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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/machdep.h>
- #include <asm/hvcall.h>
- #include <asm/firmware.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) biased 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,
- arch_debugfs_dir,
- &dawr_force_enable,
- &dawr_enable_fops);
- }
- return 0;
- }
- arch_initcall(dawr_force_setup);
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