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/machdep.h> 13 #include <asm/hvcall.h> 14 15 bool dawr_force_enable; 16 EXPORT_SYMBOL_GPL(dawr_force_enable); 17 18 int set_dawr(int nr, struct arch_hw_breakpoint *brk) 19 { 20 unsigned long dawr, dawrx, mrd; 21 22 dawr = brk->address; 23 24 dawrx = (brk->type & (HW_BRK_TYPE_READ | HW_BRK_TYPE_WRITE)) 25 << (63 - 58); 26 dawrx |= ((brk->type & (HW_BRK_TYPE_TRANSLATE)) >> 2) << (63 - 59); 27 dawrx |= (brk->type & (HW_BRK_TYPE_PRIV_ALL)) >> 3; 28 /* 29 * DAWR length is stored in field MDR bits 48:53. Matches range in 30 * doublewords (64 bits) biased by -1 eg. 0b000000=1DW and 31 * 0b111111=64DW. 32 * brk->hw_len is in bytes. 33 * This aligns up to double word size, shifts and does the bias. 34 */ 35 mrd = ((brk->hw_len + 7) >> 3) - 1; 36 dawrx |= (mrd & 0x3f) << (63 - 53); 37 38 if (ppc_md.set_dawr) 39 return ppc_md.set_dawr(nr, dawr, dawrx); 40 41 if (nr == 0) { 42 mtspr(SPRN_DAWR0, dawr); 43 mtspr(SPRN_DAWRX0, dawrx); 44 } else { 45 mtspr(SPRN_DAWR1, dawr); 46 mtspr(SPRN_DAWRX1, dawrx); 47 } 48 49 return 0; 50 } 51 52 static void disable_dawrs_cb(void *info) 53 { 54 struct arch_hw_breakpoint null_brk = {0}; 55 int i; 56 57 for (i = 0; i < nr_wp_slots(); i++) 58 set_dawr(i, &null_brk); 59 } 60 61 static ssize_t dawr_write_file_bool(struct file *file, 62 const char __user *user_buf, 63 size_t count, loff_t *ppos) 64 { 65 struct arch_hw_breakpoint null_brk = {0}; 66 size_t rc; 67 68 /* Send error to user if they hypervisor won't allow us to write DAWR */ 69 if (!dawr_force_enable && 70 firmware_has_feature(FW_FEATURE_LPAR) && 71 set_dawr(0, &null_brk) != H_SUCCESS) 72 return -ENODEV; 73 74 rc = debugfs_write_file_bool(file, user_buf, count, ppos); 75 if (rc) 76 return rc; 77 78 /* If we are clearing, make sure all CPUs have the DAWR cleared */ 79 if (!dawr_force_enable) 80 smp_call_function(disable_dawrs_cb, NULL, 0); 81 82 return rc; 83 } 84 85 static const struct file_operations dawr_enable_fops = { 86 .read = debugfs_read_file_bool, 87 .write = dawr_write_file_bool, 88 .open = simple_open, 89 .llseek = default_llseek, 90 }; 91 92 static int __init dawr_force_setup(void) 93 { 94 if (cpu_has_feature(CPU_FTR_DAWR)) { 95 /* Don't setup sysfs file for user control on P8 */ 96 dawr_force_enable = true; 97 return 0; 98 } 99 100 if (PVR_VER(mfspr(SPRN_PVR)) == PVR_POWER9) { 101 /* Turn DAWR off by default, but allow admin to turn it on */ 102 debugfs_create_file_unsafe("dawr_enable_dangerous", 0600, 103 arch_debugfs_dir, 104 &dawr_force_enable, 105 &dawr_enable_fops); 106 } 107 return 0; 108 } 109 arch_initcall(dawr_force_setup); 110