The branch main has been updated by jhb: URL: https://cgit.FreeBSD.org/src/commit/?id=187b46e1c4d761efe2e92f662d68c0f49cd04b44
commit 187b46e1c4d761efe2e92f662d68c0f49cd04b44 Author: John Baldwin <[email protected]> AuthorDate: 2026-03-26 17:39:52 +0000 Commit: John Baldwin <[email protected]> CommitDate: 2026-05-27 13:43:43 +0000 cpu_fork: Remove redundant assignments to td_pcb and td_frame cpu_thread_alloc() already sets these fields anytime td_kstack changes. Reviewed by: kib, andrew (arm changes) Sponsored by: AFRL, DARPA Pull Request: https://ron-dev.freebsd.org/FreeBSD/src/pulls/23 --- sys/amd64/amd64/vm_machdep.c | 6 +----- sys/arm/arm/vm_machdep.c | 8 ++------ sys/arm64/arm64/vm_machdep.c | 9 ++------- sys/i386/i386/vm_machdep.c | 12 +++++------- sys/powerpc/powerpc/vm_machdep.c | 8 ++------ sys/riscv/riscv/vm_machdep.c | 2 -- 6 files changed, 12 insertions(+), 33 deletions(-) diff --git a/sys/amd64/amd64/vm_machdep.c b/sys/amd64/amd64/vm_machdep.c index 2e180003e93d..e37f122dffa3 100644 --- a/sys/amd64/amd64/vm_machdep.c +++ b/sys/amd64/amd64/vm_machdep.c @@ -167,8 +167,6 @@ copy_thread(struct thread *td1, struct thread *td2) clear_pcb_flags(pcb2, PCB_TLSBASE); } - td2->td_frame = (struct trapframe *)td2->td_md.md_stack_base - 1; - /* * Set registers for trampoline to user mode. Leave space for the * return address on stack. These are the kernel mode register values. @@ -240,9 +238,7 @@ cpu_fork(struct thread *td1, struct proc *p2, struct thread *td2, int flags) return; } - /* Point the stack and pcb to the actual location */ - set_top_of_stack_td(td2); - td2->td_pcb = pcb2 = get_pcb_td(td2); + pcb2 = td2->td_pcb; copy_thread(td1, td2); diff --git a/sys/arm/arm/vm_machdep.c b/sys/arm/arm/vm_machdep.c index bee1c705fbbd..b1197255c281 100644 --- a/sys/arm/arm/vm_machdep.c +++ b/sys/arm/arm/vm_machdep.c @@ -97,9 +97,6 @@ cpu_fork(struct thread *td1, struct proc *p2, struct thread *td2, int flags) if ((flags & RFPROC) == 0) return; - /* Point the pcb to the top of the stack */ - pcb2 = (struct pcb *) - (td2->td_kstack + td2->td_kstack_pages * PAGE_SIZE) - 1; #ifdef VFP /* Store actual state of VFP */ if (curthread == td1) { @@ -107,7 +104,7 @@ cpu_fork(struct thread *td1, struct proc *p2, struct thread *td2, int flags) vfp_save_state(td1, td1->td_pcb); } #endif - td2->td_pcb = pcb2; + pcb2 = td2->td_pcb; /* Clone td1's pcb */ bcopy(td1->td_pcb, pcb2, sizeof(*pcb2)); @@ -116,8 +113,7 @@ cpu_fork(struct thread *td1, struct proc *p2, struct thread *td2, int flags) mdp2 = &p2->p_md; bcopy(&td1->td_proc->p_md, mdp2, sizeof(*mdp2)); - /* Point the frame to the stack in front of pcb and copy td1's frame */ - td2->td_frame = (struct trapframe *)pcb2 - 1; + /* Copy td1's frame */ *td2->td_frame = *td1->td_frame; /* diff --git a/sys/arm64/arm64/vm_machdep.c b/sys/arm64/arm64/vm_machdep.c index 4cb87ca9856e..01542848ab56 100644 --- a/sys/arm64/arm64/vm_machdep.c +++ b/sys/arm64/arm64/vm_machdep.c @@ -89,10 +89,7 @@ cpu_fork(struct thread *td1, struct proc *p2, struct thread *td2, int flags) #endif } - pcb2 = (struct pcb *)(td2->td_kstack + - td2->td_kstack_pages * PAGE_SIZE) - 1; - - td2->td_pcb = pcb2; + pcb2 = td2->td_pcb; bcopy(td1->td_pcb, pcb2, sizeof(*pcb2)); /* Clear the debug register state. */ @@ -100,14 +97,12 @@ cpu_fork(struct thread *td1, struct proc *p2, struct thread *td2, int flags) ptrauth_fork(td2, td1); - tf = STACKALIGN((struct trapframe *)pcb2 - 1); + tf = td2->td_frame; bcopy(td1->td_frame, tf, sizeof(*tf)); tf->tf_x[0] = 0; tf->tf_x[1] = 0; tf->tf_spsr = td1->td_frame->tf_spsr & (PSR_M_32 | PSR_DAIF); - td2->td_frame = tf; - /* Set the return value registers for fork() */ td2->td_pcb->pcb_x[PCB_X19] = (uintptr_t)fork_return; td2->td_pcb->pcb_x[PCB_X20] = (uintptr_t)td2; diff --git a/sys/i386/i386/vm_machdep.c b/sys/i386/i386/vm_machdep.c index 672ec9360c35..003f00070bff 100644 --- a/sys/i386/i386/vm_machdep.c +++ b/sys/i386/i386/vm_machdep.c @@ -232,9 +232,7 @@ cpu_fork(struct thread *td1, struct proc *p2, struct thread *td2, int flags) return; } - /* Point the pcb to the top of the stack */ - pcb2 = get_pcb_td(td2); - td2->td_pcb = pcb2; + pcb2 = td2->td_pcb; copy_thread(td1, td2); @@ -248,11 +246,7 @@ cpu_fork(struct thread *td1, struct proc *p2, struct thread *td2, int flags) /* * Copy the trap frame for the return to user mode as if from a * syscall. This copies most of the user mode register values. - * The -VM86_STACK_SPACE (-16) is so we can expand the trapframe - * if we go to vm86. */ - td2->td_frame = (struct trapframe *)((caddr_t)td2->td_pcb - - VM86_STACK_SPACE) - 1; bcopy(td1->td_frame, td2->td_frame, sizeof(struct trapframe)); /* Set child return values. */ @@ -381,6 +375,10 @@ cpu_thread_alloc(struct thread *td) struct pcb *pcb; struct xstate_hdr *xhdr; + /* + * The -VM86_STACK_SPACE (-16) is so we can expand the trapframe + * if we go to vm86. + */ td->td_pcb = pcb = get_pcb_td(td); td->td_frame = (struct trapframe *)((caddr_t)pcb - VM86_STACK_SPACE) - 1; diff --git a/sys/powerpc/powerpc/vm_machdep.c b/sys/powerpc/powerpc/vm_machdep.c index 00fdc301a7e7..1dc28739ad7c 100644 --- a/sys/powerpc/powerpc/vm_machdep.c +++ b/sys/powerpc/powerpc/vm_machdep.c @@ -123,9 +123,7 @@ cpu_fork(struct thread *td1, struct proc *p2, struct thread *td2, int flags) if (td1 == curthread) cpu_update_pcb(td1); - pcb = (struct pcb *)__align_down(td2->td_kstack + - td2->td_kstack_pages * PAGE_SIZE - sizeof(struct pcb), 0x40); - td2->td_pcb = pcb; + pcb = td2->td_pcb; /* Copy the pcb */ bcopy(td1->td_pcb, pcb, sizeof(struct pcb)); @@ -135,7 +133,7 @@ cpu_fork(struct thread *td1, struct proc *p2, struct thread *td2, int flags) * Copy the trap frame for the return to user mode as if from a * syscall. This copies most of the user mode register values. */ - tf = (struct trapframe *)pcb - 1; + tf = td2->td_frame; bcopy(td1->td_frame, tf, sizeof(*tf)); /* Set up trap frame. */ @@ -143,8 +141,6 @@ cpu_fork(struct thread *td1, struct proc *p2, struct thread *td2, int flags) tf->fixreg[FIRSTARG + 1] = 0; tf->cr &= ~0x10000000; - td2->td_frame = tf; - cf = (struct callframe *)tf - 1; memset(cf, 0, sizeof(struct callframe)); #if defined(__powerpc64__) && (!defined(_CALL_ELF) || _CALL_ELF == 1) diff --git a/sys/riscv/riscv/vm_machdep.c b/sys/riscv/riscv/vm_machdep.c index 206110157233..e718d522e572 100644 --- a/sys/riscv/riscv/vm_machdep.c +++ b/sys/riscv/riscv/vm_machdep.c @@ -100,8 +100,6 @@ cpu_fork(struct thread *td1, struct proc *p2, struct thread *td2, int flags) critical_exit(); } - cpu_set_pcb_frame(td2); - pcb2 = td2->td_pcb; bcopy(td1->td_pcb, pcb2, sizeof(*pcb2));
