diff options
Diffstat (limited to 'arch/powerpc/kernel/hw_breakpoint.c')
| -rw-r--r-- | arch/powerpc/kernel/hw_breakpoint.c | 78 |
1 files changed, 62 insertions, 16 deletions
diff --git a/arch/powerpc/kernel/hw_breakpoint.c b/arch/powerpc/kernel/hw_breakpoint.c index fec8a6773119..a293a53b4365 100644 --- a/arch/powerpc/kernel/hw_breakpoint.c +++ b/arch/powerpc/kernel/hw_breakpoint.c @@ -1,25 +1,11 @@ +// SPDX-License-Identifier: GPL-2.0-or-later /* * HW_breakpoint: a unified kernel/user-space hardware breakpoint facility, * using the CPU's debug registers. Derived from * "arch/x86/kernel/hw_breakpoint.c" * - * This program is free software; you can redistribute it and/or modify - * it under the terms of the GNU General Public License as published by - * the Free Software Foundation; either version 2 of the License, or - * (at your option) any later version. - * - * This program is distributed in the hope that it will be useful, - * but WITHOUT ANY WARRANTY; without even the implied warranty of - * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the - * GNU General Public License for more details. - * - * You should have received a copy of the GNU General Public License - * along with this program; if not, write to the Free Software - * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. - * * Copyright 2010 IBM Corporation * Author: K.Prasad <prasad@linux.vnet.ibm.com> - * */ #include <linux/hw_breakpoint.h> @@ -29,11 +15,15 @@ #include <linux/kernel.h> #include <linux/sched.h> #include <linux/smp.h> +#include <linux/debugfs.h> +#include <linux/init.h> #include <asm/hw_breakpoint.h> #include <asm/processor.h> #include <asm/sstep.h> #include <asm/debug.h> +#include <asm/debugfs.h> +#include <asm/hvcall.h> #include <linux/uaccess.h> /* @@ -174,7 +164,7 @@ int hw_breakpoint_arch_parse(struct perf_event *bp, if (!ppc_breakpoint_available()) return -ENODEV; length_max = 8; /* DABR */ - if (cpu_has_feature(CPU_FTR_DAWR)) { + if (dawr_enabled()) { length_max = 512 ; /* 64 doublewords */ /* DAWR region can't cross 512 boundary */ if ((attr->bp_addr >> 9) != @@ -376,3 +366,59 @@ void hw_breakpoint_pmu_read(struct perf_event *bp) { /* TODO */ } + +bool dawr_force_enable; +EXPORT_SYMBOL_GPL(dawr_force_enable); + +static ssize_t dawr_write_file_bool(struct file *file, + const char __user *user_buf, + size_t count, loff_t *ppos) +{ + struct arch_hw_breakpoint null_brk = {0, 0, 0}; + size_t rc; + + /* Send error to user if they hypervisor won't allow us to write DAWR */ + if ((!dawr_force_enable) && + (firmware_has_feature(FW_FEATURE_LPAR)) && + (set_dawr(&null_brk) != H_SUCCESS)) + return -1; + + rc = debugfs_write_file_bool(file, user_buf, count, ppos); + if (rc) + return rc; + + /* If we are clearing, make sure all CPUs have the DAWR cleared */ + if (!dawr_force_enable) + smp_call_function((smp_call_func_t)set_dawr, &null_brk, 0); + + return rc; +} + +static const struct file_operations dawr_enable_fops = { + .read = debugfs_read_file_bool, + .write = dawr_write_file_bool, + .open = simple_open, + .llseek = default_llseek, +}; + +static int __init dawr_force_setup(void) +{ + dawr_force_enable = false; + + if (cpu_has_feature(CPU_FTR_DAWR)) { + /* Don't setup sysfs file for user control on P8 */ + dawr_force_enable = true; + return 0; + } + + if (PVR_VER(mfspr(SPRN_PVR)) == PVR_POWER9) { + /* Turn DAWR off by default, but allow admin to turn it on */ + dawr_force_enable = false; + debugfs_create_file_unsafe("dawr_enable_dangerous", 0600, + powerpc_debugfs_root, + &dawr_force_enable, + &dawr_enable_fops); + } + return 0; +} +arch_initcall(dawr_force_setup); |