Invalid assertion in arm_read_memory_func

[Christophe Lyon]

Hi,

I think there is an invalid assertion in arm_read_memory_func:
assert(info->endian == BFD_ENDIAN_LITTLE)

I face it in the following use case: target armeb-linux (I use qemu user mode), -d in_asm -cpu any.

At some point during program startup, glibc's _dl_new_object calls strlen, which is written in thumb2 mode (armv6t2). So print_insn_arm() calls arm_read_memory_func() with length==2, and info->flags == INSN_ARM_BE32, and the assert is false.

If I remove the assert, execution continues OK.

With the assert, I get the error message from the assert, and qemu then stalls.

Can you confirm the assert can be removed? Or if not, explain me how to avoid/fix the subsequent qemu stall?

Thanks

[Christophe Lyon (christophe-lyon)]

The tarball contains:
scoped1.exe
etc/ld.so.cache
lib/libm.so.6
lib/libstdc++.so.6
lib/lib.c.so.6
lib/ld-linux-armhf.so.3
lib/libgcc_s.so.1

I can reproduce the problem with qemu-2.10.1:
qemu-armeb -E LD_LIBRARY_PATH=$PWD/lib -cpu any -R 0 -d in_asm -L $PWD $PWD/scoped1.exe

Removing '-d in_asm' works OK, because the offending assert is triggered while disassembling.

BTW, the program (scoped1.exe) does abort, it is a GCC testcase I was trying to debug ;-)

Removing the assert lets execution continue, but the disassembly is incorrect. Without the assert, I see:
IN: strlen
0x40a1a880: f000 f890 bl 0x40a1a9a4
0x40a1a884: 4502 cmp r2, r0
but strlen normally starts with a pld instruction.

So probably print_insn_arm needs also a change like
given = (b[1]) | (b[0] <<8)<<16 | given;
instead of
given = (b[1]) | (b[0] <<8)|(given << 16);

[Peter Maydell (pmaydell)]

This should be fixed in QEMU master by commits 6cd61517fb5217098, 7bcdbf51eeb674e4.