Hi all, On Mon, 25 May 2020 21:04:43 +1000 Stephen Rothwell <[email protected]> wrote: > > Today's linux-next merge of the akpm-current tree got a conflict in: > > arch/x86/mm/tlb.c > > between commit: > > 83ce56f712af ("x86/mm: Refactor cond_ibpb() to support other use cases") > > from the tip tree and commit: > > 36c8e34d03a1 ("x86/mm: remove vmalloc faulting") > > from the akpm-current tree. > > diff --cc arch/x86/mm/tlb.c > index c8524c506ab0,f3fe261e5936..000000000000 > --- a/arch/x86/mm/tlb.c > +++ b/arch/x86/mm/tlb.c > @@@ -345,48 -161,16 +345,20 @@@ void switch_mm(struct mm_struct *prev, > local_irq_restore(flags); > } > > - static void sync_current_stack_to_mm(struct mm_struct *mm) > - { > - unsigned long sp = current_stack_pointer; > - pgd_t *pgd = pgd_offset(mm, sp); > - > - if (pgtable_l5_enabled()) { > - if (unlikely(pgd_none(*pgd))) { > - pgd_t *pgd_ref = pgd_offset_k(sp); > - > - set_pgd(pgd, *pgd_ref); > - } > - } else { > - /* > - * "pgd" is faked. The top level entries are "p4d"s, so sync > - * the p4d. This compiles to approximately the same code as > - * the 5-level case. > - */ > - p4d_t *p4d = p4d_offset(pgd, sp); > - > - if (unlikely(p4d_none(*p4d))) { > - pgd_t *pgd_ref = pgd_offset_k(sp); > - p4d_t *p4d_ref = p4d_offset(pgd_ref, sp); > - > - set_p4d(p4d, *p4d_ref); > - } > - } > - } > - > -static inline unsigned long mm_mangle_tif_spec_ib(struct task_struct *next) > +static inline unsigned long mm_mangle_tif_spec_bits(struct task_struct > *next) > { > unsigned long next_tif = task_thread_info(next)->flags; > - unsigned long ibpb = (next_tif >> TIF_SPEC_IB) & LAST_USER_MM_IBPB; > + unsigned long spec_bits = (next_tif >> TIF_SPEC_IB) & > LAST_USER_MM_SPEC_MASK; > > - return (unsigned long)next->mm | ibpb; > + BUILD_BUG_ON(TIF_SPEC_L1D_FLUSH != TIF_SPEC_IB + 1); > + > + return (unsigned long)next->mm | spec_bits; > } > > -static void cond_ibpb(struct task_struct *next) > +static void cond_mitigation(struct task_struct *next) > { > + unsigned long prev_mm, next_mm; > + > if (!next || !next->mm) > return; > > @@@ -587,20 -343,12 +559,11 @@@ void switch_mm_irqs_off(struct mm_struc > need_flush = true; > } else { > /* > - * Avoid user/user BTB poisoning by flushing the branch > - * predictor when switching between processes. This stops > - * one process from doing Spectre-v2 attacks on another. > + * Apply process to process speculation vulnerability > + * mitigations if applicable. > */ > - cond_ibpb(tsk); > + cond_mitigation(tsk); > > - if (IS_ENABLED(CONFIG_VMAP_STACK)) { > - /* > - * If our current stack is in vmalloc space and isn't > - * mapped in the new pgd, we'll double-fault. Forcibly > - * map it. > - */ > - sync_current_stack_to_mm(next); > - } > - > /* > * Stop remote flushes for the previous mm. > * Skip kernel threads; we never send init_mm TLB flushing IPIs,
This is now a conflict between commit
94709049fb84 ("Merge branch 'akpm' (patches from Andrew)")
from Linus' tree and the above tip tree commit.
--
Cheers,
Stephen Rothwell
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