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x86/mm: Add support to encrypt the kernel in-place
Add the support to encrypt the kernel in-place. This is done by creating new page mappings for the kernel - a decrypted write-protected mapping and an encrypted mapping. The kernel is encrypted by copying it through a temporary buffer. Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Cc: Alexander Potapenko <glider@google.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Borislav Petkov <bp@alien8.de> Cc: Brijesh Singh <brijesh.singh@amd.com> Cc: Dave Young <dyoung@redhat.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Matt Fleming <matt@codeblueprint.co.uk> Cc: Michael S. Tsirkin <mst@redhat.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Radim Krčmář <rkrcmar@redhat.com> Cc: Rik van Riel <riel@redhat.com> Cc: Toshimitsu Kani <toshi.kani@hpe.com> Cc: kasan-dev@googlegroups.com Cc: kvm@vger.kernel.org Cc: linux-arch@vger.kernel.org Cc: linux-doc@vger.kernel.org Cc: linux-efi@vger.kernel.org Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/c039bf9412ef95e1e6bf4fdf8facab95e00c717b.1500319216.git.thomas.lendacky@amd.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Tom Lendacky
Ingo Molnar
parent
db516997a9
commit
6ebcb06071
4 changed files with 466 additions and 0 deletions
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@ -21,6 +21,12 @@
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extern unsigned long sme_me_mask;
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extern unsigned long sme_me_mask;
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void sme_encrypt_execute(unsigned long encrypted_kernel_vaddr,
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unsigned long decrypted_kernel_vaddr,
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unsigned long kernel_len,
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unsigned long encryption_wa,
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unsigned long encryption_pgd);
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void __init sme_early_encrypt(resource_size_t paddr,
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void __init sme_early_encrypt(resource_size_t paddr,
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unsigned long size);
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unsigned long size);
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void __init sme_early_decrypt(resource_size_t paddr,
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void __init sme_early_decrypt(resource_size_t paddr,
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@ -40,3 +40,4 @@ obj-$(CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS) += pkeys.o
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obj-$(CONFIG_RANDOMIZE_MEMORY) += kaslr.o
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obj-$(CONFIG_RANDOMIZE_MEMORY) += kaslr.o
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obj-$(CONFIG_AMD_MEM_ENCRYPT) += mem_encrypt.o
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obj-$(CONFIG_AMD_MEM_ENCRYPT) += mem_encrypt.o
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obj-$(CONFIG_AMD_MEM_ENCRYPT) += mem_encrypt_boot.o
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@ -21,6 +21,8 @@
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#include <asm/setup.h>
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#include <asm/setup.h>
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#include <asm/bootparam.h>
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#include <asm/bootparam.h>
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#include <asm/set_memory.h>
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#include <asm/set_memory.h>
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#include <asm/cacheflush.h>
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#include <asm/sections.h>
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/*
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/*
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* Since SME related variables are set early in the boot process they must
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* Since SME related variables are set early in the boot process they must
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@ -199,8 +201,316 @@ void swiotlb_set_mem_attributes(void *vaddr, unsigned long size)
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set_memory_decrypted((unsigned long)vaddr, size >> PAGE_SHIFT);
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set_memory_decrypted((unsigned long)vaddr, size >> PAGE_SHIFT);
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}
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}
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static void __init sme_clear_pgd(pgd_t *pgd_base, unsigned long start,
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unsigned long end)
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{
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unsigned long pgd_start, pgd_end, pgd_size;
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pgd_t *pgd_p;
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pgd_start = start & PGDIR_MASK;
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pgd_end = end & PGDIR_MASK;
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pgd_size = (((pgd_end - pgd_start) / PGDIR_SIZE) + 1);
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pgd_size *= sizeof(pgd_t);
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pgd_p = pgd_base + pgd_index(start);
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memset(pgd_p, 0, pgd_size);
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}
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#define PGD_FLAGS _KERNPG_TABLE_NOENC
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#define P4D_FLAGS _KERNPG_TABLE_NOENC
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#define PUD_FLAGS _KERNPG_TABLE_NOENC
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#define PMD_FLAGS (__PAGE_KERNEL_LARGE_EXEC & ~_PAGE_GLOBAL)
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static void __init *sme_populate_pgd(pgd_t *pgd_base, void *pgtable_area,
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unsigned long vaddr, pmdval_t pmd_val)
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{
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pgd_t *pgd_p;
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p4d_t *p4d_p;
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pud_t *pud_p;
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pmd_t *pmd_p;
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pgd_p = pgd_base + pgd_index(vaddr);
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if (native_pgd_val(*pgd_p)) {
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if (IS_ENABLED(CONFIG_X86_5LEVEL))
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p4d_p = (p4d_t *)(native_pgd_val(*pgd_p) & ~PTE_FLAGS_MASK);
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else
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pud_p = (pud_t *)(native_pgd_val(*pgd_p) & ~PTE_FLAGS_MASK);
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} else {
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pgd_t pgd;
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if (IS_ENABLED(CONFIG_X86_5LEVEL)) {
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p4d_p = pgtable_area;
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memset(p4d_p, 0, sizeof(*p4d_p) * PTRS_PER_P4D);
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pgtable_area += sizeof(*p4d_p) * PTRS_PER_P4D;
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pgd = native_make_pgd((pgdval_t)p4d_p + PGD_FLAGS);
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} else {
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pud_p = pgtable_area;
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memset(pud_p, 0, sizeof(*pud_p) * PTRS_PER_PUD);
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pgtable_area += sizeof(*pud_p) * PTRS_PER_PUD;
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pgd = native_make_pgd((pgdval_t)pud_p + PGD_FLAGS);
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}
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native_set_pgd(pgd_p, pgd);
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}
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if (IS_ENABLED(CONFIG_X86_5LEVEL)) {
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p4d_p += p4d_index(vaddr);
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if (native_p4d_val(*p4d_p)) {
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pud_p = (pud_t *)(native_p4d_val(*p4d_p) & ~PTE_FLAGS_MASK);
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} else {
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p4d_t p4d;
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pud_p = pgtable_area;
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memset(pud_p, 0, sizeof(*pud_p) * PTRS_PER_PUD);
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pgtable_area += sizeof(*pud_p) * PTRS_PER_PUD;
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p4d = native_make_p4d((pudval_t)pud_p + P4D_FLAGS);
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native_set_p4d(p4d_p, p4d);
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}
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}
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pud_p += pud_index(vaddr);
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if (native_pud_val(*pud_p)) {
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if (native_pud_val(*pud_p) & _PAGE_PSE)
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goto out;
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pmd_p = (pmd_t *)(native_pud_val(*pud_p) & ~PTE_FLAGS_MASK);
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} else {
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pud_t pud;
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pmd_p = pgtable_area;
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memset(pmd_p, 0, sizeof(*pmd_p) * PTRS_PER_PMD);
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pgtable_area += sizeof(*pmd_p) * PTRS_PER_PMD;
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pud = native_make_pud((pmdval_t)pmd_p + PUD_FLAGS);
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native_set_pud(pud_p, pud);
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}
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pmd_p += pmd_index(vaddr);
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if (!native_pmd_val(*pmd_p) || !(native_pmd_val(*pmd_p) & _PAGE_PSE))
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native_set_pmd(pmd_p, native_make_pmd(pmd_val));
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out:
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return pgtable_area;
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}
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static unsigned long __init sme_pgtable_calc(unsigned long len)
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{
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unsigned long p4d_size, pud_size, pmd_size;
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unsigned long total;
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/*
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* Perform a relatively simplistic calculation of the pagetable
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* entries that are needed. That mappings will be covered by 2MB
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* PMD entries so we can conservatively calculate the required
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* number of P4D, PUD and PMD structures needed to perform the
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* mappings. Incrementing the count for each covers the case where
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* the addresses cross entries.
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*/
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if (IS_ENABLED(CONFIG_X86_5LEVEL)) {
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p4d_size = (ALIGN(len, PGDIR_SIZE) / PGDIR_SIZE) + 1;
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p4d_size *= sizeof(p4d_t) * PTRS_PER_P4D;
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pud_size = (ALIGN(len, P4D_SIZE) / P4D_SIZE) + 1;
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pud_size *= sizeof(pud_t) * PTRS_PER_PUD;
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} else {
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p4d_size = 0;
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pud_size = (ALIGN(len, PGDIR_SIZE) / PGDIR_SIZE) + 1;
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pud_size *= sizeof(pud_t) * PTRS_PER_PUD;
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}
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pmd_size = (ALIGN(len, PUD_SIZE) / PUD_SIZE) + 1;
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pmd_size *= sizeof(pmd_t) * PTRS_PER_PMD;
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total = p4d_size + pud_size + pmd_size;
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/*
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* Now calculate the added pagetable structures needed to populate
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* the new pagetables.
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*/
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if (IS_ENABLED(CONFIG_X86_5LEVEL)) {
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p4d_size = ALIGN(total, PGDIR_SIZE) / PGDIR_SIZE;
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p4d_size *= sizeof(p4d_t) * PTRS_PER_P4D;
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pud_size = ALIGN(total, P4D_SIZE) / P4D_SIZE;
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pud_size *= sizeof(pud_t) * PTRS_PER_PUD;
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} else {
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p4d_size = 0;
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pud_size = ALIGN(total, PGDIR_SIZE) / PGDIR_SIZE;
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pud_size *= sizeof(pud_t) * PTRS_PER_PUD;
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}
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pmd_size = ALIGN(total, PUD_SIZE) / PUD_SIZE;
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pmd_size *= sizeof(pmd_t) * PTRS_PER_PMD;
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total += p4d_size + pud_size + pmd_size;
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return total;
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}
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void __init sme_encrypt_kernel(void)
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void __init sme_encrypt_kernel(void)
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{
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{
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unsigned long workarea_start, workarea_end, workarea_len;
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unsigned long execute_start, execute_end, execute_len;
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unsigned long kernel_start, kernel_end, kernel_len;
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unsigned long pgtable_area_len;
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unsigned long paddr, pmd_flags;
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unsigned long decrypted_base;
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void *pgtable_area;
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pgd_t *pgd;
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if (!sme_active())
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return;
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/*
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* Prepare for encrypting the kernel by building new pagetables with
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* the necessary attributes needed to encrypt the kernel in place.
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*
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* One range of virtual addresses will map the memory occupied
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* by the kernel as encrypted.
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*
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* Another range of virtual addresses will map the memory occupied
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* by the kernel as decrypted and write-protected.
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*
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* The use of write-protect attribute will prevent any of the
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* memory from being cached.
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*/
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/* Physical addresses gives us the identity mapped virtual addresses */
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kernel_start = __pa_symbol(_text);
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kernel_end = ALIGN(__pa_symbol(_end), PMD_PAGE_SIZE);
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kernel_len = kernel_end - kernel_start;
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/* Set the encryption workarea to be immediately after the kernel */
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workarea_start = kernel_end;
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/*
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* Calculate required number of workarea bytes needed:
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* executable encryption area size:
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* stack page (PAGE_SIZE)
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* encryption routine page (PAGE_SIZE)
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* intermediate copy buffer (PMD_PAGE_SIZE)
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* pagetable structures for the encryption of the kernel
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* pagetable structures for workarea (in case not currently mapped)
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*/
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execute_start = workarea_start;
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execute_end = execute_start + (PAGE_SIZE * 2) + PMD_PAGE_SIZE;
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execute_len = execute_end - execute_start;
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/*
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* One PGD for both encrypted and decrypted mappings and a set of
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* PUDs and PMDs for each of the encrypted and decrypted mappings.
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*/
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pgtable_area_len = sizeof(pgd_t) * PTRS_PER_PGD;
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pgtable_area_len += sme_pgtable_calc(execute_end - kernel_start) * 2;
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/* PUDs and PMDs needed in the current pagetables for the workarea */
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pgtable_area_len += sme_pgtable_calc(execute_len + pgtable_area_len);
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/*
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* The total workarea includes the executable encryption area and
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* the pagetable area.
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*/
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workarea_len = execute_len + pgtable_area_len;
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workarea_end = workarea_start + workarea_len;
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/*
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* Set the address to the start of where newly created pagetable
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* structures (PGDs, PUDs and PMDs) will be allocated. New pagetable
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* structures are created when the workarea is added to the current
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* pagetables and when the new encrypted and decrypted kernel
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* mappings are populated.
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*/
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pgtable_area = (void *)execute_end;
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/*
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* Make sure the current pagetable structure has entries for
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* addressing the workarea.
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*/
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pgd = (pgd_t *)native_read_cr3_pa();
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paddr = workarea_start;
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while (paddr < workarea_end) {
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pgtable_area = sme_populate_pgd(pgd, pgtable_area,
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paddr,
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paddr + PMD_FLAGS);
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paddr += PMD_PAGE_SIZE;
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}
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/* Flush the TLB - no globals so cr3 is enough */
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native_write_cr3(__native_read_cr3());
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/*
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* A new pagetable structure is being built to allow for the kernel
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* to be encrypted. It starts with an empty PGD that will then be
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* populated with new PUDs and PMDs as the encrypted and decrypted
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* kernel mappings are created.
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*/
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pgd = pgtable_area;
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memset(pgd, 0, sizeof(*pgd) * PTRS_PER_PGD);
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pgtable_area += sizeof(*pgd) * PTRS_PER_PGD;
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/* Add encrypted kernel (identity) mappings */
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pmd_flags = PMD_FLAGS | _PAGE_ENC;
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paddr = kernel_start;
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while (paddr < kernel_end) {
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pgtable_area = sme_populate_pgd(pgd, pgtable_area,
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paddr,
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paddr + pmd_flags);
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paddr += PMD_PAGE_SIZE;
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}
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/*
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* A different PGD index/entry must be used to get different
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* pagetable entries for the decrypted mapping. Choose the next
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* PGD index and convert it to a virtual address to be used as
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* the base of the mapping.
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*/
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decrypted_base = (pgd_index(workarea_end) + 1) & (PTRS_PER_PGD - 1);
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decrypted_base <<= PGDIR_SHIFT;
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/* Add decrypted, write-protected kernel (non-identity) mappings */
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pmd_flags = (PMD_FLAGS & ~_PAGE_CACHE_MASK) | (_PAGE_PAT | _PAGE_PWT);
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paddr = kernel_start;
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while (paddr < kernel_end) {
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pgtable_area = sme_populate_pgd(pgd, pgtable_area,
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paddr + decrypted_base,
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paddr + pmd_flags);
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paddr += PMD_PAGE_SIZE;
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}
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/* Add decrypted workarea mappings to both kernel mappings */
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paddr = workarea_start;
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while (paddr < workarea_end) {
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pgtable_area = sme_populate_pgd(pgd, pgtable_area,
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||||||
|
paddr,
|
||||||
|
paddr + PMD_FLAGS);
|
||||||
|
|
||||||
|
pgtable_area = sme_populate_pgd(pgd, pgtable_area,
|
||||||
|
paddr + decrypted_base,
|
||||||
|
paddr + PMD_FLAGS);
|
||||||
|
|
||||||
|
paddr += PMD_PAGE_SIZE;
|
||||||
|
}
|
||||||
|
|
||||||
|
/* Perform the encryption */
|
||||||
|
sme_encrypt_execute(kernel_start, kernel_start + decrypted_base,
|
||||||
|
kernel_len, workarea_start, (unsigned long)pgd);
|
||||||
|
|
||||||
|
/*
|
||||||
|
* At this point we are running encrypted. Remove the mappings for
|
||||||
|
* the decrypted areas - all that is needed for this is to remove
|
||||||
|
* the PGD entry/entries.
|
||||||
|
*/
|
||||||
|
sme_clear_pgd(pgd, kernel_start + decrypted_base,
|
||||||
|
kernel_end + decrypted_base);
|
||||||
|
|
||||||
|
sme_clear_pgd(pgd, workarea_start + decrypted_base,
|
||||||
|
workarea_end + decrypted_base);
|
||||||
|
|
||||||
|
/* Flush the TLB - no globals so cr3 is enough */
|
||||||
|
native_write_cr3(__native_read_cr3());
|
||||||
}
|
}
|
||||||
|
|
||||||
void __init sme_enable(void)
|
void __init sme_enable(void)
|
||||||
|
|
|
||||||
149
arch/x86/mm/mem_encrypt_boot.S
Normal file
149
arch/x86/mm/mem_encrypt_boot.S
Normal file
|
|
@ -0,0 +1,149 @@
|
||||||
|
/*
|
||||||
|
* AMD Memory Encryption Support
|
||||||
|
*
|
||||||
|
* Copyright (C) 2016 Advanced Micro Devices, Inc.
|
||||||
|
*
|
||||||
|
* Author: Tom Lendacky <thomas.lendacky@amd.com>
|
||||||
|
*
|
||||||
|
* This program is free software; you can redistribute it and/or modify
|
||||||
|
* it under the terms of the GNU General Public License version 2 as
|
||||||
|
* published by the Free Software Foundation.
|
||||||
|
*/
|
||||||
|
|
||||||
|
#include <linux/linkage.h>
|
||||||
|
#include <asm/pgtable.h>
|
||||||
|
#include <asm/page.h>
|
||||||
|
#include <asm/processor-flags.h>
|
||||||
|
#include <asm/msr-index.h>
|
||||||
|
#include <asm/frame.h>
|
||||||
|
|
||||||
|
.text
|
||||||
|
.code64
|
||||||
|
ENTRY(sme_encrypt_execute)
|
||||||
|
|
||||||
|
/*
|
||||||
|
* Entry parameters:
|
||||||
|
* RDI - virtual address for the encrypted kernel mapping
|
||||||
|
* RSI - virtual address for the decrypted kernel mapping
|
||||||
|
* RDX - length of kernel
|
||||||
|
* RCX - virtual address of the encryption workarea, including:
|
||||||
|
* - stack page (PAGE_SIZE)
|
||||||
|
* - encryption routine page (PAGE_SIZE)
|
||||||
|
* - intermediate copy buffer (PMD_PAGE_SIZE)
|
||||||
|
* R8 - physcial address of the pagetables to use for encryption
|
||||||
|
*/
|
||||||
|
|
||||||
|
FRAME_BEGIN /* RBP now has original stack pointer */
|
||||||
|
|
||||||
|
/* Set up a one page stack in the non-encrypted memory area */
|
||||||
|
movq %rcx, %rax /* Workarea stack page */
|
||||||
|
leaq PAGE_SIZE(%rax), %rsp /* Set new stack pointer */
|
||||||
|
addq $PAGE_SIZE, %rax /* Workarea encryption routine */
|
||||||
|
|
||||||
|
push %r12
|
||||||
|
movq %rdi, %r10 /* Encrypted kernel */
|
||||||
|
movq %rsi, %r11 /* Decrypted kernel */
|
||||||
|
movq %rdx, %r12 /* Kernel length */
|
||||||
|
|
||||||
|
/* Copy encryption routine into the workarea */
|
||||||
|
movq %rax, %rdi /* Workarea encryption routine */
|
||||||
|
leaq __enc_copy(%rip), %rsi /* Encryption routine */
|
||||||
|
movq $(.L__enc_copy_end - __enc_copy), %rcx /* Encryption routine length */
|
||||||
|
rep movsb
|
||||||
|
|
||||||
|
/* Setup registers for call */
|
||||||
|
movq %r10, %rdi /* Encrypted kernel */
|
||||||
|
movq %r11, %rsi /* Decrypted kernel */
|
||||||
|
movq %r8, %rdx /* Pagetables used for encryption */
|
||||||
|
movq %r12, %rcx /* Kernel length */
|
||||||
|
movq %rax, %r8 /* Workarea encryption routine */
|
||||||
|
addq $PAGE_SIZE, %r8 /* Workarea intermediate copy buffer */
|
||||||
|
|
||||||
|
call *%rax /* Call the encryption routine */
|
||||||
|
|
||||||
|
pop %r12
|
||||||
|
|
||||||
|
movq %rbp, %rsp /* Restore original stack pointer */
|
||||||
|
FRAME_END
|
||||||
|
|
||||||
|
ret
|
||||||
|
ENDPROC(sme_encrypt_execute)
|
||||||
|
|
||||||
|
ENTRY(__enc_copy)
|
||||||
|
/*
|
||||||
|
* Routine used to encrypt kernel.
|
||||||
|
* This routine must be run outside of the kernel proper since
|
||||||
|
* the kernel will be encrypted during the process. So this
|
||||||
|
* routine is defined here and then copied to an area outside
|
||||||
|
* of the kernel where it will remain and run decrypted
|
||||||
|
* during execution.
|
||||||
|
*
|
||||||
|
* On entry the registers must be:
|
||||||
|
* RDI - virtual address for the encrypted kernel mapping
|
||||||
|
* RSI - virtual address for the decrypted kernel mapping
|
||||||
|
* RDX - address of the pagetables to use for encryption
|
||||||
|
* RCX - length of kernel
|
||||||
|
* R8 - intermediate copy buffer
|
||||||
|
*
|
||||||
|
* RAX - points to this routine
|
||||||
|
*
|
||||||
|
* The kernel will be encrypted by copying from the non-encrypted
|
||||||
|
* kernel space to an intermediate buffer and then copying from the
|
||||||
|
* intermediate buffer back to the encrypted kernel space. The physical
|
||||||
|
* addresses of the two kernel space mappings are the same which
|
||||||
|
* results in the kernel being encrypted "in place".
|
||||||
|
*/
|
||||||
|
/* Enable the new page tables */
|
||||||
|
mov %rdx, %cr3
|
||||||
|
|
||||||
|
/* Flush any global TLBs */
|
||||||
|
mov %cr4, %rdx
|
||||||
|
andq $~X86_CR4_PGE, %rdx
|
||||||
|
mov %rdx, %cr4
|
||||||
|
orq $X86_CR4_PGE, %rdx
|
||||||
|
mov %rdx, %cr4
|
||||||
|
|
||||||
|
/* Set the PAT register PA5 entry to write-protect */
|
||||||
|
push %rcx
|
||||||
|
movl $MSR_IA32_CR_PAT, %ecx
|
||||||
|
rdmsr
|
||||||
|
push %rdx /* Save original PAT value */
|
||||||
|
andl $0xffff00ff, %edx /* Clear PA5 */
|
||||||
|
orl $0x00000500, %edx /* Set PA5 to WP */
|
||||||
|
wrmsr
|
||||||
|
pop %rdx /* RDX contains original PAT value */
|
||||||
|
pop %rcx
|
||||||
|
|
||||||
|
movq %rcx, %r9 /* Save kernel length */
|
||||||
|
movq %rdi, %r10 /* Save encrypted kernel address */
|
||||||
|
movq %rsi, %r11 /* Save decrypted kernel address */
|
||||||
|
|
||||||
|
wbinvd /* Invalidate any cache entries */
|
||||||
|
|
||||||
|
/* Copy/encrypt 2MB at a time */
|
||||||
|
1:
|
||||||
|
movq %r11, %rsi /* Source - decrypted kernel */
|
||||||
|
movq %r8, %rdi /* Dest - intermediate copy buffer */
|
||||||
|
movq $PMD_PAGE_SIZE, %rcx /* 2MB length */
|
||||||
|
rep movsb
|
||||||
|
|
||||||
|
movq %r8, %rsi /* Source - intermediate copy buffer */
|
||||||
|
movq %r10, %rdi /* Dest - encrypted kernel */
|
||||||
|
movq $PMD_PAGE_SIZE, %rcx /* 2MB length */
|
||||||
|
rep movsb
|
||||||
|
|
||||||
|
addq $PMD_PAGE_SIZE, %r11
|
||||||
|
addq $PMD_PAGE_SIZE, %r10
|
||||||
|
subq $PMD_PAGE_SIZE, %r9 /* Kernel length decrement */
|
||||||
|
jnz 1b /* Kernel length not zero? */
|
||||||
|
|
||||||
|
/* Restore PAT register */
|
||||||
|
push %rdx /* Save original PAT value */
|
||||||
|
movl $MSR_IA32_CR_PAT, %ecx
|
||||||
|
rdmsr
|
||||||
|
pop %rdx /* Restore original PAT value */
|
||||||
|
wrmsr
|
||||||
|
|
||||||
|
ret
|
||||||
|
.L__enc_copy_end:
|
||||||
|
ENDPROC(__enc_copy)
|
||||||
Loading…
Reference in a new issue