https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119210
--- Comment #4 from xiezhiheng at huawei dot com ---
(In reply to Andrew Pinski from comment #3)
> So:
> mrs x16, tpidr2_el0
> cbnz x16, .L22 <== it will branch to .L22, and miss 'smstart za'
> mov x0, x3
> smstart za
> bl __arm_tpidr2_restore
> .L22:
>
>
> This means it is already started.
>
>
> What kernel version are you using? Could this be a bug in the kernel not
> saving/restoring tpidr2_el0 correctly or setting tpidr2_el0 to zero
> originally.
In main function,
main:
stp x29, x30, [sp, -144]!
rdsvl x0, #1
cntd x16
mov x29, sp
mul x1, x0, x0
stp x23, x16, [sp, 48]
stp x19, x20, [sp, 16]
stp x21, x22, [sp, 32]
stp d8, d9, [sp, 64]
stp d10, d11, [sp, 80]
stp d12, d13, [sp, 96]
stp d14, d15, [sp, 112]
sub sp, sp, x1
mov x1, sp
stp x1, x0, [x29, 128]
mrs x0, tpidr2_el0 <== in gdb, it is zero
cbz x0, .L19
bl __arm_tpidr2_save
.L19:
add x0, x29, 128
msr tpidr2_el0, x0 <== then it writes 0xfffffffff410 to
tpidr2_el0
mov x0, 512
bl malloc
mov x1, 1
mov x20, x0
mov x0, 512
bl calloc
mov x1, 1
mov x21, x0
mov x0, 512
bl calloc
mov x22, x0
mov x0, 0
index z31.d, #0, #1
mov w1, 64
cntd x2
whilelo p6.d, wzr, w1
ptrue p7.b, all
mov z30.s, w2
.L11:
movprfx z29, z31
sxtw z29.d, p7/m, z31.d
scvtf z29.d, p7/m, z29.d
st1d z29.d, p6, [x20, x0, lsl 3]
add z31.s, z31.s, z30.s
incd x0
whilelo p6.d, w0, w1
b.any .L11
adrp x23, .LC0
add x23, x23, :lo12:.LC0
mov x19, 0
.L12:
ldr d1, [x21, x19, lsl 3]
mov w1, w19
ldr d0, [x20, x19, lsl 3]
mov x0, x23
add x19, x19, 1
bl printf
cmp x19, 64
bne .L12
mov x1, x21
add x3, x29, 128
mrs x16, tpidr2_el0 <== then it reads 0xfffffffff410 from
tpidr2_el0
cbnz x16, .L22
mov x0, x3
smstart za
bl __arm_tpidr2_restore
.L22:
adrp x23, .LC1
add x23, x23, :lo12:.LC1
msr tpidr2_el0, xzr <== here reset to zero, but seems useless
mov x19, 0
mov x0, x20
smstart sm
bl example(double*, double*)
smstop sm
mov x0, x22
smstart sm
bl example0(double*)
smstop sm
smstop za
I do not see other operations on tpidr2_el0. I am not very familiar with SME
system registers, and will somewhere reset tpidr2_el0 to zero?
