From b0c5b4f1ee3687c57dab65ac0729a4d61967f032 Mon Sep 17 00:00:00 2001 From: Rohan McLure Date: Wed, 10 May 2023 13:31:12 +1000 Subject: powerpc: powernv: Fix KCSAN datarace warnings on idle_state contention The idle_state entry in the PACA on PowerNV features a bit which is atomically tested and set through ldarx/stdcx. to be used as a spinlock. This lock then guards access to other bit fields of idle_state. KCSAN cannot differentiate between any of these bitfield accesses as they all are implemented by 8-byte store/load instructions, thus cores contending on the bit-lock appear to data race with modifications to idle_state. Separate the bit-lock entry from the data guarded by the lock to avoid the possibility of data races being detected by KCSAN. Suggested-by: Nicholas Piggin Signed-off-by: Rohan McLure Reviewed-by: Nicholas Piggin Signed-off-by: Michael Ellerman Link: https://msgid.link/20230510033117.1395895-7-rmclure@linux.ibm.com --- arch/powerpc/include/asm/paca.h | 1 + 1 file changed, 1 insertion(+) (limited to 'arch/powerpc/include/asm/paca.h') diff --git a/arch/powerpc/include/asm/paca.h b/arch/powerpc/include/asm/paca.h index da0377f46597..cb325938766a 100644 --- a/arch/powerpc/include/asm/paca.h +++ b/arch/powerpc/include/asm/paca.h @@ -191,6 +191,7 @@ struct paca_struct { #ifdef CONFIG_PPC_POWERNV /* PowerNV idle fields */ /* PNV_CORE_IDLE_* bits, all siblings work on thread 0 paca */ + unsigned long idle_lock; /* A value of 1 means acquired */ unsigned long idle_state; union { /* P7/P8 specific fields */ -- cgit v1.2.3