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x86: cpuid: allow querying %ecx-sensitive CPUID levels

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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: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
H. Peter Anvin 2008-02-04 16:47:59 +01:00 committed by Ingo Molnar
parent 71713eeed0
commit 2347d933b1
1 changed files with 20 additions and 25 deletions
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45
arch/x86/kernel/cpuid.c
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@ -1,6 +1,6 @@
/* ----------------------------------------------------------------------- *
*
* 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
* 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
* 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
* an SMP box will direct the access to CPU %d.
*/
@ -43,27 +47,16 @@
static struct class *cpuid_class;
struct cpuid_command {
u32 reg;
u32 *data;
struct cpuid_regs {
u32 eax, ebx, ecx, edx;
};
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)
@ -93,19 +86,21 @@ static ssize_t cpuid_read(struct file *file, char __user *buf,
size_t count, loff_t * ppos)
{
char __user *tmp = buf;
u32 data[4];
u32 reg = *ppos;
struct cpuid_regs cmd;
int cpu = iminor(file->f_path.dentry->d_inode);
u64 pos = *ppos;
if (count % 16)
return -EINVAL; /* Invalid chunk size */
for (; count; count -= 16) {
do_cpuid(cpu, reg, data);
if (copy_to_user(tmp, &data, 16))
cmd.eax = pos;
cmd.ecx = pos >> 32;
smp_call_function_single(cpu, cpuid_smp_cpuid, &cmd, 1, 1);
if (copy_to_user(tmp, &cmd, 16))
return -EFAULT;
tmp += 16;
*ppos = reg++;
*ppos = ++pos;
}
return tmp - buf;
@ -193,7 +188,7 @@ static int __init cpuid_init(void)
}
for_each_online_cpu(i) {
err = cpuid_device_create(i);
if (err != 0)
if (err != 0)
goto out_class;
}
register_hotcpu_notifier(&cpuid_class_cpu_notifier);
@ -208,7 +203,7 @@ out_class:
}
class_destroy(cpuid_class);
out_chrdev:
unregister_chrdev(CPUID_MAJOR, "cpu/cpuid");
unregister_chrdev(CPUID_MAJOR, "cpu/cpuid");
out:
return err;
}