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
 16bool dawr_force_enable;
 17EXPORT_SYMBOL_GPL(dawr_force_enable);
 18
 19int 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) 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(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
 53static 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
 62static 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
 86static 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
 93static 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					   powerpc_debugfs_root,
105					   &dawr_force_enable,
106					   &dawr_enable_fops);
107	}
108	return 0;
109}
110arch_initcall(dawr_force_setup);