Messages in this thread Patch in this message | | | From | Bryan O'Donoghue <> | Subject | [PATCH 3/3] x86: Quark: Comment setup_arch for TLB/PGE bugfix | Date | Tue, 30 Sep 2014 04:11:50 +0100 |
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Quark X1000 requires CR3 to be rewritten to flush TLB entries irrespective of the PGE bits in CR4 or PTE.PGE
Add a comment to setup_arch to indicate that the code
load_cr3(swapper_pg_dir); __flush_tlb_all();
Will already have flushed the TLB @ the CR3 reload allowing us to skip over a potential if/else for Quark.
This comment clearly states the bug, the behaviour we rely on and the reason why we only do it this way - one time.
Later on cpu_has_pge() will be false due to a fixup in intel_init_early() and __flush_tlb_all() will work as expected from that point onwards
Signed-off-by: Bryan O'Donoghue <pure.logic@nexus-software.ie> --- arch/x86/kernel/setup.c | 12 ++++++++++++ 1 file changed, 12 insertions(+)
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c index 41ead8d..98b6660 100644 --- a/arch/x86/kernel/setup.c +++ b/arch/x86/kernel/setup.c @@ -878,6 +878,18 @@ void __init setup_arch(char **cmdline_p) initial_page_table + KERNEL_PGD_BOUNDARY, KERNEL_PGD_PTRS); + /* + * Locate the page directory and flush the TLB. + * + * On Quark X1000 CPUs we still have the PGE bit incorrectly set + * due to a processor erratum, so __flush_tlb_all() is not yet + * doing what it says. Fortunately we have a cr3 load here, + * which is what is needed on this processor to flush TLBs, so + * there's no need to add a Quark X1000 quirk here. + * + * early_init_intel will unset the X86_FEATURE_PGE flag later + * and __flush_tlb_all() will flush via cr3 + */ load_cr3(swapper_pg_dir); __flush_tlb_all(); #else -- 1.9.1
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