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x86: Reduce code duplication in cpu_fork() and cpu_copy_thread().

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Add copy_thread() to hold shared code.

Reviewed by:	kib
MFC after:	1 week
Sponsored by:	Netflix
Differential Revision:	https://reviews.freebsd.org/D29228
This commit is contained in:
John Baldwin 2021-03-18 12:13:17 -07:00
parent c39dda8192
commit a7883464fc
2 changed files with 137 additions and 214 deletions
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167
sys/amd64/amd64/vm_machdep.c
View File

@ -136,6 +136,65 @@ alloc_fpusave(int flags)
return (res);
}
/*
* Common code shared between cpu_fork() and cpu_copy_thread() for
* initializing a thread.
*/
static void
copy_thread(struct thread *td1, struct thread *td2)
{
struct pcb *pcb2;
pcb2 = td2->td_pcb;
/* Ensure that td1's pcb is up to date for user threads. */
if ((td2->td_pflags & TDP_KTHREAD) == 0) {
MPASS(td1 == curthread);
fpuexit(td1);
update_pcb_bases(td1->td_pcb);
}
/* Copy td1's pcb */
bcopy(td1->td_pcb, pcb2, sizeof(*pcb2));
/* Properly initialize pcb_save */
pcb2->pcb_save = get_pcb_user_save_pcb(pcb2);
/* Kernel threads start with clean FPU and segment bases. */
if ((td2->td_pflags & TDP_KTHREAD) != 0) {
pcb2->pcb_fsbase = 0;
pcb2->pcb_gsbase = 0;
clear_pcb_flags(pcb2, PCB_FPUINITDONE | PCB_USERFPUINITDONE |
PCB_KERNFPU | PCB_KERNFPU_THR);
} else {
MPASS((pcb2->pcb_flags & (PCB_KERNFPU | PCB_KERNFPU_THR)) == 0);
bcopy(get_pcb_user_save_td(td1), get_pcb_user_save_pcb(pcb2),
cpu_max_ext_state_size);
}
/*
* Set registers for trampoline to user mode. Leave space for the
* return address on stack. These are the kernel mode register values.
*/
pcb2->pcb_r12 = (register_t)fork_return; /* fork_trampoline argument */
pcb2->pcb_rbp = 0;
pcb2->pcb_rsp = (register_t)td2->td_frame - sizeof(void *);
pcb2->pcb_rbx = (register_t)td2; /* fork_trampoline argument */
pcb2->pcb_rip = (register_t)fork_trampoline;
/*-
* pcb2->pcb_dr*: cloned above.
* pcb2->pcb_savefpu: cloned above.
* pcb2->pcb_flags: cloned above.
* pcb2->pcb_onfault: cloned above (always NULL here?).
* pcb2->pcb_[fg]sbase: cloned above
*/
/* Setup to release spin count in fork_exit(). */
td2->td_md.md_spinlock_count = 1;
td2->td_md.md_saved_flags = PSL_KERNEL | PSL_I;
pmap_thread_init_invl_gen(td2);
}
/*
* Finish a fork operation, with process p2 nearly set up.
* Copy and update the pcb, set up the stack so that the child
@ -164,36 +223,13 @@ cpu_fork(struct thread *td1, struct proc *p2, struct thread *td2, int flags)
return;
}
/* Ensure that td1's pcb is up to date for user processes. */
if ((td2->td_pflags & TDP_KTHREAD) == 0) {
MPASS(td1 == curthread);
fpuexit(td1);
update_pcb_bases(td1->td_pcb);
}
/* Point the stack and pcb to the actual location */
set_top_of_stack_td(td2);
td2->td_pcb = pcb2 = get_pcb_td(td2);
/* Copy td1's pcb */
bcopy(td1->td_pcb, pcb2, sizeof(*pcb2));
copy_thread(td1, td2);
/* Properly initialize pcb_save */
pcb2->pcb_save = get_pcb_user_save_pcb(pcb2);
/* Kernel processes start with clean FPU and segment bases. */
if ((td2->td_pflags & TDP_KTHREAD) != 0) {
pcb2->pcb_fsbase = 0;
pcb2->pcb_gsbase = 0;
clear_pcb_flags(pcb2, PCB_FPUINITDONE | PCB_USERFPUINITDONE |
PCB_KERNFPU | PCB_KERNFPU_THR);
} else {
MPASS((pcb2->pcb_flags & (PCB_KERNFPU | PCB_KERNFPU_THR)) == 0);
bcopy(get_pcb_user_save_td(td1), get_pcb_user_save_pcb(pcb2),
cpu_max_ext_state_size);
}
/* Point mdproc and then copy over td1's contents */
/* Point mdproc and then copy over p1's contents */
mdp2 = &p2->p_md;
bcopy(&p1->p_md, mdp2, sizeof(*mdp2));
@ -215,29 +251,7 @@ cpu_fork(struct thread *td1, struct proc *p2, struct thread *td2, int flags)
*/
td2->td_frame->tf_rflags &= ~PSL_T;
/*
* Set registers for trampoline to user mode. Leave space for the
* return address on stack. These are the kernel mode register values.
*/
pcb2->pcb_r12 = (register_t)fork_return; /* fork_trampoline argument */
pcb2->pcb_rbp = 0;
pcb2->pcb_rsp = (register_t)td2->td_frame - sizeof(void *);
pcb2->pcb_rbx = (register_t)td2; /* fork_trampoline argument */
pcb2->pcb_rip = (register_t)fork_trampoline;
/*-
* pcb2->pcb_dr*: cloned above.
* pcb2->pcb_savefpu: cloned above.
* pcb2->pcb_flags: cloned above.
* pcb2->pcb_onfault: cloned above (always NULL here?).
* pcb2->pcb_[fg]sbase: cloned above
*/
/* Setup to release spin count in fork_exit(). */
td2->td_md.md_spinlock_count = 1;
td2->td_md.md_saved_flags = PSL_KERNEL | PSL_I;
pmap_thread_init_invl_gen(td2);
/* As an i386, do not copy io permission bitmap. */
/* As on i386, do not copy io permission bitmap. */
pcb2->pcb_tssp = NULL;
/* New segment registers. */
@ -275,7 +289,7 @@ cpu_fork(struct thread *td1, struct proc *p2, struct thread *td2, int flags)
* pcb_rsp is loaded pointing to the cpu_switch() stack frame
* containing the return address when exiting cpu_switch.
* This will normally be to fork_trampoline(), which will have
* %ebx loaded with the new proc's pointer. fork_trampoline()
* %rbx loaded with the new proc's pointer. fork_trampoline()
* will set up a stack to call fork_return(p, frame); to complete
* the return to user-mode.
*/
@ -571,38 +585,7 @@ cpu_set_syscall_retval(struct thread *td, int error)
void
cpu_copy_thread(struct thread *td, struct thread *td0)
{
struct pcb *pcb2;
pcb2 = td->td_pcb;
/* Ensure that td0's pcb is up to date for user threads. */
if ((td->td_pflags & TDP_KTHREAD) == 0) {
MPASS(td0 == curthread);
fpuexit(td0);
update_pcb_bases(td0->td_pcb);
}
/*
* Copy the upcall pcb. This loads kernel regs.
* Those not loaded individually below get their default
* values here.
*/
bcopy(td0->td_pcb, pcb2, sizeof(*pcb2));
pcb2->pcb_save = get_pcb_user_save_pcb(pcb2);
/* Kernel threads start with clean FPU and segment bases. */
if ((td->td_pflags & TDP_KTHREAD) != 0) {
pcb2->pcb_fsbase = 0;
pcb2->pcb_gsbase = 0;
clear_pcb_flags(pcb2, PCB_FPUINITDONE | PCB_USERFPUINITDONE |
PCB_KERNFPU | PCB_KERNFPU_THR);
} else {
MPASS((pcb2->pcb_flags & (PCB_KERNFPU | PCB_KERNFPU_THR)) == 0);
bcopy(get_pcb_user_save_td(td0), pcb2->pcb_save,
cpu_max_ext_state_size);
}
set_pcb_flags_raw(pcb2, PCB_FULL_IRET);
copy_thread(td0, td);
/*
* Copy user general-purpose registers.
@ -620,27 +603,7 @@ cpu_copy_thread(struct thread *td, struct thread *td0)
*/
td->td_frame->tf_rflags &= ~PSL_T;
/*
* Set registers for trampoline to user mode. Leave space for the
* return address on stack. These are the kernel mode register values.
*/
pcb2->pcb_r12 = (register_t)fork_return; /* trampoline arg */
pcb2->pcb_rbp = 0;
pcb2->pcb_rsp = (register_t)td->td_frame - sizeof(void *); /* trampoline arg */
pcb2->pcb_rbx = (register_t)td; /* trampoline arg */
pcb2->pcb_rip = (register_t)fork_trampoline;
/*
* If we didn't copy the pcb, we'd need to do the following registers:
* pcb2->pcb_dr*: cloned above.
* pcb2->pcb_savefpu: cloned above.
* pcb2->pcb_onfault: cloned above (always NULL here?).
* pcb2->pcb_[fg]sbase: cloned above
*/
/* Setup to release spin count in fork_exit(). */
td->td_md.md_spinlock_count = 1;
td->td_md.md_saved_flags = PSL_KERNEL | PSL_I;
pmap_thread_init_invl_gen(td);
set_pcb_flags_raw(td->td_pcb, PCB_FULL_IRET);
}
/*

184
sys/i386/i386/vm_machdep.c
View File

@ -133,6 +133,74 @@ alloc_fpusave(int flags)
}
return (res);
}
/*
* Common code shared between cpu_fork() and cpu_copy_thread() for
* initializing a thread.
*/
static void
copy_thread(struct thread *td1, struct thread *td2)
{
struct pcb *pcb2;
pcb2 = td2->td_pcb;
/* Ensure that td1's pcb is up to date for user threads. */
if ((td2->td_pflags & TDP_KTHREAD) == 0) {
MPASS(td1 == curthread);
td1->td_pcb->pcb_gs = rgs();
critical_enter();
if (PCPU_GET(fpcurthread) == td1)
npxsave(td1->td_pcb->pcb_save);
critical_exit();
}
/* Copy td1's pcb */
bcopy(td1->td_pcb, pcb2, sizeof(*pcb2));
/* Properly initialize pcb_save */
pcb2->pcb_save = get_pcb_user_save_pcb(pcb2);
/* Kernel threads start with clean NPX and segment bases. */
if ((td2->td_pflags & TDP_KTHREAD) != 0) {
pcb2->pcb_gs = _udatasel;
set_fsbase(td2, 0);
set_gsbase(td2, 0);
pcb2->pcb_flags &= ~(PCB_NPXINITDONE | PCB_NPXUSERINITDONE |
PCB_KERNNPX | PCB_KERNNPX_THR);
} else {
MPASS((pcb2->pcb_flags & (PCB_KERNNPX | PCB_KERNNPX_THR)) == 0);
bcopy(get_pcb_user_save_td(td1), get_pcb_user_save_pcb(pcb2),
cpu_max_ext_state_size);
}
/*
* Set registers for trampoline to user mode. Leave space for the
* return address on stack. These are the kernel mode register values.
*/
pcb2->pcb_edi = 0;
pcb2->pcb_esi = (int)fork_return; /* trampoline arg */
pcb2->pcb_ebp = 0;
pcb2->pcb_esp = (int)td2->td_frame - sizeof(void *); /* trampoline arg */
pcb2->pcb_ebx = (int)td2; /* trampoline arg */
pcb2->pcb_eip = (int)fork_trampoline + setidt_disp;
/*
* If we didn't copy the pcb, we'd need to do the following registers:
* pcb2->pcb_cr3: cloned above.
* pcb2->pcb_dr*: cloned above.
* pcb2->pcb_savefpu: cloned above.
* pcb2->pcb_flags: cloned above.
* pcb2->pcb_onfault: cloned above (always NULL here?).
* pcb2->pcb_gs: cloned above.
* pcb2->pcb_ext: cleared below.
*/
pcb2->pcb_ext = NULL;
/* Setup to release spin count in fork_exit(). */
td2->td_md.md_spinlock_count = 1;
td2->td_md.md_saved_flags = PSL_KERNEL | PSL_I;
}
/*
* Finish a fork operation, with process p2 nearly set up.
* Copy and update the pcb, set up the stack so that the child
@ -167,38 +235,11 @@ cpu_fork(struct thread *td1, struct proc *p2, struct thread *td2, int flags)
return;
}
/* Ensure that td1's pcb is up to date for user processes. */
if ((td2->td_pflags & TDP_KTHREAD) == 0) {
MPASS(td1 == curthread);
td1->td_pcb->pcb_gs = rgs();
critical_enter();
if (PCPU_GET(fpcurthread) == td1)
npxsave(td1->td_pcb->pcb_save);
critical_exit();
}
/* Point the pcb to the top of the stack */
pcb2 = get_pcb_td(td2);
td2->td_pcb = pcb2;
/* Copy td1's pcb */
bcopy(td1->td_pcb, pcb2, sizeof(*pcb2));
/* Properly initialize pcb_save */
pcb2->pcb_save = get_pcb_user_save_pcb(pcb2);
/* Kernel processes start with clean NPX and segment bases. */
if ((td2->td_pflags & TDP_KTHREAD) != 0) {
pcb2->pcb_gs = _udatasel;
set_fsbase(td2, 0);
set_gsbase(td2, 0);
pcb2->pcb_flags &= ~(PCB_NPXINITDONE | PCB_NPXUSERINITDONE |
PCB_KERNNPX | PCB_KERNNPX_THR);
} else {
MPASS((pcb2->pcb_flags & (PCB_KERNNPX | PCB_KERNNPX_THR)) == 0);
bcopy(get_pcb_user_save_td(td1), get_pcb_user_save_pcb(pcb2),
cpu_max_ext_state_size);
}
copy_thread(td1, td2);
/* Point mdproc and then copy over td1's contents */
mdp2 = &p2->p_md;
@ -225,30 +266,13 @@ cpu_fork(struct thread *td1, struct proc *p2, struct thread *td2, int flags)
*/
td2->td_frame->tf_eflags &= ~PSL_T;
/*
* Set registers for trampoline to user mode. Leave space for the
* return address on stack. These are the kernel mode register values.
*/
/* Set cr3 for the new process. */
pcb2->pcb_cr3 = pmap_get_cr3(vmspace_pmap(p2->p_vmspace));
pcb2->pcb_edi = 0;
pcb2->pcb_esi = (int)fork_return; /* fork_trampoline argument */
pcb2->pcb_ebp = 0;
pcb2->pcb_esp = (int)td2->td_frame - sizeof(void *);
pcb2->pcb_ebx = (int)td2; /* fork_trampoline argument */
pcb2->pcb_eip = (int)fork_trampoline + setidt_disp;
/*-
* pcb2->pcb_dr*: cloned above.
* pcb2->pcb_savefpu: cloned above.
* pcb2->pcb_flags: cloned above.
* pcb2->pcb_onfault: cloned above (always NULL here?).
* pcb2->pcb_gs: cloned above.
* pcb2->pcb_ext: cleared below.
*/
/*
* XXX don't copy the i/o pages. this should probably be fixed.
*/
pcb2->pcb_ext = 0;
pcb2->pcb_ext = NULL;
/* Copy the LDT, if necessary. */
mtx_lock_spin(&dt_lock);
@ -264,10 +288,6 @@ cpu_fork(struct thread *td1, struct proc *p2, struct thread *td2, int flags)
}
mtx_unlock_spin(&dt_lock);
/* Setup to release spin count in fork_exit(). */
td2->td_md.md_spinlock_count = 1;
td2->td_md.md_saved_flags = PSL_KERNEL | PSL_I;
/*
* Now, cpu_switch() can schedule the new process.
* pcb_esp is loaded pointing to the cpu_switch() stack frame
@ -435,41 +455,7 @@ cpu_set_syscall_retval(struct thread *td, int error)
void
cpu_copy_thread(struct thread *td, struct thread *td0)
{
struct pcb *pcb2;
/* Point the pcb to the top of the stack. */
pcb2 = td->td_pcb;
/* Ensure that td0's pcb is up to date for user threads. */
if ((td->td_pflags & TDP_KTHREAD) == 0) {
MPASS(td0 == curthread);
td0->td_pcb->pcb_gs = rgs();
critical_enter();
if (PCPU_GET(fpcurthread) == td0)
npxsave(td0->td_pcb->pcb_save);
critical_exit();
}
/*
* Copy the upcall pcb. This loads kernel regs.
* Those not loaded individually below get their default
* values here.
*/
bcopy(td0->td_pcb, pcb2, sizeof(*pcb2));
pcb2->pcb_save = get_pcb_user_save_pcb(pcb2);
/* Kernel threads start with clean NPX and segment bases. */
if ((td->td_pflags & TDP_KTHREAD) != 0) {
pcb2->pcb_gs = _udatasel;
set_fsbase(td, 0);
set_gsbase(td, 0);
pcb2->pcb_flags &= ~(PCB_NPXINITDONE | PCB_NPXUSERINITDONE |
PCB_KERNNPX | PCB_KERNNPX_THR);
} else {
MPASS((pcb2->pcb_flags & (PCB_KERNNPX | PCB_KERNNPX_THR)) == 0);
bcopy(get_pcb_user_save_td(td0), pcb2->pcb_save,
cpu_max_ext_state_size);
}
copy_thread(td0, td);
/*
* Copy user general-purpose registers.
@ -486,32 +472,6 @@ cpu_copy_thread(struct thread *td, struct thread *td0)
* instruction after returning to userland.
*/
td->td_frame->tf_eflags &= ~PSL_T;
/*
* Set registers for trampoline to user mode. Leave space for the
* return address on stack. These are the kernel mode register values.
*/
pcb2->pcb_edi = 0;
pcb2->pcb_esi = (int)fork_return; /* trampoline arg */
pcb2->pcb_ebp = 0;
pcb2->pcb_esp = (int)td->td_frame - sizeof(void *); /* trampoline arg */
pcb2->pcb_ebx = (int)td; /* trampoline arg */
pcb2->pcb_eip = (int)fork_trampoline + setidt_disp;
/*
* If we didn't copy the pcb, we'd need to do the following registers:
* pcb2->pcb_cr3: cloned above.
* pcb2->pcb_dr*: cloned above.
* pcb2->pcb_savefpu: cloned above.
* pcb2->pcb_flags: cloned above.
* pcb2->pcb_onfault: cloned above (always NULL here?).
* pcb2->pcb_gs: cloned above.
* pcb2->pcb_ext: cleared below.
*/
pcb2->pcb_ext = NULL;
/* Setup to release spin count in fork_exit(). */
td->td_md.md_spinlock_count = 1;
td->td_md.md_saved_flags = PSL_KERNEL | PSL_I;
}
/*