1 // SPDX-License-Identifier: GPL-2.0+
5 * Copyright 2019, Michael Neuling, IBM Corporation.
8 #include <linux/types.h>
9 #include <linux/export.h>
11 #include <linux/debugfs.h>
12 #include <asm/machdep.h>
13 #include <asm/hvcall.h>
14 #include <asm/firmware.h>
16 bool dawr_force_enable;
17 EXPORT_SYMBOL_GPL(dawr_force_enable);
19 int set_dawr(int nr, struct arch_hw_breakpoint *brk)
21 unsigned long dawr, dawrx, mrd;
25 dawrx = (brk->type & (HW_BRK_TYPE_READ | HW_BRK_TYPE_WRITE))
27 dawrx |= ((brk->type & (HW_BRK_TYPE_TRANSLATE)) >> 2) << (63 - 59);
28 dawrx |= (brk->type & (HW_BRK_TYPE_PRIV_ALL)) >> 3;
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
33 * brk->hw_len is in bytes.
34 * This aligns up to double word size, shifts and does the bias.
36 mrd = ((brk->hw_len + 7) >> 3) - 1;
37 dawrx |= (mrd & 0x3f) << (63 - 53);
40 return ppc_md.set_dawr(nr, dawr, dawrx);
43 mtspr(SPRN_DAWR0, dawr);
44 mtspr(SPRN_DAWRX0, dawrx);
46 mtspr(SPRN_DAWR1, dawr);
47 mtspr(SPRN_DAWRX1, dawrx);
53 static void disable_dawrs_cb(void *info)
55 struct arch_hw_breakpoint null_brk = {0};
58 for (i = 0; i < nr_wp_slots(); i++)
59 set_dawr(i, &null_brk);
62 static ssize_t dawr_write_file_bool(struct file *file,
63 const char __user *user_buf,
64 size_t count, loff_t *ppos)
66 struct arch_hw_breakpoint null_brk = {0};
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)
75 rc = debugfs_write_file_bool(file, user_buf, count, ppos);
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);
86 static const struct file_operations dawr_enable_fops = {
87 .read = debugfs_read_file_bool,
88 .write = dawr_write_file_bool,
90 .llseek = default_llseek,
93 static int __init dawr_force_setup(void)
95 if (cpu_has_feature(CPU_FTR_DAWR)) {
96 /* Don't setup sysfs file for user control on P8 */
97 dawr_force_enable = true;
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,
110 arch_initcall(dawr_force_setup);