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uprobes: introduce the global struct vm_special_mapping xol_mapping

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Currently each xol_area has its own instance of vm_special_mapping, this
is suboptimal and ugly.  Kill xol_area->xol_mapping and add a single
global instance of vm_special_mapping, the ->fault() method can use
area->pages rather than xol_mapping->pages.

As a side effect this fixes the problem introduced by the recent commit
223febc6e5 ("mm: add optional close() to struct vm_special_mapping"), if
special_mapping_close() is called from the __mmput() paths, it will use
vma->vm_private_data = &area->xol_mapping freed by uprobe_clear_state().

Link: https://lkml.kernel.org/r/20240911131407.GB3448@redhat.com
Fixes: 223febc6e5 ("mm: add optional close() to struct vm_special_mapping")
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reported-by: Sven Schnelle <svens@linux.ibm.com>
Closes: https://lore.kernel.org/all/yt9dy149vprr.fsf@linux.ibm.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>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Oleg Nesterov 2024-09-11 15:14:07 +02:00 committed by Andrew Morton
parent ed8d5b0ce1
commit 6d27a31ef1
1 changed files with 16 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

21
kernel/events/uprobes.c
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@ -99,7 +99,6 @@ struct xol_area {
atomic_t slot_count; /* number of in-use slots */
unsigned long *bitmap; /* 0 = free slot */
struct vm_special_mapping xol_mapping;
struct page *pages[2];
/*
* We keep the vma's vm_start rather than a pointer to the vma
@ -1433,6 +1432,21 @@ void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned lon
set_bit(MMF_RECALC_UPROBES, &vma->vm_mm->flags);
}
static vm_fault_t xol_fault(const struct vm_special_mapping *sm,
struct vm_area_struct *vma, struct vm_fault *vmf)
{
struct xol_area *area = vma->vm_mm->uprobes_state.xol_area;
vmf->page = area->pages[0];
get_page(vmf->page);
return 0;
}
static const struct vm_special_mapping xol_mapping = {
.name = "[uprobes]",
.fault = xol_fault,
};
/* Slot allocation for XOL */
static int xol_add_vma(struct mm_struct *mm, struct xol_area *area)
{
@ -1459,7 +1473,7 @@ static int xol_add_vma(struct mm_struct *mm, struct xol_area *area)
vma = _install_special_mapping(mm, area->vaddr, PAGE_SIZE,
VM_EXEC|VM_MAYEXEC|VM_DONTCOPY|VM_IO,
&area->xol_mapping);
&xol_mapping);
if (IS_ERR(vma)) {
ret = PTR_ERR(vma);
goto fail;
@ -1498,9 +1512,6 @@ static struct xol_area *__create_xol_area(unsigned long vaddr)
if (!area->bitmap)
goto free_area;
area->xol_mapping.name = "[uprobes]";
area->xol_mapping.fault = NULL;
area->xol_mapping.pages = area->pages;
area->pages[0] = alloc_page(GFP_HIGHUSER);
if (!area->pages[0])
goto free_bitmap;