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uprobes: Simplify is_swbp_at_addr(), remove stale comments
After the previous change is_swbp_at_addr() is always called with current->mm. Remove this check and move it close to its single caller. Also, remove the obsolete comment about is_swbp_at_addr() and uprobe_state.count. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
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@ -282,32 +282,6 @@ put_old:
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return ret;
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}
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static int is_swbp_at_addr(struct mm_struct *mm, unsigned long vaddr)
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{
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struct page *page;
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uprobe_opcode_t opcode;
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int result;
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if (current->mm == mm) {
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pagefault_disable();
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result = __copy_from_user_inatomic(&opcode, (void __user*)vaddr,
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sizeof(opcode));
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pagefault_enable();
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if (likely(result == 0))
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goto out;
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}
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result = get_user_pages(NULL, mm, vaddr, 1, 0, 1, &page, NULL);
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if (result < 0)
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return result;
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copy_opcode(page, vaddr, &opcode);
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put_page(page);
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out:
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return is_swbp_insn(&opcode);
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}
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/**
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* set_swbp - store breakpoint at a given address.
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* @auprobe: arch specific probepoint information.
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@ -589,29 +563,6 @@ static int copy_insn(struct uprobe *uprobe, struct file *filp)
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return __copy_insn(mapping, filp, uprobe->arch.insn, bytes, uprobe->offset);
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}
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/*
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* How mm->uprobes_state.count gets updated
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* uprobe_mmap() increments the count if
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* - it successfully adds a breakpoint.
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* - it cannot add a breakpoint, but sees that there is a underlying
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* breakpoint (via a is_swbp_at_addr()).
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*
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* uprobe_munmap() decrements the count if
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* - it sees a underlying breakpoint, (via is_swbp_at_addr)
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* (Subsequent uprobe_unregister wouldnt find the breakpoint
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* unless a uprobe_mmap kicks in, since the old vma would be
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* dropped just after uprobe_munmap.)
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*
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* uprobe_register increments the count if:
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* - it successfully adds a breakpoint.
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*
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* uprobe_unregister decrements the count if:
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* - it sees a underlying breakpoint and removes successfully.
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* (via is_swbp_at_addr)
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* (Subsequent uprobe_munmap wouldnt find the breakpoint
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* since there is no underlying breakpoint after the
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* breakpoint removal.)
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*/
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static int
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install_breakpoint(struct uprobe *uprobe, struct mm_struct *mm,
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struct vm_area_struct *vma, unsigned long vaddr)
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@ -1389,6 +1340,30 @@ static void mmf_recalc_uprobes(struct mm_struct *mm)
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clear_bit(MMF_HAS_UPROBES, &mm->flags);
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}
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static int is_swbp_at_addr(struct mm_struct *mm, unsigned long vaddr)
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{
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struct page *page;
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uprobe_opcode_t opcode;
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int result;
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pagefault_disable();
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result = __copy_from_user_inatomic(&opcode, (void __user*)vaddr,
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sizeof(opcode));
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pagefault_enable();
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if (likely(result == 0))
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goto out;
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result = get_user_pages(NULL, mm, vaddr, 1, 0, 1, &page, NULL);
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if (result < 0)
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return result;
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copy_opcode(page, vaddr, &opcode);
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put_page(page);
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out:
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return is_swbp_insn(&opcode);
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}
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static struct uprobe *find_active_uprobe(unsigned long bp_vaddr, int *is_swbp)
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{
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struct mm_struct *mm = current->mm;
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