In ppc, compiler based sanitizer will generate instrument instructions
around statement WRITE_ONCE(local_paca->irq_soft_mask, mask):
0xc000000000295cb0 <+0>: addis r2,r12,774
0xc000000000295cb4 <+4>: addi r2,r2,16464
0xc000000000295cb8 <+8>: mflr r0
0xc000000000295cbc <+12>: bl 0xc00000000008bb4c <mcount>
0xc000000000295cc0 <+16>: mflr r0
0xc000000000295cc4 <+20>: std r31,-8(r1)
0xc000000000295cc8 <+24>: addi r3,r13,2354
0xc000000000295ccc <+28>: mr r31,r13
0xc000000000295cd0 <+32>: std r0,16(r1)
0xc000000000295cd4 <+36>: stdu r1,-48(r1)
0xc000000000295cd8 <+40>: bl 0xc000000000609b98 <__asan_store1+8>
0xc000000000295cdc <+44>: nop
0xc000000000295ce0 <+48>: li r9,1
0xc000000000295ce4 <+52>: stb r9,2354(r31)
0xc000000000295ce8 <+56>: addi r1,r1,48
0xc000000000295cec <+60>: ld r0,16(r1)
0xc000000000295cf0 <+64>: ld r31,-8(r1)
0xc000000000295cf4 <+68>: mtlr r0
If there is a context switch before "stb r9,2354(r31)", r31 may
not equal to r13, in such case, irq soft mask will not work.
This patch disable sanitizer in irq_soft_mask_set.
Signed-off-by: Zhouyi Zhou <zhouzho...@gmail.com>
---
Dear PPC developers
I found this bug when trying to do rcutorture tests in ppc VM of
Open Source Lab of Oregon State University following Paul E. McKenny's guidance.
console.log report following bug:
[ 346.527467][ T100] BUG: using smp_processor_id() in preemptible [00000000]
code: rcu_torture_rea/100^M
[ 346.529416][ T100] caller is rcu_preempt_deferred_qs_irqrestore+0x74/0xed0^M
[ 346.531157][ T100] CPU: 4 PID: 100 Comm: rcu_torture_rea Tainted: G
W 5.19.0-rc5-next-20220708-dirty #253^M
[ 346.533620][ T100] Call Trace:^M
[ 346.534449][ T100] [c0000000094876c0] [c000000000ce2b68]
dump_stack_lvl+0xbc/0x108 (unreliable)^M
[ 346.536632][ T100] [c000000009487710] [c000000001712954]
check_preemption_disabled+0x154/0x160^M
[ 346.538665][ T100] [c0000000094877a0] [c0000000002ce2d4]
rcu_preempt_deferred_qs_irqrestore+0x74/0xed0^M
[ 346.540830][ T100] [c0000000094878b0] [c0000000002cf3c0]
__rcu_read_unlock+0x290/0x3b0^M
[ 346.542746][ T100] [c000000009487910] [c0000000002bb330]
rcu_torture_read_unlock+0x30/0xb0^M
[ 346.544779][ T100] [c000000009487930] [c0000000002b7ff8]
rcutorture_one_extend+0x198/0x810^M
[ 346.546851][ T100] [c000000009487a10] [c0000000002b8bfc]
rcu_torture_one_read+0x58c/0xc90^M
[ 346.548844][ T100] [c000000009487ca0] [c0000000002b942c]
rcu_torture_reader+0x12c/0x360^M
[ 346.550784][ T100] [c000000009487db0] [c0000000001de978]
kthread+0x1e8/0x220^M
[ 346.552555][ T100] [c000000009487e10] [c00000000000cd54]
ret_from_kernel_thread+0x5c/0x64^M
After 12 days debugging, I finally narrow the problem to irq_soft_mask_set.
I am a beginner, hope I can be of some beneficial to the community ;-)
Thanks
Zhouyi
--
arch/powerpc/include/asm/hw_irq.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/powerpc/include/asm/hw_irq.h
b/arch/powerpc/include/asm/hw_irq.h
index 26ede09c521d..a5ae8d82cc9d 100644
--- a/arch/powerpc/include/asm/hw_irq.h
+++ b/arch/powerpc/include/asm/hw_irq.h
@@ -121,7 +121,7 @@ static inline notrace unsigned long
irq_soft_mask_return(void)
* for the critical section and as a clobber because
* we changed paca->irq_soft_mask
*/
-static inline notrace void irq_soft_mask_set(unsigned long mask)
+static inline notrace __no_kcsan __no_sanitize_address void
irq_soft_mask_set(unsigned long mask)
{
/*
* The irq mask must always include the STD bit if any are set.
--
2.34.1
