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arm: Unbreak debugging programs that use FP instructions

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Contrary to arm64, on armv7 get_vfpcontext/set_vfpcontext can be called
from cpu_ptrace. This can be triggered when gdb hits a breakpoint
in a userspace program.
Relax td == currthread assertion to account for that situation.
While here update an outdated comment in vfp_discard.

Reported by: Mark Millard <marklmi@yahoo.com>
Tested by: Mark Millard <marklmi@yahoo.com>
Differential Revision: https://reviews.freebsd.org/D38696
This commit is contained in:
Kornel Dulęba 2023-02-20 14:44:36 +00:00
parent f4a9e9fc79
commit 4d2427f2c4
2 changed files with 6 additions and 13 deletions
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17
sys/arm/arm/exec_machdep.c
View File

@ -100,19 +100,18 @@ get_vfpcontext(struct thread *td, mcontext_vfp_t *vfp)
{
struct pcb *pcb;
MPASS(td == curthread);
MPASS(td == curthread || TD_IS_SUSPENDED(td) ||
P_SHOULDSTOP(td->td_proc));
pcb = td->td_pcb;
if ((pcb->pcb_fpflags & PCB_FP_STARTED) != 0) {
if ((pcb->pcb_fpflags & PCB_FP_STARTED) != 0 && td == curthread) {
critical_enter();
vfp_store(&pcb->pcb_vfpstate, false);
critical_exit();
}
KASSERT(pcb->pcb_vfpsaved == &pcb->pcb_vfpstate,
("Called get_vfpcontext while the kernel is using the VFP"));
memcpy(vfp->mcv_reg, pcb->pcb_vfpstate.reg,
sizeof(vfp->mcv_reg));
vfp->mcv_fpscr = pcb->pcb_vfpstate.fpscr;
memcpy(vfp, &pcb->pcb_vfpstate, sizeof(*vfp));
}
/*
@ -123,19 +122,15 @@ set_vfpcontext(struct thread *td, mcontext_vfp_t *vfp)
{
struct pcb *pcb;
MPASS(td == curthread);
pcb = td->td_pcb;
if ((pcb->pcb_fpflags & PCB_FP_STARTED) != 0) {
if (td == curthread) {
critical_enter();
vfp_discard(td);
critical_exit();
}
KASSERT(pcb->pcb_vfpsaved == &pcb->pcb_vfpstate,
("Called set_vfpcontext while the kernel is using the VFP"));
memcpy(pcb->pcb_vfpstate.reg, vfp->mcv_reg,
sizeof(pcb->pcb_vfpstate.reg));
pcb->pcb_vfpstate.fpscr = vfp->mcv_fpscr;
memcpy(&pcb->pcb_vfpstate, vfp, sizeof(*vfp));
}
#endif

2
sys/arm/arm/vfp.c
View File

@ -334,8 +334,6 @@ vfp_store(struct vfp_state *vfpsave, boolean_t disable_vfp)
* The current thread is dying. If the state currently in the hardware belongs
* to the current thread, set fpcurthread to NULL to indicate that the VFP
* hardware state does not belong to any thread. If the VFP is on, turn it off.
* Called only from cpu_throw(), so we don't have to worry about a context
* switch here.
*/
void
vfp_discard(struct thread *td)