Re: How to get past ebreak instruction on RISC-V

[Simon Marchi <simon.marchi@polymtl.ca>]

On 2021-01-12 11:07 a.m., Jan Vrany wrote:
> Hi, 
> 
> I'm working on RISC-V compiler. To ease debugging of compiled code
> I'm inserting `ebreak` instruction to interesting place (entry/exit
> points or as a placeholder for unimplemented features). 
> 
> For example, the code might look like:
> 
> (gdb) disas 0x0000003FD6A36024, 0x0000003FD6A36048
> Dump of assembler code from 0x3fd6a36024 to 0x3fd6a36048:
> => 0x0000003fd6a36024:  ebreak
>    0x0000003fd6a36028:  sd      ra,-8(s11)
>    0x0000003fd6a3602c:  addi    s11,s11,-16
>    0x0000003fd6a36030:  ld      t3,80(s10)
>    0x0000003fd6a36034:  addiw   a0,zero,42
>    0x0000003fd6a36038:  addi    s11,s11,16
>    0x0000003fd6a3603c:  ret
>    0x0000003fd6a36040:  blt     s11,t3,0x3fd6a36000
>    0x0000003fd6a36044:  ebreak
> End of assembler dump.
> (gdb) 
> 
> When compiled function is (attempted to) run, it stops on `ebreak` 
> as expected: 
> 
> Thread 2 "main" received signal SIGTRAP, Trace/breakpoint trap.
> [Switching to Thread 0x3ff7e681e0 (LWP 428777)]
> 0x0000003fd6a36024 in ?? ()
> 
> How can I get past the `ebreak` so I can `stepi` thought the following
> instructions and debug? Thanks! 

I suppose you could do "set $pc = 0x3fd6a36028".  But really this is
something that GDB should be doing automatically, adjusting the PC
after hitting that style of breakpoint.

Simon