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Subject[PATCH] powerpc/msi: Remove VLA usage
In the quest to remove all stack VLA usage from the kernel[1], this
switches from an unchanging variable to a constant expression to eliminate
the VLA generation.

[1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com

Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Tyrel Datwyler <tyreld@linux.vnet.ibm.com>
Cc: Rob Herring <robh@kernel.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: Kees Cook <keescook@chromium.org>
---
arch/powerpc/sysdev/msi_bitmap.c | 15 ++++++++-------
1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/arch/powerpc/sysdev/msi_bitmap.c b/arch/powerpc/sysdev/msi_bitmap.c
index 6243a7e537d0..e64a411d1a00 100644
--- a/arch/powerpc/sysdev/msi_bitmap.c
+++ b/arch/powerpc/sysdev/msi_bitmap.c
@@ -225,22 +225,23 @@ static void __init test_of_node(void)
struct device_node of_node;
struct property prop;
struct msi_bitmap bmp;
- int size = 256;
- DECLARE_BITMAP(expected, size);
+#define SIZE_EXPECTED 256
+ DECLARE_BITMAP(expected, SIZE_EXPECTED);

/* There should really be a struct device_node allocator */
memset(&of_node, 0, sizeof(of_node));
of_node_init(&of_node);
of_node.full_name = node_name;

- WARN_ON(msi_bitmap_alloc(&bmp, size, &of_node));
+ WARN_ON(msi_bitmap_alloc(&bmp, SIZE_EXPECTED, &of_node));

/* No msi-available-ranges, so expect > 0 */
WARN_ON(msi_bitmap_reserve_dt_hwirqs(&bmp) <= 0);

/* Should all still be free */
- WARN_ON(bitmap_find_free_region(bmp.bitmap, size, get_count_order(size)));
- bitmap_release_region(bmp.bitmap, 0, get_count_order(size));
+ WARN_ON(bitmap_find_free_region(bmp.bitmap, SIZE_EXPECTED,
+ get_count_order(SIZE_EXPECTED)));
+ bitmap_release_region(bmp.bitmap, 0, get_count_order(SIZE_EXPECTED));

/* Now create a fake msi-available-ranges property */

@@ -256,8 +257,8 @@ static void __init test_of_node(void)
WARN_ON(msi_bitmap_reserve_dt_hwirqs(&bmp));

/* Check we got the expected result */
- WARN_ON(bitmap_parselist(expected_str, expected, size));
- WARN_ON(!bitmap_equal(expected, bmp.bitmap, size));
+ WARN_ON(bitmap_parselist(expected_str, expected, SIZE_EXPECTED));
+ WARN_ON(!bitmap_equal(expected, bmp.bitmap, SIZE_EXPECTED));

msi_bitmap_free(&bmp);
kfree(bmp.bitmap);
--
2.17.1

--
Kees Cook
Pixel Security

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