETHWDBGINFO, we keep advertising DAWR as if we don't GDB assumes 1 breakpoint irrespective of the number of breakpoints advertised. GDB then fails later when trying to set this one breakpoint. Signed-off-by: Michael Neuling Signed-off-by: Michael Ellerman --- arch/powerpc/kernel/hw_breakpoint.c | 3 +++ arch/powerpc/kernel/ptrace.c | 16 ++++++++++++++-- 2 files changed, 17 insertions(+), 2 deletions(-) (limited to 'arch/powerpc/kernel') diff --git a/arch/powerpc/kernel/hw_breakpoint.c b/arch/powerpc/kernel/hw_breakpoint.c index 53b9c1dfd7d9..4c1012b80d3b 100644 --- a/arch/powerpc/kernel/hw_breakpoint.c +++ b/arch/powerpc/kernel/hw_breakpoint.c @@ -33,6 +33,7 @@ #include #include #include +#include #include /* @@ -171,6 +172,8 @@ int arch_validate_hwbkpt_settings(struct perf_event *bp) * HW_BREAKPOINT_ALIGN by rounding off to the lower address, the * 'symbolsize' should satisfy the check below. */ + if (!ppc_breakpoint_available()) + return -ENODEV; length_max = 8; /* DABR */ if (cpu_has_feature(CPU_FTR_DAWR)) { length_max = 512 ; /* 64 doublewords */ diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c index ca72d7391d40..d23cf632edf0 100644 --- a/arch/powerpc/kernel/ptrace.c +++ b/arch/powerpc/kernel/ptrace.c @@ -41,6 +41,7 @@ #include #include #include +#include #define CREATE_TRACE_POINTS #include @@ -2378,6 +2379,7 @@ static int ptrace_set_debugreg(struct task_struct *task, unsigned long addr, struct perf_event_attr attr; #endif /* CONFIG_HAVE_HW_BREAKPOINT */ #ifndef CONFIG_PPC_ADV_DEBUG_REGS + bool set_bp = true; struct arch_hw_breakpoint hw_brk; #endif @@ -2411,9 +2413,10 @@ static int ptrace_set_debugreg(struct task_struct *task, unsigned long addr, hw_brk.address = data & (~HW_BRK_TYPE_DABR); hw_brk.type = (data & HW_BRK_TYPE_DABR) | HW_BRK_TYPE_PRIV_ALL; hw_brk.len = 8; + set_bp = (data) && (hw_brk.type & HW_BRK_TYPE_RDWR); #ifdef CONFIG_HAVE_HW_BREAKPOINT bp = thread->ptrace_bps[0]; - if ((!data) || !(hw_brk.type & HW_BRK_TYPE_RDWR)) { + if (!set_bp) { if (bp) { unregister_hw_breakpoint(bp); thread->ptrace_bps[0] = NULL; @@ -2450,6 +2453,9 @@ static int ptrace_set_debugreg(struct task_struct *task, unsigned long addr, return PTR_ERR(bp); } +#else /* !CONFIG_HAVE_HW_BREAKPOINT */ + if (set_bp && (!ppc_breakpoint_available())) + return -ENODEV; #endif /* CONFIG_HAVE_HW_BREAKPOINT */ task->thread.hw_brk = hw_brk; #else /* CONFIG_PPC_ADV_DEBUG_REGS */ @@ -2904,6 +2910,9 @@ static long ppc_set_hwdebug(struct task_struct *child, if (child->thread.hw_brk.address) return -ENOSPC; + if (!ppc_breakpoint_available()) + return -ENODEV; + child->thread.hw_brk = brk; return 1; @@ -3052,7 +3061,10 @@ long arch_ptrace(struct task_struct *child, long request, #endif #else /* !CONFIG_PPC_ADV_DEBUG_REGS */ dbginfo.num_instruction_bps = 0; - dbginfo.num_data_bps = 1; + if (ppc_breakpoint_available()) + dbginfo.num_data_bps = 1; + else + dbginfo.num_data_bps = 0; dbginfo.num_condition_regs = 0; #ifdef CONFIG_PPC64 dbginfo.data_bp_alignment = 8; -- cgit From 622aa35e8f6a077f034fe4ad053b6a2e9d278414 Mon Sep 17 00:00:00 2001 From: Michael Neuling Date: Tue, 27 Mar 2018 15:37:23 +1100 Subject: powerpc: Disable DAWR on POWER9 via CPU feature quirk This disables the DAWR on all POWER9 CPUs via cpu feature quirk. Using the DAWR on POWER9 can cause xstops, hence we need to disable it. Signed-off-by: Michael Neuling Signed-off-by: Michael Ellerman --- arch/powerpc/kernel/dt_cpu_ftrs.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'arch/powerpc/kernel') diff --git a/arch/powerpc/kernel/dt_cpu_ftrs.c b/arch/powerpc/kernel/dt_cpu_ftrs.c index 0a0c601c6ade..0af2c5dc5162 100644 --- a/arch/powerpc/kernel/dt_cpu_ftrs.c +++ b/arch/powerpc/kernel/dt_cpu_ftrs.c @@ -713,6 +713,9 @@ static __init void cpufeatures_cpu_quirks(void) else if ((version & 0xffffefff) == 0x004e0202) cur_cpu_spec->cpu_features |= CPU_FTR_P9_TM_HV_ASSIST | CPU_FTR_P9_TM_XER_SO_BUG; + + if ((version & 0xffff0000) == 0x004e0000) + cur_cpu_spec->cpu_features &= ~(CPU_FTR_DAWR); } static void __init cpufeatures_setup_finished(void) -- cgit