Commit cd01672d authored by Anton Ivanov's avatar Anton Ivanov Committed by Johannes Berg
Browse files

um: Enable preemption in UML 



Since userspace state is saved in the MM process, kernel using
FPU still doesn't really need to do anything, so this really
is as simple as enabling preemption. The irq critical section
in sigio_handler() needs preempt_disable()/preempt_enable().

Signed-off-by: default avatarAnton Ivanov <anton.ivanov@cambridgegreys.com>
Link: https://patch.msgid.link/20240702102549.d2fcea450854.I12f5a53d80ec1e425e66ef272b1e95cb523b608e@changeid


[rebase, remove FPU save/restore, fix x86/um Makefile,
 rewrite commit message]
Signed-off-by: default avatarJohannes Berg <johannes.berg@intel.com>
parent bcf3d957

arch/um/Kconfig

+1 −1
Original line number Diff line number Diff line
@@ -11,7 +11,7 @@ config UML 
	select ARCH_HAS_KCOV

	select ARCH_HAS_STRNCPY_FROM_USER

	select ARCH_HAS_STRNLEN_USER

	select ARCH_NO_PREEMPT

	select ARCH_NO_PREEMPT_DYNAMIC

	select HAVE_ARCH_AUDITSYSCALL

	select HAVE_ARCH_KASAN if X86_64

	select HAVE_ARCH_KASAN_VMALLOC if HAVE_ARCH_KASAN

arch/um/kernel/irq.c

+2 −0
Original line number Diff line number Diff line
@@ -238,7 +238,9 @@ static void _sigio_handler(struct uml_pt_regs *regs, 


void sigio_handler(int sig, struct siginfo *unused_si, struct uml_pt_regs *regs)

{

	preempt_disable();

	_sigio_handler(regs, irqs_suspended);

	preempt_enable();

}



static struct irq_entry *get_irq_entry_by_fd(int fd)

arch/x86/um/Makefile

+0 −1
Original line number Diff line number Diff line
@@ -31,7 +31,6 @@ obj-y += syscalls_64.o vdso/ 


subarch-y = ../lib/csum-partial_64.o ../lib/memcpy_64.o \

	../lib/memmove_64.o ../lib/memset_64.o

subarch-$(CONFIG_PREEMPTION) += ../entry/thunk_64.o



endif