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To:     Arnd Bergmann <arnd@arndb.de>,
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Cc:     linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org,
        Quanyang Wang <quanyang.wang@windriver.com>
Subject: [PATCH] asm/sections: fix the determination of the end of the memory region
Date:   Thu, 11 Aug 2022 14:31:05 +0800
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From: Quanyang Wang <quanyang.wang@windriver.com>

If using "vend >= begin" to judge if two memory regions intersects, vend
should be the end of the memory region, so it should be "virt + size -1"
instead of "virt + size".
The wrong determination of the end triggers the misreporting as below when
the dma debug function "check_for_illegal_area" calls memory_intersects to
check if the dma region intersects with stext region.

Calltrace (stext is at 0x80100000):
 WARNING: CPU: 0 PID: 77 at kernel/dma/debug.c:1073 check_for_illegal_area+0x130/0x168
 DMA-API: chipidea-usb2 e0002000.usb: device driver maps memory from kernel text or rodata [addr=800f0000] [len=65536]
 Modules linked in:
 CPU: 1 PID: 77 Comm: usb-storage Not tainted 5.19.0-yocto-standard #5
 Hardware name: Xilinx Zynq Platform
  unwind_backtrace from show_stack+0x18/0x1c
  show_stack from dump_stack_lvl+0x58/0x70
  dump_stack_lvl from __warn+0xb0/0x198
  __warn from warn_slowpath_fmt+0x80/0xb4
  warn_slowpath_fmt from check_for_illegal_area+0x130/0x168
  check_for_illegal_area from debug_dma_map_sg+0x94/0x368
  debug_dma_map_sg from __dma_map_sg_attrs+0x114/0x128
  __dma_map_sg_attrs from dma_map_sg_attrs+0x18/0x24
  dma_map_sg_attrs from usb_hcd_map_urb_for_dma+0x250/0x3b4
  usb_hcd_map_urb_for_dma from usb_hcd_submit_urb+0x194/0x214
  usb_hcd_submit_urb from usb_sg_wait+0xa4/0x118
  usb_sg_wait from usb_stor_bulk_transfer_sglist+0xa0/0xec
  usb_stor_bulk_transfer_sglist from usb_stor_bulk_srb+0x38/0x70
  usb_stor_bulk_srb from usb_stor_Bulk_transport+0x150/0x360
  usb_stor_Bulk_transport from usb_stor_invoke_transport+0x38/0x440
  usb_stor_invoke_transport from usb_stor_control_thread+0x1e0/0x238
  usb_stor_control_thread from kthread+0xf8/0x104
  kthread from ret_from_fork+0x14/0x2c

Fixes: 979559362516 ("asm/sections: add helpers to check for section data")
Signed-off-by: Quanyang Wang <quanyang.wang@windriver.com>
---
 include/asm-generic/sections.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/asm-generic/sections.h b/include/asm-generic/sections.h
index d0f7bdd2fdf2..f7171b4f5bfd 100644
--- a/include/asm-generic/sections.h
+++ b/include/asm-generic/sections.h
@@ -108,7 +108,7 @@ static inline bool memory_contains(void *begin, void *end, void *virt,
 static inline bool memory_intersects(void *begin, void *end, void *virt,
 				     size_t size)
 {
-	void *vend = virt + size;
+	void *vend = virt + size - 1;
 
 	return (virt >= begin && virt < end) || (vend >= begin && vend < end);
 }
-- 
2.36.1