Re: [Qemu-devel] [PULL 17/29] target/riscv: Convert quadrant 1 of RVXC insns to decodetree

[Palmer Dabbelt]

On Fri, 15 Mar 2019 02:06:07 PDT (-0700), Bastian Koppelmann wrote:
> Hi Alistair
>
> On 3/14/19 9:28 PM, Alistair Francis wrote:
> > On Wed, Mar 13, 2019 at 7:53 AM Palmer Dabbelt <address@hidden> wrote:
> > > From: Bastian Koppelmann <address@hidden>
> > >
> > > Reviewed-by: Richard Henderson <address@hidden>
> > > Signed-off-by: Bastian Koppelmann <address@hidden>
> > > Signed-off-by: Peer Adelt <address@hidden>
> > This commit is the first bad commit in breaking 32-bit boot.
> >
> > It looks like the jal doesn't jump to the correct address:
> >
> > ----------------
> > IN:
> > 0x80000022:  00050433          add             s0,a0,zero
> > 0x80000026:  000584b3          add             s1,a1,zero
> > 0x8000002a:  2c79              jal             ra,670          # 0x800002c8
> >
> > ----------------
> > IN:
> > 0x800002c8:  00000533          add             a0,zero,zero
> > 0x800002cc:  8082              ret
>
>
> Oops! Can you point me to the binary to reproduce this?

I think I've traced it down to something simple: in my hello world binary I see

   20401a8c:       2a45                    jal     20401c3c <atexit>

in the objdump, and I see

   IN: _start
   0x20401a8c:  2a45              jal             ra,432          # 0x20401c3c

but then QEMU jumps to 0x20401a9d.  I have a feeling it's something wrong with 
gen_jal() that disappeared during the cleanups that we dropped in order to fix 
the build issues.

I'm running

   ./riscv32-softmmu/qemu-system-riscv32 -machine sifive_e -kernel 
~/work/sifive/freedom-e-sdk/software/hello/hello -nographic -d 
in_asm,out_asm,exec,cpu -singlestep |& tee out.log

on the "hifive1" branch of github.com/palmer-dabbelt/qemu, which just has a 
PRCI fixup that I forgot about and haven't sent upstream yet (I'll do that 
after this issue).  The binary should be at

   http://www.dabbelt.com/~palmer/hello.elf

and the debug log at 

   http://www.dabbelt.com/~palmer/out.log

You can build the binary from github.com/sifive/freedom-e-sdk via

  make software PROGRAM=hello TARGET=sifive-hifive1

using the riscv64-unknown-elf-gcc-20181127-x86_64-linux-ubuntu14 toolchain 
binaries from our website (newer ones should work, but probably won't produce 
exactly the same output).

I'll poke around after grabbing some dinner...