Venkat reported a panic on powerpc-next tree where GENERIC_ENTRY has
been enabled.
kernel BUG at kernel/sched/core.c:7512!
NIP preempt_schedule_irq+0x44/0x118
LR dynamic_irqentry_exit_cond_resched+0x40/0x1a4
Call Trace:
dynamic_irqentry_exit_cond_resched+0x40/0x1a4
do_page_fault+0xc0/0x104
data_access_common_virt+0x210/0x220
This happens since __do_page_fault ends up enabling the interrupts and
it could take significant time such that need_resched could be set. This
leads to schedule call in irqentry_exit leading to the bug.
There are many such irq handlers which enables the interrupts.
Fix it by disabling the irq before calling irqentry_exit. The same
pattern exists today in interrupt_exit_kernel_prepare.
Fixes: bee25f97ad ("powerpc: Enable GENERIC_ENTRY feature")
Reported-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
Closes: https://lore.kernel.org/all/7904105b-9dfa-4efd-a5ef-bc0276ed255d@linux.ibm.com/
Signed-off-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Tested-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
Reviewed-by: Mukesh Kumar Chaurasiya (IBM) <mkchauras@gmail.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260603131054.216235-1-sshegde@linux.ibm.com
Move interrupt entry and exit helper routines from interrupt.h into the
PowerPC-specific entry-common.h header as a preparatory step for enabling
the generic entry/exit framework.
This consolidation places all PowerPC interrupt entry/exit handling in a
single common header, aligning with the generic entry infrastructure.
The helpers provide architecture-specific handling for interrupt and NMI
entry/exit sequences, including:
- arch_interrupt_enter/exit_prepare()
- arch_interrupt_async_enter/exit_prepare()
- arch_interrupt_nmi_enter/exit_prepare()
- Supporting helpers such as nap_adjust_return(), check_return_regs_valid(),
debug register maintenance, and soft mask handling.
The functions are copied verbatim from interrupt.h.Subsequent patches will
integrate these routines into the generic entry/exit flow.
No functional change intended.
Signed-off-by: Mukesh Kumar Chaurasiya <mchauras@linux.ibm.com>
Tested-by: Samir M <samir@linux.ibm.com>
Tested-by: David Gow <davidgow@google.com>
Tested-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
Reviewed-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260427122742.210074-7-mkchauras@gmail.com
Add PowerPC-specific implementations of the generic syscall exit hooks
used by the generic entry/exit framework:
- arch_exit_to_user_mode_work_prepare()
- arch_exit_to_user_mode_work()
These helpers handle user state restoration when returning from the
kernel to userspace, including FPU/VMX/VSX state, transactional memory,
KUAP restore, and per-CPU accounting.
Additionally, move check_return_regs_valid() from interrupt.c to
interrupt.h so it can be shared by the new entry/exit logic.
No functional change is intended with this patch.
Signed-off-by: Mukesh Kumar Chaurasiya <mchauras@linux.ibm.com>
Tested-by: Samir M <samir@linux.ibm.com>
Tested-by: David Gow <davidgow@google.com>
Tested-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
Reviewed-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260427122742.210074-5-mkchauras@gmail.com
Implement the arch_enter_from_user_mode() hook required by the generic
entry/exit framework. This helper prepares the CPU state when entering
the kernel from userspace, ensuring correct handling of KUAP/KUEP,
transactional memory, and debug register state.
This patch contains no functional changes, it is purely preparatory for
enabling the generic syscall and interrupt entry path on PowerPC.
Signed-off-by: Mukesh Kumar Chaurasiya <mchauras@linux.ibm.com>
Tested-by: Samir M <samir@linux.ibm.com>
Tested-by: David Gow <davidgow@google.com>
Tested-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
Reviewed-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260427122742.210074-4-mkchauras@gmail.com
This patch introduces preparatory changes needed to support building
PowerPC with the generic entry/exit (irqentry) framework.
The following infrastructure updates are added:
- Add a syscall_work field to struct thread_info to hold SYSCALL_WORK_* flags.
- Provide a stub implementation of arch_syscall_is_vdso_sigreturn(),
returning false for now.
- Introduce on_thread_stack() helper to detect if the current stack pointer
lies within the task’s kernel stack.
These additions enable later integration with the generic entry/exit
infrastructure while keeping existing PowerPC behavior unchanged.
No functional change is intended in this patch.
Signed-off-by: Mukesh Kumar Chaurasiya <mchauras@linux.ibm.com>
Tested-by: Samir M <samir@linux.ibm.com>
Tested-by: David Gow <davidgow@google.com>
Tested-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
Reviewed-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260427122742.210074-3-mkchauras@gmail.com
