riscv: uaccess should be used in nommu mode
Greentime Hu authored

It might have the unaligned access exception when trying to exchange data
with user space program. In this case, it failed in tty_ioctl(). Therefore
we should enable uaccess.S for NOMMU mode since the generic code doesn't
handle the unaligned access cases.

   0x8013a212 <tty_ioctl+462>:  ld      a5,460(s1)

[    0.115279] Oops - load address misaligned [#1]
[    0.115284] CPU: 0 PID: 29 Comm: sh Not tainted 5.4.0-rc5-00020-gb4c27160d562-dirty #36
[    0.115294] epc: 000000008013a212 ra : 000000008013a212 sp : 000000008f48dd50
[    0.115303]  gp : 00000000801cac28 tp : 000000008fb80000 t0 : 00000000000000e8
[    0.115312]  t1 : 000000008f58f108 t2 : 0000000000000009 s0 : 000000008f48ddf0
[    0.115321]  s1 : 000000008f8c6220 a0 : 0000000000000001 a1 : 000000008f48dd28
[    0.115330]  a2 : 000000008fb80000 a3 : 00000000801a7398 a4 : 0000000000000000
[    0.115339]  a5 : 0000000000000000 a6 : 000000008f58f0c6 a7 : 000000000000001d
[    0.115348]  s2 : 000000008f8c6308 s3 : 000000008f78b7c8 s4 : 000000008fb834c0
[    0.115357]  s5 : 0000000000005413 s6 : 0000000000000000 s7 : 000000008f58f2b0
[    0.115366]  s8 : 000000008f858008 s9 : 000000008f776818 s10: 000000008f776830
[    0.115375]  s11: 000000008fb840a8 t3 : 1999999999999999 t4 : 000000008f78704c
[    0.115384]  t5 : 0000000000000005 t6 : 0000000000000002
[    0.115391] status: 0000000200001880 badaddr: 000000008f8c63ec cause: 0000000000000004
[    0.115401] ---[ end trace 00d490c6a8b6c9ac ]---

This failure could be fixed after this patch applied.

[    0.002282] Run /init as init process
Initializing random number generator... [    0.005573] random: dd: uninitialized urandom read (512 bytes read)
done.

Welcome to Buildroot
buildroot login: root
Password:
Jan  1 00:00:00 login[62]: root login on 'ttySIF0'
~ #
Signed-off-by: default avatarGreentime Hu <greentime.hu@sifive.com>
Reviewed-by: default avatarPalmer Dabbelt <palmerdabbelt@google.com>
Signed-off-by: default avatarPalmer Dabbelt <palmerdabbelt@google.com>
adccfb1a
Linux kernel
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