1 // SPDX-License-Identifier: GPL-2.0+ 2 /* 3 * DAWR infrastructure 4 * 5 * Copyright 2019, Michael Neuling, IBM Corporation. 6 */ 7 8 #include <linux/types.h> 9 #include <linux/export.h> 10 #include <linux/fs.h> 11 #include <linux/debugfs.h> 12 #include <asm/debugfs.h> 13 #include <asm/machdep.h> 14 #include <asm/hvcall.h> 15 16 bool dawr_force_enable; 17 EXPORT_SYMBOL_GPL(dawr_force_enable); 18 19 int set_dawr(struct arch_hw_breakpoint *brk) 20 { 21 unsigned long dawr, dawrx, mrd; 22 23 dawr = brk->address; 24 25 dawrx = (brk->type & (HW_BRK_TYPE_READ | HW_BRK_TYPE_WRITE)) 26 << (63 - 58); 27 dawrx |= ((brk->type & (HW_BRK_TYPE_TRANSLATE)) >> 2) << (63 - 59); 28 dawrx |= (brk->type & (HW_BRK_TYPE_PRIV_ALL)) >> 3; 29 /* 30 * DAWR length is stored in field MDR bits 48:53. Matches range in 31 * doublewords (64 bits) baised by -1 eg. 0b000000=1DW and 32 * 0b111111=64DW. 33 * brk->hw_len is in bytes. 34 * This aligns up to double word size, shifts and does the bias. 35 */ 36 mrd = ((brk->hw_len + 7) >> 3) - 1; 37 dawrx |= (mrd & 0x3f) << (63 - 53); 38 39 if (ppc_md.set_dawr) 40 return ppc_md.set_dawr(dawr, dawrx); 41 42 mtspr(SPRN_DAWR, dawr); 43 mtspr(SPRN_DAWRX, dawrx); 44 45 return 0; 46 } 47 48 static void set_dawr_cb(void *info) 49 { 50 set_dawr(info); 51 } 52 53 static ssize_t dawr_write_file_bool(struct file *file, 54 const char __user *user_buf, 55 size_t count, loff_t *ppos) 56 { 57 struct arch_hw_breakpoint null_brk = {0}; 58 size_t rc; 59 60 /* Send error to user if they hypervisor won't allow us to write DAWR */ 61 if (!dawr_force_enable && 62 firmware_has_feature(FW_FEATURE_LPAR) && 63 set_dawr(&null_brk) != H_SUCCESS) 64 return -ENODEV; 65 66 rc = debugfs_write_file_bool(file, user_buf, count, ppos); 67 if (rc) 68 return rc; 69 70 /* If we are clearing, make sure all CPUs have the DAWR cleared */ 71 if (!dawr_force_enable) 72 smp_call_function(set_dawr_cb, &null_brk, 0); 73 74 return rc; 75 } 76 77 static const struct file_operations dawr_enable_fops = { 78 .read = debugfs_read_file_bool, 79 .write = dawr_write_file_bool, 80 .open = simple_open, 81 .llseek = default_llseek, 82 }; 83 84 static int __init dawr_force_setup(void) 85 { 86 if (cpu_has_feature(CPU_FTR_DAWR)) { 87 /* Don't setup sysfs file for user control on P8 */ 88 dawr_force_enable = true; 89 return 0; 90 } 91 92 if (PVR_VER(mfspr(SPRN_PVR)) == PVR_POWER9) { 93 /* Turn DAWR off by default, but allow admin to turn it on */ 94 debugfs_create_file_unsafe("dawr_enable_dangerous", 0600, 95 powerpc_debugfs_root, 96 &dawr_force_enable, 97 &dawr_enable_fops); 98 } 99 return 0; 100 } 101 arch_initcall(dawr_force_setup); 102