[PATCH v5 32/32] x86/mm: Add support to make use of Secure Memory Encryption
thomas.lendacky at amd.com
Tue May 30 08:46:22 PDT 2017
On 5/19/2017 6:30 AM, Borislav Petkov wrote:
> On Fri, Apr 21, 2017 at 01:56:13PM -0500, Tom Lendacky wrote:
>> On 4/18/2017 4:22 PM, Tom Lendacky wrote:
>>> Add support to check if SME has been enabled and if memory encryption
>>> should be activated (checking of command line option based on the
>>> configuration of the default state). If memory encryption is to be
>>> activated, then the encryption mask is set and the kernel is encrypted
>>> "in place."
>>> Signed-off-by: Tom Lendacky <thomas.lendacky at amd.com>
>>> arch/x86/kernel/head_64.S | 1 +
>>> arch/x86/mm/mem_encrypt.c | 83 +++++++++++++++++++++++++++++++++++++++++++--
>>> 2 files changed, 80 insertions(+), 4 deletions(-)
>>> -unsigned long __init sme_enable(void)
>>> +unsigned long __init sme_enable(struct boot_params *bp)
>>> + const char *cmdline_ptr, *cmdline_arg, *cmdline_on, *cmdline_off;
>>> + unsigned int eax, ebx, ecx, edx;
>>> + unsigned long me_mask;
>>> + bool active_by_default;
>>> + char buffer;
>> So it turns out that when KASLR is enabled (CONFIG_RAMDOMIZE_BASE=y)
>> the stack-protector support causes issues with this function because
> What issues?
The stack protection support makes use of the gs segment register and
at this point not everything is setup properly to allow it to work,
so it segfaults.
>> it is called so early. I can get past it by adding:
>> CFLAGS_mem_encrypt.o := $(nostackp)
>> in the arch/x86/mm/Makefile, but that obviously eliminates the support
>> for the whole file. Would it be better to split out the sme_enable()
>> and other boot routines into a separate file or just apply the
>> $(nostackp) to the whole file?
> Josh might have a better idea here... CCed.
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