diff options
Diffstat (limited to 'src/security/intel/txt/getsec_sclean.S')
| -rw-r--r-- | src/security/intel/txt/getsec_sclean.S | 181 |
1 files changed, 181 insertions, 0 deletions
diff --git a/src/security/intel/txt/getsec_sclean.S b/src/security/intel/txt/getsec_sclean.S new file mode 100644 index 000000000000..e240a2faaa36 --- /dev/null +++ b/src/security/intel/txt/getsec_sclean.S @@ -0,0 +1,181 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ + +#include <cpu/x86/cr.h> +#include <cpu/x86/mtrr.h> +#include <cpu/x86/msr.h> + +#include "getsec_mtrr_setup.inc" + +#define MTRR_HIGH_MASK $((1 << (CONFIG_CPU_ADDR_BITS - 32)) - 1) + +#define NO_EVICT_MODE 0x2e0 + +.align 4 +.text + +/* + * void getsec_sclean(const uint32_t acm_base, const uint32_t acm_size); + */ +.global getsec_sclean +getsec_sclean: + /* + * At this point, it is certain that the BIOS ACM will be run. + * This requires tearing down CAR, which cannot be undone. + * + * From here onwards, the only way out is to reset the system. + */ + + /* Enable SMXE, SSE and debug extensions */ + movl %cr4, %eax + orl $(CR4_OSFXSR | CR4_DE | CR4_SMXE), %eax + movl %eax, %cr4 + + /* + * Save arguments into SSE registers. We need to tear down CAR + * before launching the BIOS ACM, which will destroy the stack. + */ + movd 4(%esp), %xmm2 /* acm_base */ + movd 8(%esp), %xmm3 /* acm_size */ + + /* Disable cache */ + movl %cr0, %eax + orl $(CR0_CD | CR0_NE), %eax + andl $(~(CR0_NW)), %eax + movl %eax, %cr0 + + /* Invalidate the cache */ + invd + + /* Disable MTRRs */ + movl $(MTRR_DEF_TYPE_MSR), %ecx + xorl %eax, %eax + xorl %edx, %edx + wrmsr + + /* Disable NEM, needs to be done in two steps */ + movl $NO_EVICT_MODE, %ecx + rdmsr + andl $~2, %eax /* Clear NEM Run bit */ + wrmsr + andl $~1, %eax /* Clear NEM Setup bit */ + wrmsr + + /* Invalidate the cache, again */ + invd + + /* + * Clear variable MTRRs + * Chapter 2.2.5.1 + * Intel TXT Software Development Guide (Document: 315168-015) + */ + movl $(MTRR_CAP_MSR), %ecx + rdmsr + andl $(0xff), %eax + movl %eax, %ebx + + xorl %eax, %eax + xorl %edx, %edx + + jmp cond_clear_var_mtrrs + +body_clear_var_mtrrs: + + decl %ebx + movl %ebx, %ecx + shll %ecx + addl $(MTRR_PHYS_BASE(0)), %ecx + wrmsr + incl %ecx /* MTRR_PHYS_MASK */ + wrmsr + +cond_clear_var_mtrrs: + + cmpl $0, %ebx + jnz body_clear_var_mtrrs + + /* + * Setup BIOS ACM as WB + * Chapter A.1.1 + * Intel TXT Software Development Guide (Document: 315168-015) + */ + + /* Determine size of AC module */ + movd %xmm2, %eax /* acm_base */ + movd %xmm3, %ebx /* acm_size */ + + /* Round up to page size */ + addl $(0xfff), %ebx + andl $(~0xfff), %ebx /* Aligned to a page (4 KiB) */ + + /* Use SSE registers to store local variables */ + movd %eax, %xmm0 + movd %ebx, %xmm1 + + /* + * Important note: The MTRRs must cache less than a page (4 KiB) + * of unused memory after the BIOS ACM. Not doing so on Haswell + * will cause a TXT reset with Class Code 5, Major Error Code 2. + * + * The caller must have checked that there are enough variable + * MTRRs to cache the ACM size prior to invoking this routine. + */ + SET_UP_MTRRS_FOR_BIOS_ACM + + /* Enable variable MTRRs */ + movl $MTRR_DEF_TYPE_MSR, %ecx + rdmsr + orl $MTRR_DEF_TYPE_EN, %eax + wrmsr + + /* Enable cache - CR0_NW is and stays clear */ + movl %cr0, %eax + andl $~(CR0_CD), %eax + movl %eax, %cr0 + + /* + * Get function arguments. + * It's important to pass the exact ACM size as it's used by getsec to verify + * the integrity of ACM. Unlike the size for MTRR programming, which needs to + * be power of two. + * + * Note: Do not forget that CAR has been torn down, so the stack doesn't exist. + */ + movl $2, %eax /* GETSEC[ENTERACCS] */ + movd %xmm2, %ebx /* acm_base */ + movd %xmm3, %ecx /* acm_size */ + movl $0, %edx /* reserved, must be zero */ + movl $0, %edi /* must be zero */ + movl $0, %esi /* SCLEAN */ + + getsec + + /* + * The platform state after SCLEAN is undefined. The only sane + * thing to do afterwards is to reset the platform. Note that + * the BIOS ACM should already reset the platform, so this code + * may not always be reached, but keep it here just to be sure. + */ +#if 1 + movw $0xcf8, %dx + movl $0x8000F8AC, %eax + outl %eax, %dx + + movw $0xcfc, %dx + inl %dx, %eax + andl $~(1 << 20), %eax + outl %eax, %dx +#endif + + movw $0xcf9, %dx + movb $0, %al + outb %al, %dx + + movw $0xcf9, %dx + movb $0x0e, %al + outb %al, %dx + + cli + + hlt + + ret |