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linux/arch/riscv/kernel/vdso
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Guo Ren e05d57dcb8
riscv: Fixup __vdso_gettimeofday broke dynamic ftrace 
For linux-5.8-rc1, enable ftrace of riscv will cause boot panic:

[    2.388980] Run /sbin/init as init process
[    2.529938] init[39]: unhandled signal 4 code 0x1 at 0x0000003ff449e000
[    2.531078] CPU: 0 PID: 39 Comm: init Not tainted 5.8.0-rc1-dirty #13
[    2.532719] epc: 0000003ff449e000 ra : 0000003ff449e954 sp : 0000003fffedb900
[    2.534005]  gp : 00000000000e8528 tp : 0000003ff449d800 t0 : 000000000000001e
[    2.534965]  t1 : 000000000000000a t2 : 0000003fffedb89e s0 : 0000003fffedb920
[    2.536279]  s1 : 0000003fffedb940 a0 : 0000003ff43d4b2c a1 : 0000000000000000
[    2.537334]  a2 : 0000000000000001 a3 : 0000000000000000 a4 : fffffffffbad8000
[    2.538466]  a5 : 0000003ff449e93a a6 : 0000000000000000 a7 : 0000000000000000
[    2.539511]  s2 : 0000000000000000 s3 : 0000003ff448412c s4 : 0000000000000010
[    2.541260]  s5 : 0000000000000016 s6 : 00000000000d0a30 s7 : 0000003fffedba70
[    2.542152]  s8 : 0000000000000000 s9 : 0000000000000000 s10: 0000003fffedb960
[    2.543335]  s11: 0000000000000000 t3 : 0000000000000000 t4 : 0000003fffedb8a0
[    2.544471]  t5 : 0000000000000000 t6 : 0000000000000000
[    2.545730] status: 0000000000004020 badaddr: 00000000464c457f cause: 0000000000000002
[    2.549867] Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000004
[    2.551267] CPU: 0 PID: 1 Comm: init Not tainted 5.8.0-rc1-dirty #13
[    2.552061] Call Trace:
[    2.552626] [<ffffffe00020374a>] walk_stackframe+0x0/0xc4
[    2.553486] [<ffffffe0002039f4>] show_stack+0x40/0x4c
[    2.553995] [<ffffffe00054a6ae>] dump_stack+0x7a/0x98
[    2.554615] [<ffffffe00020b9b8>] panic+0x114/0x2f4
[    2.555395] [<ffffffe00020ebd6>] do_exit+0x89c/0x8c2
[    2.555949] [<ffffffe00020f930>] do_group_exit+0x3a/0x90
[    2.556715] [<ffffffe000219e08>] get_signal+0xe2/0x6e6
[    2.557388] [<ffffffe000202d72>] do_notify_resume+0x6a/0x37a
[    2.558089] [<ffffffe000201c16>] ret_from_exception+0x0/0xc

"ra:0x3ff449e954" is the return address of "call _mcount" in the
prologue of __vdso_gettimeofday(). Without proper relocate, pc jmp
to 0x0000003ff449e000 (vdso map base) with a illegal instruction
trap.

The solution comes from arch/arm64/kernel/vdso/Makefile:

CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE) -Os $(CC_FLAGS_SCS)

 - CC_FLAGS_SCS is ShadowCallStack feature in Clang and only
   implemented for arm64, no use for riscv.

Fixes: ad5d1122b8 ("riscv: use vDSO common flow to reduce the latency of the time-related functions")
Cc: stable@vger.kernel.org
Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Reviewed-by: Vincent Chen <vincent.chen@sifive.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
 		2020-06-25 15:38:39 -07:00
..
.gitignore .gitignore: add SPDX License Identifier 2020-03-25 11:50:48 +01:00
Makefile riscv: Fixup __vdso_gettimeofday broke dynamic ftrace 2020-06-25 15:38:39 -07:00
flush_icache.S treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 286 2019-06-05 17:36:37 +02:00
getcpu.S treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 286 2019-06-05 17:36:37 +02:00
note.S riscv: add Linux note to vdso 2020-05-04 14:22:34 -07:00
rt_sigreturn.S treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 286 2019-06-05 17:36:37 +02:00
vdso.S treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 286 2019-06-05 17:36:37 +02:00
vdso.lds.S riscv: use vDSO common flow to reduce the latency of the time-related functions 2020-06-10 19:47:16 -07:00
vgettimeofday.c riscv: Add extern declarations for vDSO time-related functions 2020-06-25 15:15:51 -07:00