Re: [RFC PATCH v4 24/28] x86: Access the setup data through debugfs decrypted

Tom Lendacky
2017-03-17T19:54:56Z

On 3/8/2017 1:04 AM, Dave Young wrote:
> On 02/16/17 at 09:47am, Tom Lendacky wrote:
>> Use memremap() to map the setup data. This simplifies the code and will
>> make the appropriate decision as to whether a RAM remapping can be done
>> or if a fallback to ioremap_cache() is needed (which includes checking
>> PageHighMem).
>>
>> Signed-off-by: Tom Lendacky <thomas.lendacky-5C7GfCeVMHo@public.gmane.org>
>> ---
>> arch/x86/kernel/kdebugfs.c | 30 +++++++++++-------------------
>> 1 file changed, 11 insertions(+), 19 deletions(-)
>>
>> diff --git a/arch/x86/kernel/kdebugfs.c b/arch/x86/kernel/kdebugfs.c
>> index bdb83e4..c3d354d 100644
>> --- a/arch/x86/kernel/kdebugfs.c
>> +++ b/arch/x86/kernel/kdebugfs.c
>> @@ -48,17 +48,13 @@ static ssize_t setup_data_read(struct file *file, char __user *user_buf,
>>
>> pa = node->paddr + sizeof(struct setup_data) + pos;
>> pg = pfn_to_page((pa + count - 1) >> PAGE_SHIFT);
>> - if (PageHighMem(pg)) {
>> - p = ioremap_cache(pa, count);
>> - if (!p)
>> - return -ENXIO;
>> - } else
>> - p = __va(pa);
>> + p = memremap(pa, count, MEMREMAP_WB);
>> + if (!p)
>> + return -ENXIO;
>
> -ENOMEM looks better for memremap, ditto for other places..

Makes sense, I'll change them.

Thanks,
Tom

>
>>
>> remain = copy_to_user(user_buf, p, count);
>>
>> - if (PageHighMem(pg))
>> - iounmap(p);
>> + memunmap(p);
>>
>> if (remain)
>> return -EFAULT;
>> @@ -127,15 +123,12 @@ static int __init create_setup_data_nodes(struct dentry *parent)
>> }
>>
>> pg = pfn_to_page((pa_data+sizeof(*data)-1) >> PAGE_SHIFT);
>> - if (PageHighMem(pg)) {
>> - data = ioremap_cache(pa_data, sizeof(*data));
>> - if (!data) {
>> - kfree(node);
>> - error = -ENXIO;
>> - goto err_dir;
>> - }
>> - } else
>> - data = __va(pa_data);
>> + data = memremap(pa_data, sizeof(*data), MEMREMAP_WB);
>> + if (!data) {
>> + kfree(node);
>> + error = -ENXIO;
>> + goto err_dir;
>> + }
>>
>> node->paddr = pa_data;
>> node->type = data->type;
>> @@ -143,8 +136,7 @@ static int __init create_setup_data_nodes(struct dentry *parent)
>> error = create_setup_data_node(d, no, node);
>> pa_data = data->next;
>>
>> - if (PageHighMem(pg))
>> - iounmap(data);
>> + memunmap(data);
>> if (error)
>> goto err_dir;
>> no++;
>>
>
> Thanks
> Dave
>