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 #include <asm/firmware.h> 15 16 bool dawr_force_enable; 17 EXPORT_SYMBOL_GPL(dawr_force_enable); 18 19 int set_dawr(int nr, 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) biased 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(nr, dawr, dawrx); 41 42 if (nr == 0) { 43 mtspr(SPRN_DAWR0, dawr); 44 mtspr(SPRN_DAWRX0, dawrx); 45 } else { 46 mtspr(SPRN_DAWR1, dawr); 47 mtspr(SPRN_DAWRX1, dawrx); 48 } 49 50 return 0; 51 } 52 53 static void disable_dawrs_cb(void *info) 54 { 55 struct arch_hw_breakpoint null_brk = {0}; 56 int i; 57 58 for (i = 0; i < nr_wp_slots(); i++) 59 set_dawr(i, &null_brk); 60 } 61 62 static ssize_t dawr_write_file_bool(struct file *file, 63 const char __user *user_buf, 64 size_t count, loff_t *ppos) 65 { 66 struct arch_hw_breakpoint null_brk = {0}; 67 size_t rc; 68 69 /* Send error to user if they hypervisor won't allow us to write DAWR */ 70 if (!dawr_force_enable && 71 firmware_has_feature(FW_FEATURE_LPAR) && 72 set_dawr(0, &null_brk) != H_SUCCESS) 73 return -ENODEV; 74 75 rc = debugfs_write_file_bool(file, user_buf, count, ppos); 76 if (rc) 77 return rc; 78 79 /* If we are clearing, make sure all CPUs have the DAWR cleared */ 80 if (!dawr_force_enable) 81 smp_call_function(disable_dawrs_cb, NULL, 0); 82 83 return rc; 84 } 85 86 static const struct file_operations dawr_enable_fops = { 87 .read = debugfs_read_file_bool, 88 .write = dawr_write_file_bool, 89 .open = simple_open, 90 .llseek = default_llseek, 91 }; 92 93 static int __init dawr_force_setup(void) 94 { 95 if (cpu_has_feature(CPU_FTR_DAWR)) { 96 /* Don't setup sysfs file for user control on P8 */ 97 dawr_force_enable = true; 98 return 0; 99 } 100 101 if (PVR_VER(mfspr(SPRN_PVR)) == PVR_POWER9) { 102 /* Turn DAWR off by default, but allow admin to turn it on */ 103 debugfs_create_file_unsafe("dawr_enable_dangerous", 0600, 104 arch_debugfs_dir, 105 &dawr_force_enable, 106 &dawr_enable_fops); 107 } 108 return 0; 109 } 110 arch_initcall(dawr_force_setup); 111