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: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/arch/x86/kernel/cpuid.c b/arch/x86/kernel/cpuid.c
index a63432d..c10ebc4 100644
--- a/arch/x86/kernel/cpuid.c
+++ b/arch/x86/kernel/cpuid.c
@@ -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 @@
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 @@
}
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 @@
}
class_destroy(cpuid_class);
out_chrdev:
- unregister_chrdev(CPUID_MAJOR, "cpu/cpuid");
+ unregister_chrdev(CPUID_MAJOR, "cpu/cpuid");
out:
return err;
}
