2006-09-07 02:50:58

by Shaohua Li

Subject: [PATCH] x86 microcode: don't check the size

IA32 manual says if micorcode update's size is 0, then the size is
default size (2048 bytes). But this doesn't suggest all microcode
update's size should be above 2048 bytes to me. We actually had a
microcode update whose size is 1024 bytes. The patch just removed the
check.

Signed-off-by: Shaohua Li <[email protected]>

---
work/src/linux-2.6.18-rc5-mm1/arch/i386/kernel/microcode.c | 14 ++-----------
1 files changed, 3 insertions(+), 11 deletions(-)

Index: root/work/src/linux-2.6.18-rc5-mm1/arch/i386/kernel/microcode.c
===================================================================
--- root.orig/work/src/linux-2.6.18-rc5-mm1/arch/i386/kernel/microcode.c 2006-09-06 06:51:03.000000000 +0800
+++ root/work/src/linux-2.6.18-rc5-mm1/arch/i386/kernel/microcode.c 2006-09-06 08:20:35.000000000 +0800
@@ -187,8 +187,7 @@ static int microcode_sanity_check(void *

total_size = get_totalsize(mc_header);
data_size = get_datasize(mc_header);
- if ((data_size + MC_HEADER_SIZE > total_size)
- || (data_size < DEFAULT_UCODE_DATASIZE)) {
+ if (data_size + MC_HEADER_SIZE > total_size) {
printk(KERN_ERR "microcode: error! "
"Bad data size in microcode data file\n");
return -EINVAL;
@@ -365,8 +364,7 @@ static long get_next_ucode(void **mc, lo
return -EFAULT;
}
total_size = get_totalsize(&mc_header);
- if ((offset + total_size > user_buffer_size)
- || (total_size < DEFAULT_UCODE_TOTALSIZE)) {
+ if (offset + total_size > user_buffer_size) {
printk(KERN_ERR "microcode: error! Bad total size in microcode "
"data file\n");
return -EINVAL;
@@ -432,11 +430,6 @@ static ssize_t microcode_write (struct f
{
ssize_t ret;

- if (len < DEFAULT_UCODE_TOTALSIZE) {
- printk(KERN_ERR "microcode: not enough data\n");
- return -EINVAL;
- }
-
if ((len >> PAGE_SHIFT) > num_physpages) {
printk(KERN_ERR "microcode: too much data (max %ld pages)\n", num_physpages);
return -EINVAL;
@@ -508,8 +501,7 @@ static long get_next_ucode_from_buffer(v
mc_header = (microcode_header_t *)(buf + offset);
total_size = get_totalsize(mc_header);

- if ((offset + total_size > size)
- || (total_size < DEFAULT_UCODE_TOTALSIZE)) {
+ if (offset + total_size > size) {
printk(KERN_ERR "microcode: error! Bad data in microcode data file\n");
return -EINVAL;
}

2006-09-07 04:18:53

by Jeff Garzik

Subject: Re: [PATCH] x86 microcode: don't check the size

Shaohua Li wrote:
> IA32 manual says if micorcode update's size is 0, then the size is
> default size (2048 bytes). But this doesn't suggest all microcode
> update's size should be above 2048 bytes to me. We actually had a
> microcode update whose size is 1024 bytes. The patch just removed the
> check.
>
> Signed-off-by: Shaohua Li <[email protected]>

Why not explicitly check for zero, rather than removing the questionable
less-than test? The default size logic hasn't disappeared...

Jeff

2006-09-07 05:18:30

by Shaohua Li

Subject: Re: [PATCH] x86 microcode: don't check the size

On Thu, 2006-09-07 at 00:18 -0400, Jeff Garzik wrote:
> Shaohua Li wrote:
> > IA32 manual says if micorcode update's size is 0, then the size is
> > default size (2048 bytes). But this doesn't suggest all microcode
> > update's size should be above 2048 bytes to me. We actually had a
> > microcode update whose size is 1024 bytes. The patch just removed the
> > check.
> >
> > Signed-off-by: Shaohua Li <[email protected]>
>
> Why not explicitly check for zero, rather than removing the questionable
> less-than test? The default size logic hasn't disappeared...
We just don't want the default size check. If the size is 0, we still
need use default size. The patch is just for those whose size isn't 0
but smaller than default size.

Thanks,
Shaohua