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23 October 2021, 00:29:24 UTC
Revision 573b3aa6940661dc50c383213d428c27df78be7c authored by Yonghong Song on 30 July 2018, 15:49:03 UTC, committed by Daniel Borkmann on 30 July 2018, 22:37:09 UTC 
tools/bpftool: fix a percpu_array map dump problem
 
I hit the following problem when I tried to use bpftool
to dump a percpu array.

  $ sudo ./bpftool map show
  61: percpu_array  name stub  flags 0x0
          key 4B  value 4B  max_entries 1  memlock 4096B
  ...
  $ sudo ./bpftool map dump id 61
  bpftool: malloc.c:2406: sysmalloc: Assertion
  `(old_top == initial_top (av) && old_size == 0) || \
   ((unsigned long) (old_size) >= MINSIZE && \
   prev_inuse (old_top) && \
   ((unsigned long) old_end & (pagesize - 1)) == 0)'
  failed.
  Aborted

Further debugging revealed that this is due to
miscommunication between bpftool and kernel.
For example, for the above percpu_array with value size of 4B.
The map info returned to user space has value size of 4B.

In bpftool, the values array for lookup is allocated like:
   info->value_size * get_possible_cpus() = 4 * get_possible_cpus()
In kernel (kernel/bpf/syscall.c), the values array size is
rounded up to multiple of 8.
   round_up(map->value_size, 8) * num_possible_cpus()
   = 8 * num_possible_cpus()
So when kernel copies the values to user buffer, the kernel will
overwrite beyond user buffer boundary.

This patch fixed the issue by allocating and stepping through
percpu map value array properly in bpftool.

Fixes: 71bb428fe2c19 ("tools: bpf: add bpftool")
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
1 parent 61f4b23
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Tip revision: 573b3aa6940661dc50c383213d428c27df78be7c authored by Yonghong Song on 30 July 2018, 15:49:03 UTC
tools/bpftool: fix a percpu_array map dump problem
Tip revision: 573b3aa
cppc_acpi.h 
/*
 * CPPC (Collaborative Processor Performance Control) methods used
 * by CPUfreq drivers.
 *
 * (C) Copyright 2014, 2015 Linaro Ltd.
 * Author: Ashwin Chaugule <ashwin.chaugule@linaro.org>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; version 2
 * of the License.
 */

#ifndef _CPPC_ACPI_H
#define _CPPC_ACPI_H

#include <linux/acpi.h>
#include <linux/types.h>

#include <acpi/pcc.h>
#include <acpi/processor.h>

/* Support CPPCv2 and CPPCv3  */
#define CPPC_V2_REV	2
#define CPPC_V3_REV	3
#define CPPC_V2_NUM_ENT	21
#define CPPC_V3_NUM_ENT	23

#define PCC_CMD_COMPLETE_MASK	(1 << 0)
#define PCC_ERROR_MASK		(1 << 2)

#define MAX_CPC_REG_ENT 21

/* CPPC specific PCC commands. */
#define	CMD_READ 0
#define	CMD_WRITE 1

/* Each register has the folowing format. */
struct cpc_reg {
	u8 descriptor;
	u16 length;
	u8 space_id;
	u8 bit_width;
	u8 bit_offset;
	u8 access_width;
	u64 __iomem address;
} __packed;

/*
 * Each entry in the CPC table is either
 * of type ACPI_TYPE_BUFFER or
 * ACPI_TYPE_INTEGER.
 */
struct cpc_register_resource {
	acpi_object_type type;
	u64 __iomem *sys_mem_vaddr;
	union {
		struct cpc_reg reg;
		u64 int_value;
	} cpc_entry;
};

/* Container to hold the CPC details for each CPU */
struct cpc_desc {
	int num_entries;
	int version;
	int cpu_id;
	int write_cmd_status;
	int write_cmd_id;
	struct cpc_register_resource cpc_regs[MAX_CPC_REG_ENT];
	struct acpi_psd_package domain_info;
	struct kobject kobj;
};

/* These are indexes into the per-cpu cpc_regs[]. Order is important. */
enum cppc_regs {
	HIGHEST_PERF,
	NOMINAL_PERF,
	LOW_NON_LINEAR_PERF,
	LOWEST_PERF,
	GUARANTEED_PERF,
	DESIRED_PERF,
	MIN_PERF,
	MAX_PERF,
	PERF_REDUC_TOLERANCE,
	TIME_WINDOW,
	CTR_WRAP_TIME,
	REFERENCE_CTR,
	DELIVERED_CTR,
	PERF_LIMITED,
	ENABLE,
	AUTO_SEL_ENABLE,
	AUTO_ACT_WINDOW,
	ENERGY_PERF,
	REFERENCE_PERF,
	LOWEST_FREQ,
	NOMINAL_FREQ,
};

/*
 * Categorization of registers as described
 * in the ACPI v.5.1 spec.
 * XXX: Only filling up ones which are used by governors
 * today.
 */
struct cppc_perf_caps {
	u32 highest_perf;
	u32 nominal_perf;
	u32 lowest_perf;
	u32 lowest_nonlinear_perf;
	u32 lowest_freq;
	u32 nominal_freq;
};

struct cppc_perf_ctrls {
	u32 max_perf;
	u32 min_perf;
	u32 desired_perf;
};

struct cppc_perf_fb_ctrs {
	u64 reference;
	u64 delivered;
	u64 reference_perf;
	u64 wraparound_time;
};

/* Per CPU container for runtime CPPC management. */
struct cppc_cpudata {
	int cpu;
	struct cppc_perf_caps perf_caps;
	struct cppc_perf_ctrls perf_ctrls;
	struct cppc_perf_fb_ctrs perf_fb_ctrs;
	struct cpufreq_policy *cur_policy;
	unsigned int shared_type;
	cpumask_var_t shared_cpu_map;
};

extern int cppc_get_perf_ctrs(int cpu, struct cppc_perf_fb_ctrs *perf_fb_ctrs);
extern int cppc_set_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls);
extern int cppc_get_perf_caps(int cpu, struct cppc_perf_caps *caps);
extern int acpi_get_psd_map(struct cppc_cpudata **);
extern unsigned int cppc_get_transition_latency(int cpu);

#endif /* _CPPC_ACPI_H*/
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