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authorOleg Nesterov <oleg@redhat.com>2012-09-23 21:55:19 +0200
committerAnton Arapov <anton@redhat.com>2012-10-29 11:47:47 +0100
commitc1ee69c19b3bf0d8f4e26306cccdf4398be29cb6 (patch)
tree83373e5aa29b6409a9f42fb112c793b0a3629739
parent7240b0266ebd54a504900fe55f5ae272a73cfa07 (diff)
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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>
-rw-r--r--kernel/events/uprobes.c73
1 files changed, 24 insertions, 49 deletions
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 9248ee7..6136854 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -282,32 +282,6 @@ put_old:
return ret;
}
-static int is_swbp_at_addr(struct mm_struct *mm, unsigned long vaddr)
-{
- struct page *page;
- uprobe_opcode_t opcode;
- int result;
-
- if (current->mm == mm) {
- pagefault_disable();
- result = __copy_from_user_inatomic(&opcode, (void __user*)vaddr,
- sizeof(opcode));
- pagefault_enable();
-
- if (likely(result == 0))
- goto out;
- }
-
- result = get_user_pages(NULL, mm, vaddr, 1, 0, 1, &page, NULL);
- if (result < 0)
- return result;
-
- copy_opcode(page, vaddr, &opcode);
- put_page(page);
- out:
- return is_swbp_insn(&opcode);
-}
-
/**
* set_swbp - store breakpoint at a given address.
* @auprobe: arch specific probepoint information.
@@ -589,29 +563,6 @@ static int copy_insn(struct uprobe *uprobe, struct file *filp)
return __copy_insn(mapping, filp, uprobe->arch.insn, bytes, uprobe->offset);
}
-/*
- * How mm->uprobes_state.count gets updated
- * uprobe_mmap() increments the count if
- * - it successfully adds a breakpoint.
- * - it cannot add a breakpoint, but sees that there is a underlying
- * breakpoint (via a is_swbp_at_addr()).
- *
- * uprobe_munmap() decrements the count if
- * - it sees a underlying breakpoint, (via is_swbp_at_addr)
- * (Subsequent uprobe_unregister wouldnt find the breakpoint
- * unless a uprobe_mmap kicks in, since the old vma would be
- * dropped just after uprobe_munmap.)
- *
- * uprobe_register increments the count if:
- * - it successfully adds a breakpoint.
- *
- * uprobe_unregister decrements the count if:
- * - it sees a underlying breakpoint and removes successfully.
- * (via is_swbp_at_addr)
- * (Subsequent uprobe_munmap wouldnt find the breakpoint
- * since there is no underlying breakpoint after the
- * breakpoint removal.)
- */
static int
install_breakpoint(struct uprobe *uprobe, struct mm_struct *mm,
struct vm_area_struct *vma, unsigned long vaddr)
@@ -1389,6 +1340,30 @@ static void mmf_recalc_uprobes(struct mm_struct *mm)
clear_bit(MMF_HAS_UPROBES, &mm->flags);
}
+static int is_swbp_at_addr(struct mm_struct *mm, unsigned long vaddr)
+{
+ struct page *page;
+ uprobe_opcode_t opcode;
+ int result;
+
+ pagefault_disable();
+ result = __copy_from_user_inatomic(&opcode, (void __user*)vaddr,
+ sizeof(opcode));
+ pagefault_enable();
+
+ if (likely(result == 0))
+ goto out;
+
+ result = get_user_pages(NULL, mm, vaddr, 1, 0, 1, &page, NULL);
+ if (result < 0)
+ return result;
+
+ copy_opcode(page, vaddr, &opcode);
+ put_page(page);
+ out:
+ return is_swbp_insn(&opcode);
+}
+
static struct uprobe *find_active_uprobe(unsigned long bp_vaddr, int *is_swbp)
{
struct mm_struct *mm = current->mm;