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cpu_exit() diet
> Date: Fri, 16 May 2025 16:31:23 +0200
> From: Martin Pieuchot <mpi@grenadille.net>
>
> Diff below moves pmap_deactivate() and sched_exit() outside of
> cpu_exit().
>
> The order of operations change for i386 and mips64:
>
> - For i386 pmap_deactivate() was missing but since it's a no-op it's fine.
>
> - For mips64 pmap_deactivate() was called before restoring `p_addr'. It's
> also harmless because it only clears the curpmap pointer.
I came to the same conclusion.
> I tested this on arm64, amd64 and i386. I'd appreciate tests on other
> architectures to ensure there's no mistake.
Add armv7 and powerpc64 to that list.
> ok?
ok kettenis@
> Index: kern/kern_exit.c
> ===================================================================
> RCS file: /cvs/src/sys/kern/kern_exit.c,v
> diff -u -p -r1.246 kern_exit.c
> --- kern/kern_exit.c 16 May 2025 13:40:30 -0000 1.246
> +++ kern/kern_exit.c 16 May 2025 14:13:41 -0000
> @@ -382,16 +382,21 @@ exit1(struct proc *p, int xexit, int xsi
> */
>
> /*
> - * Finally, call machine-dependent code to switch to a new
> - * context (possibly the idle context). Once we are no longer
> - * using the dead process's vmspace and stack, exit2() will be
> - * called to schedule those resources to be released by the
> - * reaper thread.
> - *
> - * Note that cpu_exit() will end with a call equivalent to
> - * cpu_switch(), finishing our execution (pun intended).
> + * Finally, call machine-dependent code.
> */
> cpu_exit(p);
> +
> + /*
> + * Deactivate the exiting address space before the vmspace
> + * is freed. Note that we will continue to run on this
> + * vmspace's context until the switch to idle in sched_exit().
> + *
> + * Once we are no longer using the dead process's vmspace and
> + * stack, exit2() will be called to schedule those resources
> + * to be released by the reaper thread.
> + */
> + pmap_deactivate(p);
> + sched_exit(p);
> panic("cpu_exit returned");
> }
>
> Index: arch/alpha/alpha/locore.s
> ===================================================================
> RCS file: /cvs/src/sys/arch/alpha/alpha/locore.s,v
> diff -u -p -r1.57 locore.s
> --- arch/alpha/alpha/locore.s 28 Apr 2025 13:27:20 -0000 1.57
> +++ arch/alpha/alpha/locore.s 16 May 2025 14:13:41 -0000
> @@ -653,7 +653,7 @@ LEAF(cpu_switchto, 2)
> * We don't deactivate if we came here from sched_exit
> * (old pmap no longer exists; vmspace has been freed).
> * oldproc will be NULL in this case. We have actually
> - * taken care of calling pmap_deactivate() in cpu_exit(),
> + * taken care of calling pmap_deactivate() in exit1(),
> * before the vmspace went away.
> */
> beq s0, 2f
> Index: arch/alpha/alpha/vm_machdep.c
> ===================================================================
> RCS file: /cvs/src/sys/arch/alpha/alpha/vm_machdep.c,v
> diff -u -p -r1.53 vm_machdep.c
> --- arch/alpha/alpha/vm_machdep.c 21 May 2024 23:16:06 -0000 1.53
> +++ arch/alpha/alpha/vm_machdep.c 16 May 2025 14:13:41 -0000
> @@ -45,25 +45,11 @@
> #include <machine/reg.h>
>
>
> -/*
> - * cpu_exit is called as the last action during exit.
> - */
> void
> -cpu_exit(p)
> - struct proc *p;
> +cpu_exit(struct proc *p)
> {
> -
> if (p->p_addr->u_pcb.pcb_fpcpu != NULL)
> fpusave_proc(p, 0);
> -
> - /*
> - * Deactivate the exiting address space before the vmspace
> - * is freed. Note that we will continue to run on this
> - * vmspace's context until the switch to idle in sched_exit().
> - */
> - pmap_deactivate(p);
> - sched_exit(p);
> - /* NOTREACHED */
> }
>
> /*
> Index: arch/amd64/amd64/vm_machdep.c
> ===================================================================
> RCS file: /cvs/src/sys/arch/amd64/amd64/vm_machdep.c,v
> diff -u -p -r1.49 vm_machdep.c
> --- arch/amd64/amd64/vm_machdep.c 24 Oct 2024 17:37:03 -0000 1.49
> +++ arch/amd64/amd64/vm_machdep.c 16 May 2025 14:13:41 -0000
> @@ -116,17 +116,9 @@ cpu_fork(struct proc *p1, struct proc *p
> pcb->pcb_rbp = 0;
> }
>
> -/*
> - * cpu_exit is called as the last action during exit.
> - *
> - * We clean up a little and then call sched_exit() with the old proc as an
> - * argument.
> - */
> void
> cpu_exit(struct proc *p)
> {
> - pmap_deactivate(p);
> - sched_exit(p);
> }
>
> /*
> Index: arch/arm/arm/vm_machdep.c
> ===================================================================
> RCS file: /cvs/src/sys/arch/arm/arm/vm_machdep.c,v
> diff -u -p -r1.29 vm_machdep.c
> --- arch/arm/arm/vm_machdep.c 11 Apr 2023 00:45:07 -0000 1.29
> +++ arch/arm/arm/vm_machdep.c 16 May 2025 14:13:41 -0000
> @@ -130,9 +130,6 @@ cpu_exit(struct proc *p)
> /* If we were using the FPU, forget about it. */
> if (p->p_addr->u_pcb.pcb_fpcpu != NULL)
> vfp_discard(p);
> -
> - pmap_deactivate(p);
> - sched_exit(p);
> }
>
> struct kmem_va_mode kv_physwait = {
> Index: arch/arm64/arm64/vm_machdep.c
> ===================================================================
> RCS file: /cvs/src/sys/arch/arm64/arm64/vm_machdep.c,v
> diff -u -p -r1.13 vm_machdep.c
> --- arch/arm64/arm64/vm_machdep.c 31 Jan 2025 20:49:25 -0000 1.13
> +++ arch/arm64/arm64/vm_machdep.c 16 May 2025 14:13:41 -0000
> @@ -112,17 +112,9 @@ cpu_fork(struct proc *p1, struct proc *p
> pcb->pcb_sp = (uint64_t)sf;
> }
>
> -/*
> - * cpu_exit is called as the last action during exit.
> - *
> - * We clean up a little and then call sched_exit() with the old proc as an
> - * argument.
> - */
> void
> cpu_exit(struct proc *p)
> {
> - pmap_deactivate(p);
> - sched_exit(p);
> }
>
> struct kmem_va_mode kv_physwait = {
> Index: arch/hppa/hppa/vm_machdep.c
> ===================================================================
> RCS file: /cvs/src/sys/arch/hppa/hppa/vm_machdep.c,v
> diff -u -p -r1.85 vm_machdep.c
> --- arch/hppa/hppa/vm_machdep.c 25 Oct 2022 15:15:38 -0000 1.85
> +++ arch/hppa/hppa/vm_machdep.c 16 May 2025 14:13:41 -0000
> @@ -131,9 +131,6 @@ cpu_exit(struct proc *p)
> fpu_proc_flush(p);
>
> pool_put(&hppa_fppl, pcb->pcb_fpstate);
> -
> - pmap_deactivate(p);
> - sched_exit(p);
> }
>
> struct kmem_va_mode kv_physwait = {
> Index: arch/i386/i386/vm_machdep.c
> ===================================================================
> RCS file: /cvs/src/sys/arch/i386/i386/vm_machdep.c,v
> diff -u -p -r1.74 vm_machdep.c
> --- arch/i386/i386/vm_machdep.c 11 Apr 2023 00:45:07 -0000 1.74
> +++ arch/i386/i386/vm_machdep.c 16 May 2025 14:13:41 -0000
> @@ -103,9 +103,6 @@ cpu_fork(struct proc *p1, struct proc *p
> pcb->pcb_ebp = 0;
> }
>
> -/*
> - * cpu_exit is called as the last action during exit.
> - */
> void
> cpu_exit(struct proc *p)
> {
> @@ -114,7 +111,6 @@ cpu_exit(struct proc *p)
> if (p->p_addr->u_pcb.pcb_fpcpu != NULL)
> npxsave_proc(p, 0);
> #endif
> - sched_exit(p);
> }
>
> /*
> Index: arch/m88k/m88k/vm_machdep.c
> ===================================================================
> RCS file: /cvs/src/sys/arch/m88k/m88k/vm_machdep.c,v
> diff -u -p -r1.30 vm_machdep.c
> --- arch/m88k/m88k/vm_machdep.c 5 Jun 2024 19:22:04 -0000 1.30
> +++ arch/m88k/m88k/vm_machdep.c 16 May 2025 14:13:41 -0000
> @@ -108,14 +108,9 @@ cpu_fork(struct proc *p1, struct proc *p
> mdpcb->pcb_pc = (u_int)proc_trampoline;
> }
>
> -/*
> - * cpu_exit is called as the last action during exit.
> - */
> void
> cpu_exit(struct proc *p)
> {
> - pmap_deactivate(p);
> - sched_exit(p);
> }
>
> struct kmem_va_mode kv_physwait = {
> Index: arch/mips64/mips64/vm_machdep.c
> ===================================================================
> RCS file: /cvs/src/sys/arch/mips64/mips64/vm_machdep.c,v
> diff -u -p -r1.42 vm_machdep.c
> --- arch/mips64/mips64/vm_machdep.c 22 May 2022 16:54:17 -0000 1.42
> +++ arch/mips64/mips64/vm_machdep.c 16 May 2025 14:13:41 -0000
> @@ -125,9 +125,6 @@ cpu_fork(struct proc *p1, struct proc *p
> pcb->pcb_context.val[0] = (register_t)func;
> }
>
> -/*
> - * cpu_exit is called as the last action during exit.
> - */
> void
> cpu_exit(struct proc *p)
> {
> @@ -136,12 +133,10 @@ cpu_exit(struct proc *p)
> if (ci->ci_fpuproc == p)
> ci->ci_fpuproc = NULL;
>
> - pmap_deactivate(p);
> #if UPAGES == 1
> /* restore p_addr for proper deallocation */
> p->p_addr = (void *)p->p_md.md_uarea;
> #endif
> - sched_exit(p);
> }
>
> struct kmem_va_mode kv_physwait = {
> Index: arch/powerpc/powerpc/vm_machdep.c
> ===================================================================
> RCS file: /cvs/src/sys/arch/powerpc/powerpc/vm_machdep.c,v
> diff -u -p -r1.55 vm_machdep.c
> --- arch/powerpc/powerpc/vm_machdep.c 11 Apr 2023 00:45:07 -0000 1.55
> +++ arch/powerpc/powerpc/vm_machdep.c 16 May 2025 14:13:41 -0000
> @@ -130,10 +130,6 @@ cpu_fork(struct proc *p1, struct proc *p
> }
>
> /*
> - * cpu_exit is called as the last action during exit.
> - * We release the address space and machine-dependent resources,
> - * including the memory for the user structure and kernel stack.
> - *
> * Since we don't have curproc anymore, we cannot sleep, and therefore
> * this is at least incorrect for the multiprocessor version.
> * Not sure whether we can get away with this in the single proc version. XXX
> @@ -157,9 +153,6 @@ cpu_exit(struct proc *p)
> if (pcb->pcb_vr != NULL)
> pool_put(&ppc_vecpl, pcb->pcb_vr);
> #endif /* ALTIVEC */
> -
> - pmap_deactivate(p);
> - sched_exit(p);
> }
>
> struct kmem_va_mode kv_physwait = {
> Index: arch/powerpc64/powerpc64/vm_machdep.c
> ===================================================================
> RCS file: /cvs/src/sys/arch/powerpc64/powerpc64/vm_machdep.c,v
> diff -u -p -r1.9 vm_machdep.c
> --- arch/powerpc64/powerpc64/vm_machdep.c 11 Apr 2023 00:45:08 -0000 1.9
> +++ arch/powerpc64/powerpc64/vm_machdep.c 16 May 2025 14:13:41 -0000
> @@ -113,17 +113,9 @@ cpu_fork(struct proc *p1, struct proc *p
> pcb->pcb_sp = (register_t)sf;
> }
>
> -/*
> - * cpu_exit is called as the last action during exit.
> - *
> - * We clean up a little and then call sched_exit() with the old proc as an
> - * argument.
> - */
> void
> cpu_exit(struct proc *p)
> {
> - pmap_deactivate(p);
> - sched_exit(p);
> }
>
> struct kmem_va_mode kv_physwait = {
> Index: arch/riscv64/riscv64/vm_machdep.c
> ===================================================================
> RCS file: /cvs/src/sys/arch/riscv64/riscv64/vm_machdep.c,v
> diff -u -p -r1.11 vm_machdep.c
> --- arch/riscv64/riscv64/vm_machdep.c 11 Apr 2023 00:45:08 -0000 1.11
> +++ arch/riscv64/riscv64/vm_machdep.c 16 May 2025 14:13:41 -0000
> @@ -104,17 +104,9 @@ cpu_fork(struct proc *p1, struct proc *p
> pcb->pcb_sp = (uint64_t)sf;
> }
>
> -/*
> - * cpu_exit is called as the last action during exit.
> - *
> - * We clean up a little and then call sched_exit() with the old proc as an
> - * argument.
> - */
> void
> cpu_exit(struct proc *p)
> {
> - pmap_deactivate(p);
> - sched_exit(p);
> }
>
> struct kmem_va_mode kv_physwait = {
> Index: arch/sh/sh/locore_c.c
> ===================================================================
> RCS file: /cvs/src/sys/arch/sh/sh/locore_c.c,v
> diff -u -p -r1.14 locore_c.c
> --- arch/sh/sh/locore_c.c 6 Jan 2023 19:10:18 -0000 1.14
> +++ arch/sh/sh/locore_c.c 16 May 2025 14:13:41 -0000
> @@ -156,9 +156,6 @@ cpu_exit(struct proc *p)
> {
> if (p->p_md.md_flags & MDP_STEP)
> _reg_write_2(SH_(BBRB), 0);
> -
> - pmap_deactivate(p);
> - sched_exit(p);
> }
>
> #ifndef P1_STACK
> Index: arch/sparc64/sparc64/vm_machdep.c
> ===================================================================
> RCS file: /cvs/src/sys/arch/sparc64/sparc64/vm_machdep.c,v
> diff -u -p -r1.45 vm_machdep.c
> --- arch/sparc64/sparc64/vm_machdep.c 29 Mar 2024 21:27:53 -0000 1.45
> +++ arch/sparc64/sparc64/vm_machdep.c 16 May 2025 14:13:41 -0000
> @@ -269,13 +269,6 @@ fpusave_proc(struct proc *p, int save)
> #endif
> }
>
> -/*
> - * cpu_exit is called as the last action during exit.
> - *
> - * We clean up a little and then call sched_exit() with the old proc
> - * as an argument. sched_exit() schedules the old vmspace and stack
> - * to be freed, then selects a new process to run.
> - */
> void
> cpu_exit(struct proc *p)
> {
> @@ -284,9 +277,6 @@ cpu_exit(struct proc *p)
> free(p->p_md.md_fpstate, M_SUBPROC, sizeof(struct fpstate));
> p->p_md.md_fpstate = NULL;
> }
> -
> - pmap_deactivate(p);
> - sched_exit(p);
> }
>
>
>
>
>
cpu_exit() diet