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arm: Fix initialization of VFP context

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Make sure that pcb_vfpsaved is always initialized.
Create a vfp_new_thread helper that is heavily based on the arm64 logic.
While here remove un unnecessary assigment and add an assertion
to make sure that it's been properly initialized before we return
from a VFP exception.

Reported by: Mark Millard <marklmi@yahoo.com>
Tested by: Mark Millard <marklmi@yahoo.com>
Differential Revision: https://reviews.freebsd.org/D38698
This commit is contained in:
Kornel Dulęba 2023-02-20 14:48:40 +00:00
parent 4d2427f2c4
commit 98c666cf87
4 changed files with 40 additions and 5 deletions
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1
sys/arm/arm/machdep.c
View File

@ -380,6 +380,7 @@ init_proc0(vm_offset_t kstack)
thread0.td_pcb->pcb_fpflags = 0;
thread0.td_pcb->pcb_vfpcpu = -1;
thread0.td_pcb->pcb_vfpstate.fpscr = VFPSCR_DN;
thread0.td_pcb->pcb_vfpsaved = &thread0.td_pcb->pcb_vfpstate;
thread0.td_frame = &proc0_tf;
pcpup->pc_curpcb = thread0.td_pcb;
}

33
sys/arm/arm/vfp.c
View File

@ -34,6 +34,7 @@ __FBSDID("$FreeBSD$");
#ifdef VFP
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/limits.h>
#include <sys/proc.h>
#include <sys/imgact_elf.h>
#include <sys/kernel.h>
@ -251,17 +252,45 @@ vfp_bounce(u_int addr, u_int insn, struct trapframe *frame, int code)
curpcb = curthread->td_pcb;
cpu = PCPU_GET(cpuid);
if (curpcb->pcb_vfpcpu != cpu || curthread != PCPU_GET(fpcurthread)) {
if (curpcb->pcb_vfpsaved == NULL)
curpcb->pcb_vfpsaved = &curpcb->pcb_vfpstate;
vfp_restore(curpcb->pcb_vfpsaved);
curpcb->pcb_vfpcpu = cpu;
PCPU_SET(fpcurthread, curthread);
}
critical_exit();
KASSERT(curpcb->pcb_vfpsaved == &curpcb->pcb_vfpstate,
("Kernel VFP state in use when entering userspace"));
return (0);
}
/*
* Update the VFP state for a forked process or new thread. The PCB will
* have been copied from the old thread.
* The code is heavily based on arm64 logic.
*/
void
vfp_new_thread(struct thread *newtd, struct thread *oldtd, bool fork)
{
struct pcb *newpcb;
newpcb = newtd->td_pcb;
/* Kernel threads start with clean VFP */
if ((oldtd->td_pflags & TDP_KTHREAD) != 0) {
newpcb->pcb_fpflags &=
~(PCB_FP_STARTED | PCB_FP_KERN | PCB_FP_NOSAVE);
} else {
MPASS((newpcb->pcb_fpflags & (PCB_FP_KERN|PCB_FP_NOSAVE)) == 0);
if (!fork) {
newpcb->pcb_fpflags &= ~PCB_FP_STARTED;
}
}
newpcb->pcb_vfpsaved = &newpcb->pcb_vfpstate;
newpcb->pcb_vfpcpu = UINT_MAX;
}
/*
* Restore the given state to the VFP hardware.
*/

10
sys/arm/arm/vm_machdep.c
View File

@ -137,9 +137,9 @@ cpu_fork(struct thread *td1, struct proc *p2, struct thread *td2, int flags)
pcb2->pcb_regs.sf_sp = STACKALIGN(td2->td_frame);
pcb2->pcb_regs.sf_tpidrurw = (register_t)get_tls();
pcb2->pcb_vfpcpu = -1;
pcb2->pcb_vfpsaved = &pcb2->pcb_vfpstate;
pcb2->pcb_vfpstate.fpscr = initial_fpscr;
#ifdef VFP
vfp_new_thread(td2, td1, true);
#endif
tf = td2->td_frame;
tf->tf_spsr &= ~PSR_C;
@ -216,6 +216,10 @@ cpu_copy_thread(struct thread *td, struct thread *td0)
td->td_frame->tf_spsr &= ~PSR_C;
td->td_frame->tf_r0 = 0;
#ifdef VFP
vfp_new_thread(td, td0, false);
#endif
/* Setup to release spin count in fork_exit(). */
td->td_md.md_spinlock_count = 1;
td->td_md.md_saved_cspr = PSR_SVC32_MODE;

1
sys/arm/include/vfp.h
View File

@ -157,6 +157,7 @@ struct vfp_state {
void get_vfpcontext(struct thread *, mcontext_vfp_t *);
void set_vfpcontext(struct thread *, mcontext_vfp_t *);
void vfp_init(void);
void vfp_new_thread(struct thread*, struct thread*, bool);
void vfp_store(struct vfp_state *, boolean_t);
void vfp_discard(struct thread *);
void vfp_restore_state(void);