lwn.git/arch/openrisc/kernel/signal.c, branch docs-fixes

openrisc: Add support for restartable sequences

2025-01-14T17:17:16+00:00

Implement support for restartable sequences on OpenRISC by doing: - Select HAVE_RSEQ in Kconfig - Call rseq_syscall() on return to userspace when CONFIG_DEBUG_RSEQ is enabled. - Call rseq_signal_deliver() to fixup the pre-signal stack frame when a signal is delivered on top of a restartable sequence critical section Cc: Michael Jeanson Signed-off-by: Stafford Horne

openrisc: Move FPU state out of pt_regs

2024-04-15T14:20:39+00:00

My original, naive, FPU support patch had the FPCSR register stored during both the *mode switch* and *context switch*. This is wasteful. Also, the original patches did not save the FPU state when handling signals during the system call fast path. We fix this by moving the FPCSR state to thread_struct in task_struct. We also introduce new helper functions save_fpu and restore_fpu which can be used to sync the FPU with thread_struct. These functions are now called when needed: - Setting up and restoring sigcontext when handling signals - Before and after __switch_to during context switches - When handling FPU exceptions - When reading and writing FPU register sets In the future we can further optimize this by doing lazy FPU save and restore. For example, FPU sync is not needed when switching to and from kernel threads (x86 does this). FPU save and restore does not need to be done two times if we have both rescheduling and signal work to do. However, since OpenRISC FPU state is a single register, I leave these optimizations for future consideration. Signed-off-by: Stafford Horne

openrisc: Declare do_signal function as static

2023-08-21T07:12:11+00:00

When compiling with W=1 enabling -Wmissing-prototypes the compiler warns: arch/openrisc/kernel/signal.c:227:5: error: no previous prototype for 'do_signal' [-Werror=missing-prototypes] Fix this by declaring the function a static as it is not used outside of the scope of this file. Reported-by: Arnd Bergmann Closes: https://lore.kernel.org/linux-kernel/20230810141947.1236730-17-arnd@kernel.org/ Signed-off-by: Stafford Horne

openrisc: Add missing prototypes for assembly called fnctions

2023-08-21T07:11:54+00:00

These functions are all called from assembly files so there is no need for a prototype in a header file, but when compiling with W=1 enabling -Wmissing-prototypes the compiler warns: arch/openrisc/kernel/ptrace.c:191:17: error: no previous prototype for 'do_syscall_trace_enter' [-Werror=missing-prototypes] arch/openrisc/kernel/ptrace.c:210:17: error: no previous prototype for 'do_syscall_trace_leave' [-Werror=missing-prototypes] arch/openrisc/kernel/signal.c:293:1: error: no previous prototype for 'do_work_pending' [-Werror=missing-prototypes] arch/openrisc/kernel/signal.c:68:17: error: no previous prototype for '_sys_rt_sigreturn' [-Werror=missing-prototypes] arch/openrisc/kernel/time.c:111:25: error: no previous prototype for 'timer_interrupt' [-Werror=missing-prototypes] arch/openrisc/kernel/traps.c:239:17: error: no previous prototype for 'unhandled_exception' [-Werror=missing-prototypes] arch/openrisc/kernel/traps.c:246:17: error: no previous prototype for 'do_fpe_trap' [-Werror=missing-prototypes] arch/openrisc/kernel/traps.c:268:17: error: no previous prototype for 'do_trap' [-Werror=missing-prototypes] arch/openrisc/kernel/traps.c:273:17: error: no previous prototype for 'do_unaligned_access' [-Werror=missing-prototypes] arch/openrisc/kernel/traps.c:286:17: error: no previous prototype for 'do_bus_fault' [-Werror=missing-prototypes] arch/openrisc/kernel/traps.c:462:17: error: no previous prototype for 'do_illegal_instruction' [-Werror=missing-prototypes] arch/openrisc/mm/fault.c:44:17: error: no previous prototype for 'do_page_fault' [-Werror=missing-prototypes] Since these are not needed in header files, fix these by adding prototypes to the top of the respective C files. Reported-by: Arnd Bergmann Closes: https://lore.kernel.org/linux-kernel/20230810141947.1236730-17-arnd@kernel.org/ Signed-off-by: Stafford Horne

openrisc: Union fpcsr and oldmask in sigcontext to unbreak userspace ABI

2023-07-10T21:03:26+00:00

With commit 27267655c531 ("openrisc: Support floating point user api") I added an entry to the struct sigcontext which caused an unwanted change to the userspace ABI. To fix this we use the previously unused oldmask field space for the floating point fpcsr state. We do this with a union to restore the ABI back to the pre kernel v6.4 ABI and keep API compatibility. This does mean if there is some code somewhere that is setting oldmask in an OpenRISC specific userspace sighandler it would end up setting the floating point register status, but I think it's unlikely as oldmask was never functional before. Fixes: 27267655c531 ("openrisc: Support floating point user api") Reported-by: Szabolcs Nagy Closes: https://lore.kernel.org/openrisc/20230626213840.GA1236108@port70.net/ Signed-off-by: Stafford Horne

openrisc: Support floating point user api

2023-04-26T14:08:06+00:00

Add support for handling floating point exceptions and forwarding the SIGFPE signal to processes. Also, add fpu state to sigcontext. Signed-off-by: Stafford Horne

resume_user_mode: Move to resume_user_mode.h

2022-03-10T22:51:50+00:00

Move set_notify_resume and tracehook_notify_resume into resume_user_mode.h. While doing that rename tracehook_notify_resume to resume_user_mode_work. Update all of the places that included tracehook.h for these functions to include resume_user_mode.h instead. Update all of the callers of tracehook_notify_resume to call resume_user_mode_work. Reviewed-by: Kees Cook Link: https://lkml.kernel.org/r/20220309162454.123006-12-ebiederm@xmission.com Signed-off-by: "Eric W. Biederman"

openrisc: Snapshot thread flags

2021-11-30T23:06:44+00:00

Some thread flags can be set remotely, and so even when IRQs are disabled, the flags can change under our feet. Generally this is unlikely to cause a problem in practice, but it is somewhat unsound, and KCSAN will legitimately warn that there is a data race. To avoid such issues, a snapshot of the flags has to be taken prior to using them. Some places already use READ_ONCE() for that, others do not. Convert them all to the new flag accessor helpers. Signed-off-by: Mark Rutland Signed-off-by: Thomas Gleixner Acked-by: Stafford Horne Acked-by: Paul E. McKenney Cc: Jonas Bonn Cc: Stefan Kristiansson Link: https://lore.kernel.org/r/20211129130653.2037928-9-mark.rutland@arm.com

openrisc: signal: remove unused DEBUG_SIG macro

2021-10-20T20:42:06+00:00

Signed-off-by: Denis Kirjanov Signed-off-by: Stafford Horne

openrisc: add support for TIF_NOTIFY_SIGNAL

2020-11-09T15:16:55+00:00

Wire up TIF_NOTIFY_SIGNAL handling for openrisc. Cc: openrisc@lists.librecores.org Acked-by: Stafford Horne Signed-off-by: Jens Axboe