[PATCH] uboot-lantiq: fix out of bounds cache invalidate

[Mathias Kresin]

If u-boot is compiled with gcc 10+ the relevant part of the memory is
used as following:

variable BootFile is at address: 0x83ffe4ec
variable data is at address:     0x83ffdee2
variable data has len:           0x600

Within invalidate_dcache_range() the cache covering the data variable
should be invalidated (0x83ffdee2 till 0x83ffdef2).

Due to dcache line size of 32 and some alignment correction, the actual
memory range for which the cache is invalidated is from 0x83ffdee0 till
0x83ffe500, which includes the location of the BootFile variable as
well.

Afterwards the BootFile variable is 0. The issue can be observed by
using tftpboot, which always uses the default/generated filename instead
of the specified one.

To fix the issue, align the memory addresses properly before passing
them to invalidate_dcache_range(). The misalignment can be observed with
older gcc versions as well but the BootFile variable is placed more than
0x1000 bytes after the data variable and doesn't get null'ed.

Fixes: FS#4113

Signed-off-by: Mathias Kresin <dev at kresin.me>
---
 ...q-fix-out-of-bounds-cache-invalidate.patch | 48 +++++++++++++++++++
 1 file changed, 48 insertions(+)
 create mode 100644 package/boot/uboot-lantiq/patches/0031-dma-lantiq-fix-out-of-bounds-cache-invalidate.patch

diff --git a/package/boot/uboot-lantiq/patches/0031-dma-lantiq-fix-out-of-bounds-cache-invalidate.patch b/package/boot/uboot-lantiq/patches/0031-dma-lantiq-fix-out-of-bounds-cache-invalidate.patch
new file mode 100644
index 0000000000..5a2bf39441
--- /dev/null
+++ b/package/boot/uboot-lantiq/patches/0031-dma-lantiq-fix-out-of-bounds-cache-invalidate.patch
@@ -0,0 +1,48 @@
+From f10ffb65865d5bfa5679293b13e027e0474df1fe Mon Sep 17 00:00:00 2001
+From: Mathias Kresin <dev at kresin.me>
+Date: Tue, 2 Nov 2021 21:24:29 +0100
+Subject: [PATCH] dma: lantiq: fix out of bounds cache invalidate
+
+If u-boot is compiled with gcc 10+ the relevant part of the memory is
+used as following:
+
+variable BootFile is at address: 0x83ffe4ec
+variable data is at address:     0x83ffdee2
+variable data has len:           0x600
+
+Within invalidate_dcache_range() the cache covering the data variable
+should be invalidated (0x83ffdee2 till 0x83ffdef2).
+
+Due to dcache line size of 32 and some alignment correction, the actual
+memory range for which the cache is invalidated is from 0x83ffdee0 till
+0x83ffe500, which includes the location of the BootFile variable as
+well.
+
+Afterwards the BootFile variable is 0. The issue can be observed by
+using tftpboot, which always uses the default/generated filename instead
+of the specified one.
+
+To fix the issue, align the memory addresses properly before passing
+them to invalidate_dcache_range(). The misalignment can be observed with
+older gcc versions as well but the BootFile variable is placed more than
+0x1000 bytes after the data variable and doesn't get null'ed.
+
+Signed-off-by: Mathias Kresin <dev at kresin.me>
+---
+ drivers/dma/lantiq_dma.c | 4 ++--
+ 1 file changed, 2 insertions(+), 2 deletions(-)
+
+--- a/drivers/dma/lantiq_dma.c
++++ b/drivers/dma/lantiq_dma.c
+@@ -122,9 +122,9 @@ static inline void ltq_dma_dcache_wb_inv
+ 
+ static inline void ltq_dma_dcache_inv(const void *ptr, size_t size)
+ {
+-	unsigned long addr = (unsigned long) ptr;
++	unsigned long addr = (unsigned long) ptr & ~(ARCH_DMA_MINALIGN - 1);
+ 
+-	invalidate_dcache_range(addr, addr + size);
++	invalidate_dcache_range(addr, ALIGN(addr + size, ARCH_DMA_MINALIGN));
+ }
+ 
+ void ltq_dma_init(void)
-- 
2.25.1