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05 April 2024, 19:05:47 UTC
Revision 854236363370995a609a10b03e35fd3dc5e9e4a1 authored by James Hogan on 29 June 2017, 14:05:04 UTC, committed by Ralf Baechle on 30 June 2017, 02:42:15 UTC 
MIPS: Avoid accidental raw backtrace
 
Since commit 81a76d7119f6 ("MIPS: Avoid using unwind_stack() with
usermode") show_backtrace() invokes the raw backtracer when
cp0_status & ST0_KSU indicates user mode to fix issues on EVA kernels
where user and kernel address spaces overlap.

However this is used by show_stack() which creates its own pt_regs on
the stack and leaves cp0_status uninitialised in most of the code paths.
This results in the non deterministic use of the raw back tracer
depending on the previous stack content.

show_stack() deals exclusively with kernel mode stacks anyway, so
explicitly initialise regs.cp0_status to KSU_KERNEL (i.e. 0) to ensure
we get a useful backtrace.

Fixes: 81a76d7119f6 ("MIPS: Avoid using unwind_stack() with usermode")
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: <stable@vger.kernel.org> # 3.15+
Patchwork: https://patchwork.linux-mips.org/patch/16656/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
1 parent cad482c
History
Tip revision: 854236363370995a609a10b03e35fd3dc5e9e4a1 authored by James Hogan on 29 June 2017, 14:05:04 UTC
MIPS: Avoid accidental raw backtrace
Tip revision: 8542363
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