diff options
| author | Arthur Heymans <arthur@aheymans.xyz> | 2018-06-16 20:01:47 +0200 |
|---|---|---|
| committer | Kyösti Mälkki <kyosti.malkki@gmail.com> | 2018-06-27 11:48:53 +0000 |
| commit | 7875dbd9812e2359de2c5aed7754703138878466 (patch) | |
| tree | 9b49b722d780bd2707e4764b6a85239e5cd916de /src/cpu | |
| parent | ce9f422b512c376ba0eeec41db92d9a87155105a (diff) | |
cpu/intel/p4-netburst: skip caching rom on model_fxx
An unidentified combination of speculative reads and branch
predictions inside WRPROT-cacheable memory can cause invalidation of
cachelines and loss of stack on models based on NetBurst
microarchitecture.
Therefore disable WRPROT region entirely for all family F models.
As an extreme example, just changing the location of a constant string
passed to printk() has been witnessed to make a the boot fail early on
in romstage.
Change-Id: I1df84ad55e2d8d6d4e8dca10125131b5f525f0d7
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/27133
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Diffstat (limited to 'src/cpu')
| -rw-r--r-- | src/cpu/intel/car/p4-netburst/cache_as_ram.S | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/src/cpu/intel/car/p4-netburst/cache_as_ram.S b/src/cpu/intel/car/p4-netburst/cache_as_ram.S index 63ee7236ea..95ecba96bd 100644 --- a/src/cpu/intel/car/p4-netburst/cache_as_ram.S +++ b/src/cpu/intel/car/p4-netburst/cache_as_ram.S @@ -315,6 +315,18 @@ no_msr_11e: orl $CR0_CacheDisable, %eax movl %eax, %cr0 + /* + * An unidentified combination of speculative reads and branch + * predictions inside WRPROT-cacheable memory can cause invalidation + * of cachelines and loss of stack on models based on NetBurst + * microarchitecture. Therefore disable WRPROT region entirely for + * all family F models. + */ + movl $1, %eax + cpuid + cmp $0xf, %ah + je skip_cache_rom + /* Enable cache for our code in Flash because we do XIP here */ movl $MTRR_PHYS_BASE(1), %ecx xorl %edx, %edx @@ -332,6 +344,8 @@ no_msr_11e: movl $(~(CONFIG_XIP_ROM_SIZE - 1) | MTRR_PHYS_MASK_VALID), %eax wrmsr +skip_cache_rom: + post_code(0x2e) /* Enable cache. */ movl %cr0, %eax |