uprobes: turn xol_area->pages[2] into xol_area->page

Now that xol_mapping has its own ->fault() method we no longer need
xol_area->pages[1] == NULL, we need a single page.

Link: https://lkml.kernel.org/r/20240911131437.GC3448@redhat.com
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index a478e028043f8faf0efead02748c4f782ab16d0d..94a17435cfe62b8229b6d0140ac384b11cf1bf12 100644 (file)
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -99,7 +99,7 @@ struct xol_area {
        atomic_t                        slot_count;     /* number of in-use slots */
        unsigned long                   *bitmap;        /* 0 = free slot */
 
-       struct page                     *pages[2];
+       struct page                     *page;
        /*
         * We keep the vma's vm_start rather than a pointer to the vma
         * itself.  The probed process or a naughty kernel module could make
@@ -1437,7 +1437,7 @@ static vm_fault_t xol_fault(const struct vm_special_mapping *sm,
 {
        struct xol_area *area = vma->vm_mm->uprobes_state.xol_area;
 
-       vmf->page = area->pages[0];
+       vmf->page = area->page;
        get_page(vmf->page);
        return 0;
 }
@@ -1512,10 +1512,9 @@ static struct xol_area *__create_xol_area(unsigned long vaddr)
        if (!area->bitmap)
                goto free_area;
 
-       area->pages[0] = alloc_page(GFP_HIGHUSER);
-       if (!area->pages[0])
+       area->page = alloc_page(GFP_HIGHUSER);
+       if (!area->page)
                goto free_bitmap;
-       area->pages[1] = NULL;
 
        area->vaddr = vaddr;
        init_waitqueue_head(&area->wq);
@@ -1523,12 +1522,12 @@ static struct xol_area *__create_xol_area(unsigned long vaddr)
        set_bit(0, area->bitmap);
        atomic_set(&area->slot_count, 1);
        insns = arch_uprobe_trampoline(&insns_size);
-       arch_uprobe_copy_ixol(area->pages[0], 0, insns, insns_size);
+       arch_uprobe_copy_ixol(area->page, 0, insns, insns_size);
 
        if (!xol_add_vma(mm, area))
                return area;
 
-       __free_page(area->pages[0]);
+       __free_page(area->page);
  free_bitmap:
        kfree(area->bitmap);
  free_area:
@@ -1570,7 +1569,7 @@ void uprobe_clear_state(struct mm_struct *mm)
        if (!area)
                return;
 
-       put_page(area->pages[0]);
+       put_page(area->page);
        kfree(area->bitmap);
        kfree(area);
 }
@@ -1637,7 +1636,7 @@ static unsigned long xol_get_insn_slot(struct uprobe *uprobe)
        if (unlikely(!xol_vaddr))
                return 0;
 
-       arch_uprobe_copy_ixol(area->pages[0], xol_vaddr,
+       arch_uprobe_copy_ixol(area->page, xol_vaddr,
                              &uprobe->arch.ixol, sizeof(uprobe->arch.ixol));
 
        return xol_vaddr;