git: e45132e97803 - main - arm64: Add the SVE registers to the signal frame

The branch main has been updated by andrew:

URL: https://cgit.FreeBSD.org/src/commit/?id=e45132e978030f0aa964d975a9fbad5614f260bd

commit e45132e978030f0aa964d975a9fbad5614f260bd
Author:     Andrew Turner <andrew@FreeBSD.org>
AuthorDate: 2024-09-27 13:37:03 +0000
Commit:     Andrew Turner <andrew@FreeBSD.org>
CommitDate: 2024-09-30 12:04:23 +0000

    arm64: Add the SVE registers to the signal frame
    
    Use the new extended register support in the arm64 signal frame to
    handle the SVE registers.
    
    As these registers alias the VFP registers we use the floating point
    register values to restore the lower bits of the SVE registers. This
    is to support software that doesn't understand SVE to continue working.
    
    Sponsored by:   Arm Ltd
    Differential Revision:  https://reviews.freebsd.org/D43307
---
 sys/arm64/arm64/exec_machdep.c | 88 +++++++++++++++++++++++++++++++++++++++++-
 sys/arm64/include/ucontext.h   |  8 ++++
 2 files changed, 94 insertions(+), 2 deletions(-)

diff --git a/sys/arm64/arm64/exec_machdep.c b/sys/arm64/arm64/exec_machdep.c
index 6fece751cc25..6a536233a62d 100644
--- a/sys/arm64/arm64/exec_machdep.c
+++ b/sys/arm64/arm64/exec_machdep.c
@@ -463,9 +463,10 @@ set_mcontext(struct thread *td, mcontext_t *mcp)
 #define	PSR_13_MASK	0xfffffffful
 	struct arm64_reg_context ctx;
 	struct trapframe *tf = td->td_frame;
+	struct pcb *pcb;
 	uint64_t spsr;
 	vm_offset_t addr;
-	int error;
+	int error, seen_types;
 	bool done;
 
 	spsr = mcp->mc_gpregs.gp_spsr;
@@ -511,7 +512,11 @@ set_mcontext(struct thread *td, mcontext_t *mcp)
 	/* Read any register contexts we find */
 	if (mcp->mc_ptr != 0) {
 		addr = mcp->mc_ptr;
+		pcb = td->td_pcb;
+
+#define	CTX_TYPE_FLAG_SVE	(1 << 0)
 
+		seen_types = 0;
 		done = false;
 		do {
 			if (!__is_aligned(addr,
@@ -523,6 +528,38 @@ set_mcontext(struct thread *td, mcontext_t *mcp)
 				return (error);
 
 			switch (ctx.ctx_id) {
+#ifdef VFP
+			case ARM64_CTX_SVE: {
+				struct sve_context sve_ctx;
+				size_t buf_size;
+
+				if ((seen_types & CTX_TYPE_FLAG_SVE) != 0)
+					return (EINVAL);
+				seen_types |= CTX_TYPE_FLAG_SVE;
+
+				if (pcb->pcb_svesaved == NULL)
+					return (EINVAL);
+
+				/* XXX: Check pcb_svesaved is valid */
+
+				buf_size = sve_buf_size(td);
+				/* Check the size is valid */
+				if (ctx.ctx_size !=
+				    (sizeof(sve_ctx) + buf_size))
+					return (EINVAL);
+
+				memset(pcb->pcb_svesaved, 0,
+				    sve_max_buf_size());
+
+				/* Copy the SVE registers from userspace */
+				if (copyin((void *)(addr + sizeof(sve_ctx)),
+				    pcb->pcb_svesaved, buf_size) != 0)
+					return (EINVAL);
+
+				pcb->pcb_fpflags |= PCB_FP_SVEVALID;
+				break;
+			}
+#endif
 			case ARM64_CTX_END:
 				done = true;
 				break;
@@ -532,6 +569,8 @@ set_mcontext(struct thread *td, mcontext_t *mcp)
 
 			addr += ctx.ctx_size;
 		} while (!done);
+
+#undef CTX_TYPE_FLAG_SVE
 	}
 
 	return (0);
@@ -592,7 +631,7 @@ set_fpcontext(struct thread *td, mcontext_t *mcp)
 		    sizeof(mcp->mc_fpregs.fp_q));
 		curpcb->pcb_fpustate.vfp_fpcr = mcp->mc_fpregs.fp_cr;
 		curpcb->pcb_fpustate.vfp_fpsr = mcp->mc_fpregs.fp_sr;
-		curpcb->pcb_fpflags = mcp->mc_fpregs.fp_flags & PCB_FP_USERMASK;
+		curpcb->pcb_fpflags = mcp->mc_fpregs.fp_flags & PCB_FP_STARTED;
 	}
 #endif
 }
@@ -612,6 +651,13 @@ sys_sigreturn(struct thread *td, struct sigreturn_args *uap)
 	if (error != 0)
 		return (error);
 
+	/*
+	 * Sync the VFP and SVE registers. To be backwards compatible we
+	 * use the VFP registers to restore the lower bits of the SVE
+	 * register it aliases.
+	 */
+	vfp_to_sve_sync(td);
+
 	/* Restore signal mask. */
 	kern_sigprocmask(td, SIG_SETMASK, &uc.uc_sigmask, NULL, 0);
 
@@ -637,9 +683,47 @@ sendsig_ctx_end(struct thread *td, vm_offset_t *addrp)
 	return (true);
 }
 
+static bool
+sendsig_ctx_sve(struct thread *td, vm_offset_t *addrp)
+{
+	struct sve_context ctx;
+	struct pcb *pcb;
+	size_t buf_size;
+	vm_offset_t ctx_addr;
+
+	pcb = td->td_pcb;
+	/* Do nothing if sve hasn't started */
+	if (pcb->pcb_svesaved == NULL)
+		return (true);
+
+	MPASS(pcb->pcb_svesaved != NULL);
+
+	buf_size = sve_buf_size(td);
+
+	/* Address for the full context */
+	*addrp -= sizeof(ctx) + buf_size;
+	ctx_addr = *addrp;
+
+	memset(&ctx, 0, sizeof(ctx));
+	ctx.sve_ctx.ctx_id = ARM64_CTX_SVE;
+	ctx.sve_ctx.ctx_size = sizeof(ctx) + buf_size;
+	ctx.sve_vector_len = pcb->pcb_sve_len;
+	ctx.sve_flags = 0;
+
+	/* Copy out the header and data */
+	if (copyout(&ctx, (void *)ctx_addr, sizeof(ctx)) != 0)
+		return (false);
+	if (copyout(pcb->pcb_svesaved, (void *)(ctx_addr + sizeof(ctx)),
+	    buf_size) != 0)
+		return (false);
+
+	return (true);
+}
+
 typedef bool(*ctx_func)(struct thread *, vm_offset_t *);
 static const ctx_func ctx_funcs[] = {
 	sendsig_ctx_end,	/* Must be first to end the linked list */
+	sendsig_ctx_sve,
 	NULL,
 };
 
diff --git a/sys/arm64/include/ucontext.h b/sys/arm64/include/ucontext.h
index dedbd061ec6b..a4f0ee243b3a 100644
--- a/sys/arm64/include/ucontext.h
+++ b/sys/arm64/include/ucontext.h
@@ -62,6 +62,14 @@ struct arm64_reg_context {
 };
 
 #define	ARM64_CTX_END		0xa5a5a5a5
+#define	ARM64_CTX_SVE		0x00657673
+
+struct sve_context {
+	struct arm64_reg_context sve_ctx;
+	__uint16_t	sve_vector_len;
+	__uint16_t	sve_flags;
+	__uint16_t	sve_reserved[2];
+};
 
 struct __mcontext {
 	struct gpregs	mc_gpregs;