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amd64: avoid acquiring dt lock if possible (which is the common case)

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Discussed with:	kib
MFC after:	1 week
This commit is contained in:
Mateusz Guzik 2017-10-20 03:30:02 +00:00
parent 95ce4c00ec
commit d95498d44f
6 changed files with 4 additions and 19 deletions
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5
sys/amd64/amd64/machdep.c
View File

@ -581,12 +581,9 @@ exec_setregs(struct thread *td, struct image_params *imgp, u_long stack)
struct trapframe *regs = td->td_frame;
struct pcb *pcb = td->td_pcb;
mtx_lock(&dt_lock);
if (td->td_proc->p_md.md_ldt != NULL)
user_ldt_free(td);
else
mtx_unlock(&dt_lock);
update_pcb_bases(pcb);
pcb->pcb_fsbase = 0;
pcb->pcb_gsbase = 0;

2
sys/amd64/amd64/sys_machdep.c
View File

@ -500,7 +500,7 @@ user_ldt_free(struct thread *td)
struct mdproc *mdp = &p->p_md;
struct proc_ldt *pldt;
mtx_assert(&dt_lock, MA_OWNED);
mtx_lock(&dt_lock);
if ((pldt = mdp->md_ldt) == NULL) {
mtx_unlock(&dt_lock);
return;

5
sys/amd64/amd64/vm_machdep.c
View File

@ -299,11 +299,8 @@ cpu_exit(struct thread *td)
/*
* If this process has a custom LDT, release it.
*/
mtx_lock(&dt_lock);
if (td->td_proc->p_md.md_ldt != 0)
if (td->td_proc->p_md.md_ldt != NULL)
user_ldt_free(td);
else
mtx_unlock(&dt_lock);
}
void

5
sys/amd64/ia32/ia32_signal.c
View File

@ -937,12 +937,9 @@ ia32_setregs(struct thread *td, struct image_params *imgp, u_long stack)
{
struct trapframe *regs = td->td_frame;
struct pcb *pcb = td->td_pcb;
mtx_lock(&dt_lock);
if (td->td_proc->p_md.md_ldt != NULL)
user_ldt_free(td);
else
mtx_unlock(&dt_lock);
#ifdef COMPAT_43
setup_lcall_gate();
#endif

3
sys/amd64/linux/linux_sysvec.c
View File

@ -453,11 +453,8 @@ linux_exec_setregs(struct thread *td, struct image_params *imgp, u_long stack)
struct trapframe *regs = td->td_frame;
struct pcb *pcb = td->td_pcb;
mtx_lock(&dt_lock);
if (td->td_proc->p_md.md_ldt != NULL)
user_ldt_free(td);
else
mtx_unlock(&dt_lock);
pcb->pcb_fsbase = 0;
pcb->pcb_gsbase = 0;

3
sys/amd64/linux32/linux32_sysvec.c
View File

@ -804,11 +804,8 @@ exec_linux_setregs(struct thread *td, struct image_params *imgp, u_long stack)
struct trapframe *regs = td->td_frame;
struct pcb *pcb = td->td_pcb;
mtx_lock(&dt_lock);
if (td->td_proc->p_md.md_ldt != NULL)
user_ldt_free(td);
else
mtx_unlock(&dt_lock);
critical_enter();
wrmsr(MSR_FSBASE, 0);