[PATCH 0/3] Fix preemption errors in watchpoints

[Benjamin Gray]

On 29/8/23 4:34 pm, Benjamin Gray wrote:
> When enabling debug config options relating to preemption, several bugs
> appear in the kernel log. With this series applied, the breakpoint code
> no longer prints bugs when running the powerpc/ptrace selftests.
> 
> Benjamin Gray (3):
>    powerpc/watchpoints: Disable preemption in thread_change_pc()
>    powerpc/watchpoint: Disable pagefaults when getting user instruction
>    powerpc/watchpoints: Annotate atomic context in more places
> 
>   arch/powerpc/kernel/hw_breakpoint.c             | 16 +++++++++++++++-
>   arch/powerpc/kernel/hw_breakpoint_constraints.c |  7 ++++++-
>   2 files changed, 21 insertions(+), 2 deletions(-)
> 
> --
> 2.41.0

The particular config is below, used by appending to a 
ppc64le_guest_defconfig. Not all options are relevant. Tested on a 
Power8 and Power10 machine (1 and 2 watchpoints).

CONFIG_LOCALVERSION="-watchpoint-sleep"
CONFIG_GENERIC_IRQ_DEBUGFS=y
CONFIG_PREEMPT=y
CONFIG_PRINTK_INDEX=y
CONFIG_CGROUP_DEBUG=y
CONFIG_PPC_KUAP_DEBUG=y
CONFIG_SCOM_DEBUGFS=y
CONFIG_UDBG_RTAS_CONSOLE=y
CONFIG_RELOCATABLE_TEST=y
CONFIG_PM_DEBUG=y
CONFIG_PM_ADVANCED_DEBUG=y
CONFIG_STATIC_KEYS_SELFTEST=y
CONFIG_MODULE_DEBUG=y
CONFIG_MODULE_STATS=y
CONFIG_MODULE_DEBUG_AUTOLOAD_DUPS_TRACE=y
CONFIG_CMA_DEBUGFS=y
CONFIG_CMA_SYSFS=y
CONFIG_PERCPU_STATS=y
CONFIG_USERFAULTFD=y
CONFIG_VALIDATE_FS_PARSER=y
CONFIG_EXT4_DEBUG=y
CONFIG_HARDENED_USERCOPY=y
CONFIG_FORTIFY_SOURCE=y
CONFIG_DYNAMIC_DEBUG=y
CONFIG_DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT=y
CONFIG_DEBUG_INFO_SPLIT=y
CONFIG_GDB_SCRIPTS=y
CONFIG_READABLE_ASM=y
CONFIG_NET_DEV_REFCNT_TRACKER=y
CONFIG_NET_NS_REFCNT_TRACKER=y
CONFIG_DEBUG_NET=y
CONFIG_DEBUG_PAGEALLOC=y
CONFIG_SLUB_DEBUG_ON=y
CONFIG_PTDUMP_DEBUGFS=y
CONFIG_DEBUG_KMEMLEAK=y
CONFIG_PER_VMA_LOCK_STATS=y
CONFIG_DEBUG_OBJECTS=y
CONFIG_DEBUG_OBJECTS_SELFTEST=y
CONFIG_DEBUG_OBJECTS_FREE=y
CONFIG_DEBUG_OBJECTS_TIMERS=y
CONFIG_DEBUG_OBJECTS_WORK=y
CONFIG_DEBUG_OBJECTS_RCU_HEAD=y
CONFIG_DEBUG_OBJECTS_PERCPU_COUNTER=y
CONFIG_SHRINKER_DEBUG=y
CONFIG_SCHED_STACK_END_CHECK=y
CONFIG_DEBUG_VM=y
CONFIG_DEBUG_VM_MAPLE_TREE=y
CONFIG_DEBUG_VM_RB=y
CONFIG_DEBUG_VM_PGFLAGS=y
CONFIG_DEBUG_VM_PGTABLE=y
CONFIG_DEBUG_VIRTUAL=y
CONFIG_DEBUG_PER_CPU_MAPS=y
CONFIG_DEBUG_SHIRQ=y
CONFIG_WQ_WATCHDOG=y
CONFIG_DEBUG_TIMEKEEPING=y
CONFIG_DEBUG_PREEMPT=y
CONFIG_PROVE_LOCKING=y
CONFIG_LOCK_STAT=y
CONFIG_DEBUG_ATOMIC_SLEEP=y
CONFIG_DEBUG_LOCKING_API_SELFTESTS=y
CONFIG_CSD_LOCK_WAIT_DEBUG=y
CONFIG_DEBUG_IRQFLAGS=y
CONFIG_WARN_ALL_UNSEEDED_RANDOM=y
CONFIG_DEBUG_NOTIFIERS=y
CONFIG_DEBUG_CREDENTIALS=y
CONFIG_RCU_CPU_STALL_CPUTIME=y
CONFIG_RCU_EQS_DEBUG=y
CONFIG_DEBUG_WQ_FORCE_RR_CPU=y
CONFIG_CPU_HOTPLUG_STATE_CONTROL=y
CONFIG_LATENCYTOP=y
CONFIG_PPC_IRQ_SOFT_MASK_DEBUG=y
CONFIG_PPC_RFI_SRR_DEBUG=y