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Alpha systems can suffer sporadic user-space crashes and heap corruption when memory compaction is enabled. Symptoms include SIGSEGV, glibc allocator failures (e.g. "unaligned tcache chunk"), and compiler internal errors. The failures disappear when compaction is disabled or when using global TLB invalidation. The root cause is insufficient TLB shootdown during page migration. Alpha relies on ASN-based MM context rollover for instruction cache coherency, but this alone is not sufficient to prevent stale data or instruction translations from surviving migration. Fix this by introducing a migration-specific helper that combines: - MM context invalidation (ASN rollover), - immediate per-CPU TLB invalidation (TBI), - synchronous cross-CPU shootdown when required. The helper is used only by migration/compaction paths to avoid changing global TLB semantics. Additionally, update flush_tlb_other(), pte_clear(), to use READ_ONCE()/WRITE_ONCE() for correct SMP memory ordering. This fixes observed crashes on both UP and SMP Alpha systems. Reviewed-by: Ivan Kokshaysky <ink@unseen.parts> Tested-by: Matoro Mahri <matoro_mailinglist_kernel@matoro.tk> Tested-by: Michael Cree <mcree@orcon.net.nz> Signed-off-by: Magnus Lindholm <linmag7@gmail.com> Link: https://lore.kernel.org/r/20260102173603.18247-2-linmag7@gmail.com Signed-off-by: Magnus Lindholm <linmag7@gmail.com>
121 lines
2.6 KiB
C
121 lines
2.6 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _ALPHA_TLBFLUSH_H
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#define _ALPHA_TLBFLUSH_H
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#include <linux/mm.h>
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#include <linux/sched.h>
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#include <asm/compiler.h>
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#ifndef __EXTERN_INLINE
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#define __EXTERN_INLINE extern inline
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#define __MMU_EXTERN_INLINE
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#endif
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extern void __load_new_mm_context(struct mm_struct *);
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__EXTERN_INLINE void
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ev5_flush_tlb_current(struct mm_struct *mm)
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{
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__load_new_mm_context(mm);
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}
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/* Flush just one page in the current TLB set. We need to be very
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careful about the icache here, there is no way to invalidate a
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specific icache page. */
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__EXTERN_INLINE void
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ev5_flush_tlb_current_page(struct mm_struct * mm,
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struct vm_area_struct *vma,
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unsigned long addr)
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{
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if (vma->vm_flags & VM_EXEC)
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__load_new_mm_context(mm);
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else
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tbi(2, addr);
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}
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#define flush_tlb_current ev5_flush_tlb_current
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#define flush_tlb_current_page ev5_flush_tlb_current_page
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#ifdef __MMU_EXTERN_INLINE
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#undef __EXTERN_INLINE
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#undef __MMU_EXTERN_INLINE
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#endif
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/* Flush current user mapping. */
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static inline void
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flush_tlb(void)
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{
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flush_tlb_current(current->active_mm);
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}
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/* Flush someone else's user mapping. */
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static inline void
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flush_tlb_other(struct mm_struct *mm)
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{
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unsigned long *mmc = &mm->context[smp_processor_id()];
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/* Check it's not zero first to avoid cacheline ping pong
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when possible. */
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if (READ_ONCE(*mmc))
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WRITE_ONCE(*mmc, 0);
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}
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#ifndef CONFIG_SMP
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/* Flush everything (kernel mapping may also have changed
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due to vmalloc/vfree). */
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static inline void flush_tlb_all(void)
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{
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tbia();
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}
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/* Flush a specified user mapping. */
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static inline void
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flush_tlb_mm(struct mm_struct *mm)
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{
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if (mm == current->active_mm)
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flush_tlb_current(mm);
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else
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flush_tlb_other(mm);
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}
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/* Page-granular tlb flush. */
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static inline void
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flush_tlb_page(struct vm_area_struct *vma, unsigned long addr)
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{
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struct mm_struct *mm = vma->vm_mm;
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if (mm == current->active_mm)
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flush_tlb_current_page(mm, vma, addr);
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else
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flush_tlb_other(mm);
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}
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/* Flush a specified range of user mapping. On the Alpha we flush
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the whole user tlb. */
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static inline void
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flush_tlb_range(struct vm_area_struct *vma, unsigned long start,
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unsigned long end)
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{
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flush_tlb_mm(vma->vm_mm);
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}
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#else /* CONFIG_SMP */
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extern void flush_tlb_all(void);
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extern void flush_tlb_mm(struct mm_struct *);
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extern void flush_tlb_page(struct vm_area_struct *, unsigned long);
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extern void flush_tlb_range(struct vm_area_struct *, unsigned long,
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unsigned long);
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#endif /* CONFIG_SMP */
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static inline void flush_tlb_kernel_range(unsigned long start,
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unsigned long end)
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{
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flush_tlb_all();
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}
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#endif /* _ALPHA_TLBFLUSH_H */
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