diff options
author | Jonathan Corbet <corbet@lwn.net> | 2019-10-29 04:43:29 -0600 |
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committer | Jonathan Corbet <corbet@lwn.net> | 2019-10-29 04:43:29 -0600 |
commit | 822bbba0cabb50825a0ce22707dc45eb82d02853 (patch) | |
tree | ea61d4ca72cb60b4cae8e95f64eefa7cd2a36603 /arch/x86/kernel/head64.c | |
parent | d41abfd7ae33cd3c1d9189438937d61cb75e690a (diff) | |
parent | 7d194c2100ad2a6dded545887d02754948ca5241 (diff) |
Merge tag 'v5.4-rc4' into docs-next
I need to pick up the independent changes made to
Documentation/core-api/memory-allocation.rst to be able to merge further
work without creating a total mess.
Diffstat (limited to 'arch/x86/kernel/head64.c')
-rw-r--r-- | arch/x86/kernel/head64.c | 22 |
1 files changed, 20 insertions, 2 deletions
diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c index 29ffa495bd1c..206a4b6144c2 100644 --- a/arch/x86/kernel/head64.c +++ b/arch/x86/kernel/head64.c @@ -222,13 +222,31 @@ unsigned long __head __startup_64(unsigned long physaddr, * we might write invalid pmds, when the kernel is relocated * cleanup_highmap() fixes this up along with the mappings * beyond _end. + * + * Only the region occupied by the kernel image has so far + * been checked against the table of usable memory regions + * provided by the firmware, so invalidate pages outside that + * region. A page table entry that maps to a reserved area of + * memory would allow processor speculation into that area, + * and on some hardware (particularly the UV platform) even + * speculative access to some reserved areas is caught as an + * error, causing the BIOS to halt the system. */ pmd = fixup_pointer(level2_kernel_pgt, physaddr); - for (i = 0; i < PTRS_PER_PMD; i++) { + + /* invalidate pages before the kernel image */ + for (i = 0; i < pmd_index((unsigned long)_text); i++) + pmd[i] &= ~_PAGE_PRESENT; + + /* fixup pages that are part of the kernel image */ + for (; i <= pmd_index((unsigned long)_end); i++) if (pmd[i] & _PAGE_PRESENT) pmd[i] += load_delta; - } + + /* invalidate pages after the kernel image */ + for (; i < PTRS_PER_PMD; i++) + pmd[i] &= ~_PAGE_PRESENT; /* * Fixup phys_base - remove the memory encryption mask to obtain |