[PATCH V9 20/20] riscv: compat: Add COMPAT Kbuild skeletal support

[Guo Ren]

On Mon, May 23, 2022 at 1:45 PM Guenter Roeck <linux at roeck-us.net> wrote:
>
> On Tue, Mar 22, 2022 at 10:40:03PM +0800, guoren at kernel.org wrote:
> > From: Guo Ren <guoren at linux.alibaba.com>
> >
> > Adds initial skeletal COMPAT Kbuild (Running 32bit U-mode on
> > 64bit S-mode) support.
> >  - Setup kconfig & dummy functions for compiling.
> >  - Implement compat_start_thread by the way.
> >
> > Signed-off-by: Guo Ren <guoren at linux.alibaba.com>
> > Signed-off-by: Guo Ren <guoren at kernel.org>
> > Reviewed-by: Arnd Bergmann <arnd at arndb.de>
> > Tested-by: Heiko Stuebner <heiko at sntech.de>
> > Cc: Palmer Dabbelt <palmer at dabbelt.com>
>
> With this patch in linux-next, all my riscv64 emulations crash.
>
> [   11.600082] Run /sbin/init as init process
> [   11.628561] init[1]: unhandled signal 11 code 0x1 at 0x0000000000000000 in libc.so[ffffff8ad39000+a4000]
> [   11.629398] CPU: 0 PID: 1 Comm: init Not tainted 5.18.0-rc7-next-20220520 #1
> [   11.629462] Hardware name: riscv-virtio,qemu (DT)
> [   11.629546] epc : 00ffffff8ada1100 ra : 00ffffff8ada13c8 sp : 00ffffffc58199f0
> [   11.629586]  gp : 00ffffff8ad39000 tp : 00ffffff8ade0998 t0 : ffffffffffffffff
> [   11.629598]  t1 : 00ffffffc5819fd0 t2 : 0000000000000000 s0 : 00ffffff8ade0cc0
> [   11.629610]  s1 : 00ffffff8ade0cc0 a0 : 0000000000000000 a1 : 00ffffffc5819a00
> [   11.629622]  a2 : 0000000000000001 a3 : 000000000000001e a4 : 00ffffffc5819b00
> [   11.629634]  a5 : 00ffffffc5819b00 a6 : 0000000000000000 a7 : 0000000000000000
> [   11.629645]  s2 : 00ffffff8ade0ac8 s3 : 00ffffff8ade0ec8 s4 : 00ffffff8ade0728
> [   11.629656]  s5 : 00ffffff8ade0a90 s6 : 0000000000000000 s7 : 00ffffffc5819e40
> [   11.629667]  s8 : 00ffffff8ade0ca0 s9 : 00ffffff8addba50 s10: 0000000000000000
> [   11.629678]  s11: 0000000000000000 t3 : 0000000000000002 t4 : 0000000000000001
> [   11.629688]  t5 : 0000000000020000 t6 : ffffffffffffffff
> [   11.629699] status: 0000000000004020 badaddr: 0000000000000000 cause: 000000000000000d
> [   11.633421] Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b
> [   11.633664] CPU: 0 PID: 1 Comm: init Not tainted 5.18.0-rc7-next-20220520 #1
> [   11.633784] Hardware name: riscv-virtio,qemu (DT)
> [   11.633881] Call Trace:
> [   11.633960] [<ffffffff80005e72>] dump_backtrace+0x1c/0x24
> [   11.634162] [<ffffffff809aa9ec>] show_stack+0x2c/0x38
> [   11.634274] [<ffffffff809b8482>] dump_stack_lvl+0x60/0x8e
> [   11.634386] [<ffffffff809b84c4>] dump_stack+0x14/0x1c
> [   11.634491] [<ffffffff809aaca0>] panic+0x116/0x2e2
> [   11.634596] [<ffffffff80015540>] do_exit+0x7ce/0x7d4
> [   11.634707] [<ffffffff80015666>] do_group_exit+0x24/0x7c
> [   11.634817] [<ffffffff80022294>] get_signal+0x7ee/0x830
> [   11.634924] [<ffffffff800051c0>] do_notify_resume+0x6c/0x41c
> [   11.635037] [<ffffffff80003ad4>] ret_from_exception+0x0/0x10
The problem is come from "__dls3's vdso decode part in musl's
ldso/dynlink.c". The ehdr->e_phnum & ehdr->e_phentsize are wrong.

I think the root cause is from musl's implementation with the wrong
elf parser. I would fix that soon.

If you CONFIG_COMPAT=n, the bug would be bypassed.

>
> Guenter
>
> ---
> # bad: [18ecd30af1a8402c162cca1bd58771c0e5be7815] Add linux-next specific files for 20220520
> # good: [42226c989789d8da4af1de0c31070c96726d990c] Linux 5.18-rc7
> git bisect start 'HEAD' 'v5.18-rc7'
> # bad: [f9b63740b666dd9887eb0282d21b5f65bb0cadd0] Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/cryptodev-2.6.git
> git bisect bad f9b63740b666dd9887eb0282d21b5f65bb0cadd0
> # bad: [7db97132097c5973ff77466d0ee681650af653de] Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/cel/linux
> git bisect bad 7db97132097c5973ff77466d0ee681650af653de
> # good: [2b7d17d4b7c1ff40f58b0d32be40fc0bb6c582fb] soc: document merges
> git bisect good 2b7d17d4b7c1ff40f58b0d32be40fc0bb6c582fb
> # good: [69c9668f853fdd409bb8abbb37d615785510b29a] Merge branch 'clk-next' of git://git.kernel.org/pub/scm/linux/kernel/git/clk/linux.git
> git bisect good 69c9668f853fdd409bb8abbb37d615785510b29a
> # bad: [1577f290aa0d4c5b29c03c46ef52e4952a21bfbb] Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux.git
> git bisect bad 1577f290aa0d4c5b29c03c46ef52e4952a21bfbb
> # good: [34f0971f8ca73d7e5502b4cf299788a9402120f7] powerpc/powernv/flash: Check OPAL flash calls exist before using
> git bisect good 34f0971f8ca73d7e5502b4cf299788a9402120f7
> # good: [0349d7dfc70a26b3facd8ca97de34980d4b60954] Merge branch 'mips-next' of git://git.kernel.org/pub/scm/linux/kernel/git/mips/linux.git
> git bisect good 0349d7dfc70a26b3facd8ca97de34980d4b60954
> # bad: [20bfb54d3b121699674c17a854c5ebc7a8f97d81] Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux.git
> git bisect bad 20bfb54d3b121699674c17a854c5ebc7a8f97d81
> # bad: [9be8459298eadb39b9fe9974b890239e9c123107] riscv: compat: Add COMPAT Kbuild skeletal support
> git bisect bad 9be8459298eadb39b9fe9974b890239e9c123107
> # good: [01abdfeac81b5f56062d0a78f2cdc805db937a75] riscv: compat: Support TASK_SIZE for compat mode
> git bisect good 01abdfeac81b5f56062d0a78f2cdc805db937a75
> # good: [f4b395e6f1a588ed6c9a30474e58cf6b27b65783] riscv: compat: Add hw capability check for elf
> git bisect good f4b395e6f1a588ed6c9a30474e58cf6b27b65783
> # good: [3092eb45637573c5e435fbf5eaf9516316e5f9c6] riscv: compat: vdso: Add setup additional pages implementation
> git bisect good 3092eb45637573c5e435fbf5eaf9516316e5f9c6
> # good: [4608c159594fb40a5101357d4f614fdde9ce1fdb] riscv: compat: ptrace: Add compat_arch_ptrace implement
> git bisect good 4608c159594fb40a5101357d4f614fdde9ce1fdb
> # first bad commit: [9be8459298eadb39b9fe9974b890239e9c123107] riscv: compat: Add COMPAT Kbuild skeletal support



-- 
Best Regards
 Guo Ren

ML: https://lore.kernel.org/linux-csky/