cregit-Linux how code gets into the kernel

Release 4.11 arch/x86/kernel/cpu/intel_rdt_schemata.c

/*
 * Resource Director Technology(RDT)
 * - Cache Allocation code.
 *
 * Copyright (C) 2016 Intel Corporation
 *
 * Authors:
 *    Fenghua Yu <fenghua.yu@intel.com>
 *    Tony Luck <tony.luck@intel.com>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * More information about RDT be found in the Intel (R) x86 Architecture
 * Software Developer Manual June 2016, volume 3, section 17.17.
 */


#define pr_fmt(fmt)	KBUILD_MODNAME ": " fmt

#include <linux/kernfs.h>
#include <linux/seq_file.h>
#include <linux/slab.h>
#include <asm/intel_rdt.h>

/*
 * Check whether a cache bit mask is valid. The SDM says:
 *      Please note that all (and only) contiguous '1' combinations
 *      are allowed (e.g. FFFFH, 0FF0H, 003CH, etc.).
 * Additionally Haswell requires at least two bits set.
 */

static bool cbm_validate(unsigned long var, struct rdt_resource *r) { unsigned long first_bit, zero_bit; if (var == 0 || var > r->max_cbm) return false; first_bit = find_first_bit(&var, r->cbm_len); zero_bit = find_next_zero_bit(&var, r->cbm_len, first_bit); if (find_next_bit(&var, r->cbm_len, zero_bit) < r->cbm_len) return false; if ((zero_bit - first_bit) < r->min_cbm_bits) return false; return true; }

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/* * Read one cache bit mask (hex). Check that it is valid for the current * resource type. */
static int parse_cbm(char *buf, struct rdt_resource *r) { unsigned long data; int ret; ret = kstrtoul(buf, 16, &data); if (ret) return ret; if (!cbm_validate(data, r)) return -EINVAL; r->tmp_cbms[r->num_tmp_cbms++] = data; return 0; }

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/* * For each domain in this resource we expect to find a series of: * id=mask * separated by ";". The "id" is in decimal, and must appear in the * right order. */
static int parse_line(char *line, struct rdt_resource *r) { char *dom = NULL, *id; struct rdt_domain *d; unsigned long dom_id; list_for_each_entry(d, &r->domains, list) { dom = strsep(&line, ";"); if (!dom) return -EINVAL; id = strsep(&dom, "="); if (kstrtoul(id, 10, &dom_id) || dom_id != d->id) return -EINVAL; if (parse_cbm(dom, r)) return -EINVAL; } /* Any garbage at the end of the line? */ if (line && line[0]) return -EINVAL; return 0; }

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static int update_domains(struct rdt_resource *r, int closid) { struct msr_param msr_param; cpumask_var_t cpu_mask; struct rdt_domain *d; int cpu, idx = 0; if (!zalloc_cpumask_var(&cpu_mask, GFP_KERNEL)) return -ENOMEM; msr_param.low = closid; msr_param.high = msr_param.low + 1; msr_param.res = r; list_for_each_entry(d, &r->domains, list) { cpumask_set_cpu(cpumask_any(&d->cpu_mask), cpu_mask); d->cbm[msr_param.low] = r->tmp_cbms[idx++]; } cpu = get_cpu(); /* Update CBM on this cpu if it's in cpu_mask. */ if (cpumask_test_cpu(cpu, cpu_mask)) rdt_cbm_update(&msr_param); /* Update CBM on other cpus. */ smp_call_function_many(cpu_mask, rdt_cbm_update, &msr_param, 1); put_cpu(); free_cpumask_var(cpu_mask); return 0; }

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ssize_t rdtgroup_schemata_write(struct kernfs_open_file *of, char *buf, size_t nbytes, loff_t off) { struct rdtgroup *rdtgrp; struct rdt_resource *r; char *tok, *resname; int closid, ret = 0; u32 *l3_cbms = NULL; /* Valid input requires a trailing newline */ if (nbytes == 0 || buf[nbytes - 1] != '\n') return -EINVAL; buf[nbytes - 1] = '\0'; rdtgrp = rdtgroup_kn_lock_live(of->kn); if (!rdtgrp) { rdtgroup_kn_unlock(of->kn); return -ENOENT; } closid = rdtgrp->closid; /* get scratch space to save all the masks while we validate input */ for_each_enabled_rdt_resource(r) { r->tmp_cbms = kcalloc(r->num_domains, sizeof(*l3_cbms), GFP_KERNEL); if (!r->tmp_cbms) { ret = -ENOMEM; goto out; } r->num_tmp_cbms = 0; } while ((tok = strsep(&buf, "\n")) != NULL) { resname = strsep(&tok, ":"); if (!tok) { ret = -EINVAL; goto out; } for_each_enabled_rdt_resource(r) { if (!strcmp(resname, r->name) && closid < r->num_closid) { ret = parse_line(tok, r); if (ret) goto out; break; } } if (!r->name) { ret = -EINVAL; goto out; } } /* Did the parser find all the masks we need? */ for_each_enabled_rdt_resource(r) { if (r->num_tmp_cbms != r->num_domains) { ret = -EINVAL; goto out; } } for_each_enabled_rdt_resource(r) { ret = update_domains(r, closid); if (ret) goto out; } out: for_each_enabled_rdt_resource(r) { kfree(r->tmp_cbms); r->tmp_cbms = NULL; } rdtgroup_kn_unlock(of->kn); return ret ?: nbytes; }

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static void show_doms(struct seq_file *s, struct rdt_resource *r, int closid) { struct rdt_domain *dom; bool sep = false; seq_printf(s, "%s:", r->name); list_for_each_entry(dom, &r->domains, list) { if (sep) seq_puts(s, ";"); seq_printf(s, "%d=%x", dom->id, dom->cbm[closid]); sep = true; } seq_puts(s, "\n"); }

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int rdtgroup_schemata_show(struct kernfs_open_file *of, struct seq_file *s, void *v) { struct rdtgroup *rdtgrp; struct rdt_resource *r; int closid, ret = 0; rdtgrp = rdtgroup_kn_lock_live(of->kn); if (rdtgrp) { closid = rdtgrp->closid; for_each_enabled_rdt_resource(r) { if (closid < r->num_closid) show_doms(s, r, closid); } } else { ret = -ENOENT; } rdtgroup_kn_unlock(of->kn); return ret; }

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