riscv: show code leading to exception
To make analyzing exceptions easier output the code that leads to it.
We already do the same on the ARM platform.
Here is an example:
=> exception ebreak
Unhandled exception: Breakpoint
EPC: 000000008ff5d50e RA: 000000008ff5d62c TVAL: 0000000000000000
EPC: 000000008020b50e RA: 000000008020b62c reloc adjusted
Code: 2785 0693 07a0 dce3 fef6 47a5 d563 00e7 (9002)
To disassemble the code we can use the decodecode script:
$ echo 'Code: 2785 0693 07a0 dce3 fef6 47a5 d563 00e7 (9002)' | \
CROSS_COMPILE=riscv64-linux-gnu- scripts/decodecode
Code: 2785 0693 07a0 dce3 fef6 47a5 d563 00e7 (9002)
All code
========
0: 2785 addiw a5,a5,1
2: 07a00693 li a3,122
6: fef6dce3 bge a3,a5,0xfffffffffffffffe
a: 47a5 li a5,9
c: 00e7d563 bge a5,a4,0x16
10:* 9002 ebreak <-- trapping instruction
...
Code starting with the faulting instruction
===========================================
0: 9002 ebreak
...
As it is not always clear if the first 16 bits are at the start or in the
middle of a 32bit instruction it may become necessary to strip the first
u16 from the output before calling decodecode to get the correct
disassembled code.
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Sean Anderson <seanga2@gmail.com>
1 file changed