arm64: Support some per-thread sctlr_el1 fields

This will be used to enable MTE from userspace.

Sponsored by:	Arm Ltd
Differential Revision:	https://reviews.freebsd.org/D55950

5 files changed, 19 insertions, 1 deletions

diff --git a/sys/arm64/arm64/exec_machdep.c b/sys/arm64/arm64/exec_machdep.c
index 9f9b74e6a0e5..a2e1e42249b4 100644
--- a/sys/arm64/arm64/exec_machdep.c
+++ b/sys/arm64/arm64/exec_machdep.c
@@ -445,6 +445,7 @@ exec_setregs(struct thread *td, struct image_params *imgp, uintptr_t stack)
 	else
 		new_tcr = 0;
 	td->td_proc->p_md.md_tcr = new_tcr;
+	td->td_md.md_sctlr = 0;
 
 	/* TODO: should create a pmap function for this... */
 	tcr = READ_SPECIALREG(tcr_el1);
diff --git a/sys/arm64/arm64/pmap.c b/sys/arm64/arm64/pmap.c
index 4ba2fb6f6678..595fba2da411 100644
--- a/sys/arm64/arm64/pmap.c
+++ b/sys/arm64/arm64/pmap.c
@@ -9325,6 +9325,7 @@ pmap_switch(struct thread *new)
 {
 	pcpu_bp_harden bp_harden;
 	struct pcb *pcb;
+	uint64_t sctlr;
 
 	/* Store the new curthread */
 	PCPU_SET(curthread, new);
@@ -9333,6 +9334,16 @@ pmap_switch(struct thread *new)
 	pcb = new->td_pcb;
 	PCPU_SET(curpcb, pcb);
 
+	if ((new->td_proc->p_flag & P_KPROC) == 0) {
+		sctlr = READ_SPECIALREG(sctlr_el1);
+		if ((sctlr & SCTLR_USER_MASK) != new->td_md.md_sctlr) {
+			sctlr &= ~SCTLR_USER_MASK;
+			sctlr |= new->td_md.md_sctlr;
+			WRITE_SPECIALREG(sctlr_el1, sctlr);
+			isb();
+		}
+	}
+
 	/*
 	 * TODO: We may need to flush the cache here if switching
 	 * to a user process.
diff --git a/sys/arm64/arm64/vm_machdep.c b/sys/arm64/arm64/vm_machdep.c
index b46cb8793409..4cb87ca9856e 100644
--- a/sys/arm64/arm64/vm_machdep.c
+++ b/sys/arm64/arm64/vm_machdep.c
@@ -123,6 +123,8 @@ cpu_fork(struct thread *td1, struct proc *p2, struct thread *td2, int flags)
 	/* Copy the TCR_EL1 value */
 	td2->td_proc->p_md.md_tcr = td1->td_proc->p_md.md_tcr;
 
+	td2->td_md.md_sctlr = td1->td_md.md_sctlr;
+
 #if defined(PERTHREAD_SSP)
 	/* Set the new canary */
 	arc4random_buf(&td2->td_md.md_canary, sizeof(td2->td_md.md_canary));
@@ -192,6 +194,8 @@ cpu_copy_thread(struct thread *td, struct thread *td0)
 	td->td_md.md_spinlock_count = 1;
 	td->td_md.md_saved_daif = PSR_DAIF_DEFAULT;
 
+	td->td_md.md_sctlr = td0->td_md.md_sctlr;
+
 #if defined(PERTHREAD_SSP)
 	/* Set the new canary */
 	arc4random_buf(&td->td_md.md_canary, sizeof(td->td_md.md_canary));
diff --git a/sys/arm64/include/armreg.h b/sys/arm64/include/armreg.h
index 6447f0064d33..4233a01d143c 100644
--- a/sys/arm64/include/armreg.h
+++ b/sys/arm64/include/armreg.h
@@ -2803,6 +2803,7 @@
      SCTLR_SA |				\
      SCTLR_C |				\
      SCTLR_M)
+#define	SCTLR_USER_MASK	(SCTLR_ATA0 | SCTLR_TCF0_MASK)
 
 /* SCTLR_EL12 */
 #define	SCTLR_EL12_REG			MRS_REG_ALT_NAME(SCTLR_EL12)
diff --git a/sys/arm64/include/proc.h b/sys/arm64/include/proc.h
index b40990e89385..d5879a794269 100644
--- a/sys/arm64/include/proc.h
+++ b/sys/arm64/include/proc.h
@@ -70,7 +70,8 @@ struct mdthread {
 	int md_efirt_dis_pf;
 
 	int md_reserved0;
-	uint64_t md_reserved[2];
+	uint64_t md_sctlr;
+	uint64_t md_reserved1;
 };
 
 struct mdproc {