Re: [PATCH v7 00/14] linux-user: brk fixes

[Helge Deller]

On 8/3/23 15:11, Joel Stanley wrote:
> Hi Richard,
>
> On Thu, 3 Aug 2023 at 01:53, Richard Henderson
> <richard.henderson@linaro.org> wrote:
> > Builds on Helge's v6, incorporating my feedback plus
> > some other minor cleanup.
>
> This succeeds for the armhf static binary on ppc64le host that was
> previously segfaulting.
>
> However, the arm static binary on ppc64le host now segfaults:
>
> $ gdb -q -ex r --args ./build/qemu-arm -d guest_errors,page,strace ~/hello
> Reading symbols from ./build/qemu-arm...
> Starting program: /scratch/joel/qemu/build/qemu-arm -d
> guest_errors,page,strace /home/joel/hello
> [Thread debugging using libthread_db enabled]
> Using host libthread_db library "/lib/powerpc64le-linux-gnu/libthread_db.so.1".
> [New Thread 0x7ffff762ece0 (LWP 143553)]
> host mmap_min_addr=0x10000
> pgb_find_hole: base @ 140420000 for 4294967296 bytes
> pgb_static: base @ 140420000 for 4294967295 bytes
> pgb_reserved_va: base @ 0x140420000 for 4294967296 bytes
> Locating guest address space @ 0x140420000
> page layout changed following mmap
> start    end      size     prot
> 00010000-00090000 00080000 ---
> 00090000-0009b000 0000b000 ---
> ffff0000-00000000 00010000 r-x
> page layout changed following mmap
> start    end      size     prot
> 00010000-00090000 00080000 r-x
> 00090000-0009b000 0000b000 ---
> ffff0000-00000000 00010000 r-x
> page layout changed following mmap
> start    end      size     prot
> 00010000-00090000 00080000 r-x
> 00090000-000a0000 00010000 rw-
> ffff0000-00000000 00010000 r-x
> page layout changed following mmap
> start    end      size     prot
> 00010000-00090000 00080000 r-x
> 00090000-000a0000 00010000 rw-
> 40000000-40810000 00810000 rw-
> ffff0000-00000000 00010000 r-x
> page layout changed following mmap
> start    end      size     prot
> 00010000-00090000 00080000 r-x
> 00090000-000a0000 00010000 rw-
> 40000000-40010000 00010000 ---
> 40010000-40811000 00801000 rw-
> ffff0000-00000000 00010000 r-x
> guest_base  0x140420000
> page layout changed following binary load
> start    end      size     prot
> 00010000-00090000 00080000 r-x
> 00090000-000a0000 00010000 rw-
> 40000000-40010000 00010000 ---
> 40010000-40810000 00800000 rw-
> 40810000-40811000 00001000 r-x
> ffff0000-00000000 00010000 r-x
> end_code    0x00084f7c
> start_code  0x00010000
> start_data  0x00095098
> end_data    0x00098394
> start_stack 0x4080f410
> brk         0x0009b000
> entry       0x00010418
> argv_start  0x4080f414
> env_start   0x4080f41c
> auxv_start  0x4080f4a0
> 143551 brk(NULL) = 0x0009b000
> 143551 brk(0x0009b8fc) = 0x0009b000

I think the problem is the brk with 9b000 here.
It's not 64k aligned (=pages size of your ppc64le).

Please try with this patch on top of Richard's series:

> @@ -3229,7 +3208,8 @@ static void load_elf_image(const char *image_name, int 
> image_fd,
>       info->end_code = 0;
>       info->start_data = -1;
>       info->end_data = 0;
> -    info->brk = .....
change that to become:
    info->brk = HOST_PAGE_ALIGN(hiaddr);

Helge