• Quanyang Wang's avatar
    asm-generic: sections: refactor memory_intersects · 0c7d7cc2
    Quanyang Wang authored
    There are two problems with the current code of memory_intersects:
    
    First, it doesn't check whether the region (begin, end) falls inside the
    region (virt, vend), that is (virt < begin && vend > end).
    
    The second problem is if vend is equal to begin, it will return true but
    this is wrong since vend (virt + size) is not the last address of the
    memory region but (virt + size -1) is.  The wrong determination will
    trigger the misreporting when the function check_for_illegal_area calls
    memory_intersects to check if the dma region intersects with stext region.
    
    The misreporting is as below (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
    
    Refactor memory_intersects to fix the two problems above.
    
    Before the 1d7db834 ("dma-debug: use memory_intersects()
    directly"), memory_intersects is called only by printk_late_init:
    
    printk_late_init -> init_section_intersects ->memory_intersects.
    
    There were few places where memory_intersects was called.
    
    When commit 1d7db834 ("dma-debug: use memory_intersects()
    directly") was merged and CONFIG_DMA_API_DEBUG is enabled, the DMA
    subsystem uses it to check for an illegal area and the calltrace above
    is triggered.
    
    [akpm@linux-foundation.org: fix nearby comment typo]
    Link: https://lkml.kernel.org/r/20220819081145.948016-1-quanyang.wang@windriver.com
    Fixes: 97955936 ("asm/sections: add helpers to check for section data")
    Signed-off-by: default avatarQuanyang Wang <quanyang.wang@windriver.com>
    Cc: Ard Biesheuvel <ardb@kernel.org>
    Cc: Arnd Bergmann <arnd@arndb.de>
    Cc: Thierry Reding <treding@nvidia.com>
    Cc: <stable@vger.kernel.org>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    0c7d7cc2
sections.h 7.5 KB