| Michael Neuling | a278e7e | 2019-06-04 13:00:37 +1000 | [diff] [blame] | 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->len is in bytes. |
| 34 | * This aligns up to double word size, shifts and does the bias. |
| 35 | */ |
| 36 | mrd = ((brk->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, 0, 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); |