df24e1783e
Add minimal vDSO support, which provides the signal trampoline helpers, but none of the userspace syscall helpers like time wrappers. The big benefit of this vDSO implementation is, that we now don't need an executeable stack any longer. PA-RISC is one of the last architectures where an executeable stack was needed in oder to implement the signal trampolines by putting assembly instructions on the stack which then gets executed. Instead the kernel will provide the relevant code in the vDSO page and only put the pointers to the signal information on the stack. By dropping the need for executable stacks we avoid running into issues with applications which want non executable stacks for security reasons. Additionally, alternative stacks on memory areas without exec permissions are supported too. This code is based on an initial implementation by Randolph Chung from 2006: https://lore.kernel.org/linux-parisc/4544A34A.6080700@tausq.org/ I did the porting and lifted the code to current code base. Dave fixed the unwind code so that gdb and glibc are able to backtrace through the code. An additional patch to gdb will be pushed upstream by Dave. Signed-off-by: Helge Deller <deller@gmx.de> Signed-off-by: Dave Anglin <dave.anglin@bell.net> Cc: Randolph Chung <randolph@tausq.org> Signed-off-by: Helge Deller <deller@gmx.de>
70 lines
1.9 KiB
C
70 lines
1.9 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _PARISC_TLBFLUSH_H
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#define _PARISC_TLBFLUSH_H
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/* TLB flushing routines.... */
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#include <linux/mm.h>
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#include <linux/sched.h>
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#include <asm/mmu_context.h>
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extern void flush_tlb_all(void);
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extern void flush_tlb_all_local(void *);
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#define smp_flush_tlb_all() flush_tlb_all()
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int __flush_tlb_range(unsigned long sid,
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unsigned long start, unsigned long end);
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#define flush_tlb_range(vma, start, end) \
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__flush_tlb_range((vma)->vm_mm->context.space_id, start, end)
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#define flush_tlb_kernel_range(start, end) \
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__flush_tlb_range(0, start, end)
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/*
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* flush_tlb_mm()
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*
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* The code to switch to a new context is NOT valid for processes
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* which play with the space id's. Thus, we have to preserve the
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* space and just flush the entire tlb. However, the compilers,
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* dynamic linker, etc, do not manipulate space id's, so there
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* could be a significant performance benefit in switching contexts
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* and not flushing the whole tlb.
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*/
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static inline void flush_tlb_mm(struct mm_struct *mm)
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{
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BUG_ON(mm == &init_mm); /* Should never happen */
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#if 1 || defined(CONFIG_SMP)
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/* Except for very small threads, flushing the whole TLB is
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* faster than using __flush_tlb_range. The pdtlb and pitlb
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* instructions are very slow because of the TLB broadcast.
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* It might be faster to do local range flushes on all CPUs
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* on PA 2.0 systems.
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*/
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flush_tlb_all();
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#else
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/* FIXME: currently broken, causing space id and protection ids
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* to go out of sync, resulting in faults on userspace accesses.
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* This approach needs further investigation since running many
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* small applications (e.g., GCC testsuite) is faster on HP-UX.
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*/
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if (mm) {
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if (mm->context != 0)
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free_sid(mm->context);
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mm->context = alloc_sid();
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if (mm == current->active_mm)
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load_context(mm->context);
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}
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#endif
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}
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static inline void flush_tlb_page(struct vm_area_struct *vma,
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unsigned long addr)
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{
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purge_tlb_entries(vma->vm_mm, addr);
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}
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#endif
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