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// SPDX-License-Identifier: GPL-2.0+
/*
* DAWR infrastructure
*
* Copyright 2019, Michael Neuling, IBM Corporation.
*/
#include <linux/types.h>
#include <linux/export.h>
#include <linux/fs.h>
#include <linux/debugfs.h>
#include <asm/debugfs.h>
#include <asm/machdep.h>
#include <asm/hvcall.h>
bool dawr_force_enable;
EXPORT_SYMBOL_GPL(dawr_force_enable);
int set_dawr(int nr, struct arch_hw_breakpoint *brk)
{
unsigned long dawr, dawrx, mrd;
dawr = brk->address;
dawrx = (brk->type & (HW_BRK_TYPE_READ | HW_BRK_TYPE_WRITE))
<< (63 - 58);
dawrx |= ((brk->type & (HW_BRK_TYPE_TRANSLATE)) >> 2) << (63 - 59);
dawrx |= (brk->type & (HW_BRK_TYPE_PRIV_ALL)) >> 3;
/*
* DAWR length is stored in field MDR bits 48:53. Matches range in
* doublewords (64 bits) baised by -1 eg. 0b000000=1DW and
* 0b111111=64DW.
* brk->hw_len is in bytes.
* This aligns up to double word size, shifts and does the bias.
*/
mrd = ((brk->hw_len + 7) >> 3) - 1;
dawrx |= (mrd & 0x3f) << (63 - 53);
if (ppc_md.set_dawr)
return ppc_md.set_dawr(nr, dawr, dawrx);
if (nr == 0) {
mtspr(SPRN_DAWR0, dawr);
mtspr(SPRN_DAWRX0, dawrx);
} else {
mtspr(SPRN_DAWR1, dawr);
mtspr(SPRN_DAWRX1, dawrx);
}
return 0;
}
static void disable_dawrs_cb(void *info)
{
struct arch_hw_breakpoint null_brk = {0};
int i;
for (i = 0; i < nr_wp_slots(); i++)
set_dawr(i, &null_brk);
}
static ssize_t dawr_write_file_bool(struct file *file,
const char __user *user_buf,
size_t count, loff_t *ppos)
{
struct arch_hw_breakpoint null_brk = {0};
size_t rc;
/* Send error to user if they hypervisor won't allow us to write DAWR */
if (!dawr_force_enable &&
firmware_has_feature(FW_FEATURE_LPAR) &&
set_dawr(0, &null_brk) != H_SUCCESS)
return -ENODEV;
rc = debugfs_write_file_bool(file, user_buf, count, ppos);
if (rc)
return rc;
/* If we are clearing, make sure all CPUs have the DAWR cleared */
if (!dawr_force_enable)
smp_call_function(disable_dawrs_cb, NULL, 0);
return rc;
}
static const struct file_operations dawr_enable_fops = {
.read = debugfs_read_file_bool,
.write = dawr_write_file_bool,
.open = simple_open,
.llseek = default_llseek,
};
static int __init dawr_force_setup(void)
{
if (cpu_has_feature(CPU_FTR_DAWR)) {
/* Don't setup sysfs file for user control on P8 */
dawr_force_enable = true;
return 0;
}
if (PVR_VER(mfspr(SPRN_PVR)) == PVR_POWER9) {
/* Turn DAWR off by default, but allow admin to turn it on */
debugfs_create_file_unsafe("dawr_enable_dangerous", 0600,
powerpc_debugfs_root,
&dawr_force_enable,
&dawr_enable_fops);
}
return 0;
}
arch_initcall(dawr_force_setup);
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