// SPDX-License-Identifier: GPL-2.0+ /* * DAWR infrastructure * * Copyright 2019, Michael Neuling, IBM Corporation. */ #include <linux/types.h> #include <linux/export.h> #include <linux/fs.h> #include <linux/debugfs.h> #include <asm/debugfs.h> #include <asm/machdep.h> #include <asm/hvcall.h> bool dawr_force_enable; EXPORT_SYMBOL_GPL(dawr_force_enable); int set_dawr(struct arch_hw_breakpoint *brk) { unsigned long dawr, dawrx, mrd; dawr = brk->address; dawrx = (brk->type & (HW_BRK_TYPE_READ | HW_BRK_TYPE_WRITE)) << (63 - 58); dawrx |= ((brk->type & (HW_BRK_TYPE_TRANSLATE)) >> 2) << (63 - 59); dawrx |= (brk->type & (HW_BRK_TYPE_PRIV_ALL)) >> 3; /* * DAWR length is stored in field MDR bits 48:53. Matches range in * doublewords (64 bits) baised by -1 eg. 0b000000=1DW and * 0b111111=64DW. * brk->hw_len is in bytes. * This aligns up to double word size, shifts and does the bias. */ mrd = ((brk->hw_len + 7) >> 3) - 1; dawrx |= (mrd & 0x3f) << (63 - 53); if (ppc_md.set_dawr) return ppc_md.set_dawr(dawr, dawrx); mtspr(SPRN_DAWR, dawr); mtspr(SPRN_DAWRX, dawrx); return 0; } static void set_dawr_cb(void *info) { set_dawr(info); } 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}; 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 -ENODEV; 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(set_dawr_cb, &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) { 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 */ debugfs_create_file_unsafe("dawr_enable_dangerous", 0600, powerpc_debugfs_root, &dawr_force_enable, &dawr_enable_fops); } return 0; } arch_initcall(dawr_force_setup);