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Commit 2347d933 authored by H. Peter Anvin's avatar H. Peter Anvin Committed by Ingo Molnar
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x86: cpuid: allow querying %ecx-sensitive CPUID levels 



After /dev/*/cpuid was introduced, Intel changed the semantics of the
CPUID instruction to be sentitive to %ecx as well as %eax.  This patch
allows querying of %ecx-sensitive levels by placing the %ecx value in
the upper 32 bits of the file position (lower 32 bits always were used
for the %eax value.)

Signed-off-by: default avatarH. Peter Anvin <hpa@zytor.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 71713eee

arch/x86/kernel/cpuid.c

+20 −25
Original line number Original line Diff line number Diff line 
/* ----------------------------------------------------------------------- *

/* ----------------------------------------------------------------------- *

 *

 *

 *   Copyright 2000 H. Peter Anvin - All Rights Reserved

 *   Copyright 2000-2008 H. Peter Anvin - All Rights Reserved

 *

 *

 *   This program is free software; you can redistribute it and/or modify

 *   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

 *   it under the terms of the GNU General Public License as published by
@@ -17,6 +17,10 @@ 
 * and then read in chunks of 16 bytes.  A larger size means multiple

 * and then read in chunks of 16 bytes.  A larger size means multiple

 * reads of consecutive levels.

 * reads of consecutive levels.

 *

 *

 * The lower 32 bits of the file position is used as the incoming %eax,

 * and the upper 32 bits of the file position as the incoming %ecx,

 * the latter intended for "counting" eax levels like eax=4.

 *

 * This driver uses /dev/cpu/%d/cpuid where %d is the minor number, and on

 * This driver uses /dev/cpu/%d/cpuid where %d is the minor number, and on

 * an SMP box will direct the access to CPU %d.

 * an SMP box will direct the access to CPU %d.

 */

 */
@@ -43,27 +47,16 @@ 




static struct class *cpuid_class;

static struct class *cpuid_class;





struct cpuid_command {

struct cpuid_regs {

	u32 reg;

	u32 eax, ebx, ecx, edx;

	u32 *data;

};

};





static void cpuid_smp_cpuid(void *cmd_block)

static void cpuid_smp_cpuid(void *cmd_block)

{

{

	struct cpuid_command *cmd = cmd_block;

	struct cpuid_regs *cmd = (struct cpuid_regs *)cmd_block;



	cpuid(cmd->reg, &cmd->data[0], &cmd->data[1], &cmd->data[2],

		      &cmd->data[3]);

}



static inline void do_cpuid(int cpu, u32 reg, u32 * data)

{

	struct cpuid_command cmd;



	cmd.reg = reg;

	cmd.data = data;





	smp_call_function_single(cpu, cpuid_smp_cpuid, &cmd, 1, 1);

	cpuid_count(cmd->eax, cmd->ecx,

		    &cmd->eax, &cmd->ebx, &cmd->ecx, &cmd->edx);

}

}





static loff_t cpuid_seek(struct file *file, loff_t offset, int orig)

static loff_t cpuid_seek(struct file *file, loff_t offset, int orig)
@@ -93,19 +86,21 @@ static ssize_t cpuid_read(struct file *file, char __user *buf, 
			  size_t count, loff_t * ppos)

			  size_t count, loff_t * ppos)

{

{

	char __user *tmp = buf;

	char __user *tmp = buf;

	u32 data[4];

	struct cpuid_regs cmd;

	u32 reg = *ppos;

	int cpu = iminor(file->f_path.dentry->d_inode);

	int cpu = iminor(file->f_path.dentry->d_inode);

	u64 pos = *ppos;





	if (count % 16)

	if (count % 16)

		return -EINVAL;	/* Invalid chunk size */

		return -EINVAL;	/* Invalid chunk size */





	for (; count; count -= 16) {

	for (; count; count -= 16) {

		do_cpuid(cpu, reg, data);

		cmd.eax = pos;

		if (copy_to_user(tmp, &data, 16))

		cmd.ecx = pos >> 32;

		smp_call_function_single(cpu, cpuid_smp_cpuid, &cmd, 1, 1);

		if (copy_to_user(tmp, &cmd, 16))

			return -EFAULT;

			return -EFAULT;

		tmp += 16;

		tmp += 16;

		*ppos = reg++;

		*ppos = ++pos;

	}

	}





	return tmp - buf;

	return tmp - buf;