diff options
| author | Angel Pons <th3fanbus@gmail.com> | 2020-08-04 19:22:01 +0200 |
|---|---|---|
| committer | Angel Pons <th3fanbus@gmail.com> | 2020-08-07 11:56:29 +0000 |
| commit | 2f1739ada8a32a70dbd5a3fd1a3d6fd5fba6d291 (patch) | |
| tree | 9dffa1ffb9d10b34600344fddca6cfba19d8c0d2 | |
| parent | bf9bc50ec1d1b54a9ae0b86fc1e37e013422186f (diff) | |
security/intel/txt: Fix variable MTRR handling
The MSR macros were treated as memory addresses and the loops had
off-by-one errors. This resulted in a CPU exception before GETSEC, and
another exception after GETSEC (once the first exception was fixed).
Tested on Asrock B85M Pro4, ACM complains about the missing TPM and
resets the platform. When the `getsec` instruction is commented-out, the
board is able to boot normally, without any exceptions nor corruption.
Change-Id: Ib5d23cf9885401f3ec69b0f14cea7bad77eee19a
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/44183
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Philipp Deppenwiese <zaolin.daisuki@gmail.com>
| -rw-r--r-- | src/security/intel/txt/getsec_enteraccs.S | 95 |
1 files changed, 47 insertions, 48 deletions
diff --git a/src/security/intel/txt/getsec_enteraccs.S b/src/security/intel/txt/getsec_enteraccs.S index 0dd5237e7a..3135de79b2 100644 --- a/src/security/intel/txt/getsec_enteraccs.S +++ b/src/security/intel/txt/getsec_enteraccs.S @@ -27,46 +27,6 @@ wrmsr .endm -/* Variable MTRR index is passed through %ebx */ -.macro PUSH_VAR_MTRR - movl %ebx, %ecx - shll %ecx - addl MTRR_PHYS_BASE(0), %ecx - rdmsr - push %eax - push %edx - incl %ecx /* MTRR_PHYS_MASK */ - rdmsr - push %eax - push %edx -.endm - -.macro POP_VAR_MTRR - movl %ebx, %ecx - shll %ecx - addl MTRR_PHYS_MASK(0), %ecx - pop %edx - pop %eax - wrmsr - decl %ecx /* MTRR_PHYS_BASE */ - pop %edx - pop %eax - wrmsr -.endm - -.macro CLEAR_VAR_MTRR - movl %ebx, %ecx - shll %ecx - addl MTRR_PHYS_BASE(0), %ecx - xorl %edx, %edx - xorl %eax, %eax - wrmsr - incl %ecx /* MTRR_PHYS_MASK */ - xorl %edx, %edx - xorl %eax, %eax - wrmsr -.endm - .align 4 .text @@ -111,12 +71,23 @@ getsec_enteraccs: PUSH_MSR MTRR_FIX_4K_F8000 /* Push variable MTRRs in ascending order */ + xorl %ebx, %ebx jmp cond_push_var_mtrrs body_push_var_mtrrs: - PUSH_VAR_MTRR + movl %ebx, %ecx + shll %ecx + addl $(MTRR_PHYS_BASE(0)), %ecx + rdmsr + push %eax + push %edx + incl %ecx /* MTRR_PHYS_MASK */ + rdmsr + push %eax + push %edx + incl %ebx cond_push_var_mtrrs: @@ -125,7 +96,7 @@ cond_push_var_mtrrs: rdmsr andl $(0xff), %eax cmp %ebx, %eax - jge body_push_var_mtrrs + jg body_push_var_mtrrs /* * Disable cache. @@ -168,10 +139,24 @@ cond_push_var_mtrrs: andl $(0xff), %eax movl %eax, %ebx + xorl %eax, %eax + xorl %edx, %edx + + jmp cond_clear_var_mtrrs + body_clear_var_mtrrs: - CLEAR_VAR_MTRR 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 /* @@ -266,19 +251,33 @@ body_clear_var_mtrrs: orl $(CR0_CD | CR0_NW), %eax movl %eax, %cr0 - /* Restore MTTRs */ - /* Pop variable MTRRs in descending order */ + movl $(MTRR_CAP_MSR), %ecx rdmsr andl $(0xff), %eax movl %eax, %ebx + jmp cond_pop_var_mtrrs + body_pop_var_mtrrs: - POP_VAR_MTRR decl %ebx - jnz body_pop_var_mtrrs + movl %ebx, %ecx + shll %ecx + addl $(MTRR_PHYS_MASK(0)), %ecx + pop %edx + pop %eax + wrmsr + decl %ecx /* MTRR_PHYS_BASE */ + pop %edx + pop %eax + wrmsr + +cond_pop_var_mtrrs: + + cmpl $0, %ebx + jne body_pop_var_mtrrs POP_MSR MTRR_FIX_4K_F8000 POP_MSR MTRR_FIX_4K_F0000 @@ -301,7 +300,7 @@ body_pop_var_mtrrs: /* Enable cache */ movl %cr0, %eax andl $(~(CR0_CD | CR0_NW)), %eax - movl %eax, %cr0 + movl %eax, %cr0 /* Pop GDT */ addl $8, %esp |