git: 67d61d18bb8d - main - amd64: extract uiomove_mem() from memrw()

The branch main has been updated by kib:

URL: https://cgit.FreeBSD.org/src/commit/?id=67d61d18bb8debb4ffc51ef2248aa37ed0bfb8f5

commit 67d61d18bb8debb4ffc51ef2248aa37ed0bfb8f5
Author:     Konstantin Belousov <kib@FreeBSD.org>
AuthorDate: 2026-05-24 11:48:45 +0000
Commit:     Konstantin Belousov <kib@FreeBSD.org>
CommitDate: 2026-05-28 12:38:25 +0000

    amd64: extract uiomove_mem() from memrw()
    
    Reviewed by:    markj
    Tested by:      aokblast
    Sponsored by:   The FreeBSD Foundation
    MFC after:      1 week
    Differential revision:  https://reviews.freebsd.org/D49566
---
 sys/amd64/amd64/mem.c         | 103 +++++-------------------------------------
 sys/amd64/amd64/uio_machdep.c |  96 +++++++++++++++++++++++++++++++++++++++
 sys/amd64/include/md_var.h    |   6 +++
 3 files changed, 113 insertions(+), 92 deletions(-)

diff --git a/sys/amd64/amd64/mem.c b/sys/amd64/amd64/mem.c
index ab1e6cde6cd5..7d1f0f42d01c 100644
--- a/sys/amd64/amd64/mem.c
+++ b/sys/amd64/amd64/mem.c
@@ -61,10 +61,6 @@
 #include <machine/specialreg.h>
 #include <machine/vmparam.h>
 
-#include <vm/vm.h>
-#include <vm/pmap.h>
-#include <vm/vm_extern.h>
-
 #include <machine/memdev.h>
 
 /*
@@ -72,99 +68,22 @@
  */
 MALLOC_DEFINE(M_MEMDESC, "memdesc", "memory range descriptors");
 
-/* ARGSUSED */
 int
 memrw(struct cdev *dev, struct uio *uio, int flags)
 {
-	struct iovec *iov;
-	void *p, *vd;
-	ssize_t orig_resid;
-	vm_prot_t prot;
-	u_long v;
-	u_int c;
-	int error;
-
-	error = 0;
-	orig_resid = uio->uio_resid;
-	while (uio->uio_resid > 0 && error == 0) {
-		iov = uio->uio_iov;
-		if (iov->iov_len == 0) {
-			uio->uio_iov++;
-			uio->uio_iovcnt--;
-			if (uio->uio_iovcnt < 0)
-				panic("memrw");
-			continue;
-		}
-		v = uio->uio_offset;
-		c = ulmin(iov->iov_len, PAGE_SIZE - (u_int)(v & PAGE_MASK));
-
-		switch (dev2unit(dev)) {
-		case CDEV_MINOR_KMEM:
-			/*
-			 * Since c is clamped to be less or equal than
-			 * PAGE_SIZE, the uiomove() call does not
-			 * access past the end of the direct map.
-			 */
-			if (v >= kva_layout.dmap_low &&
-			    v < kva_layout.dmap_high) {
-				error = uiomove((void *)v, c, uio);
-				break;
-			}
-
-			switch (uio->uio_rw) {
-			case UIO_READ:
-				prot = VM_PROT_READ;
-				break;
-			case UIO_WRITE:
-				prot = VM_PROT_WRITE;
-				break;
-			}
+	enum uiomove_mem_req req;
 
-			if (!kernacc((void *)v, c, prot)) {
-				error = EFAULT;
-				break;
-			}
-
-			/*
-			 * If the extracted address is not accessible
-			 * through the direct map, then we make a
-			 * private (uncached) mapping because we can't
-			 * depend on the existing kernel mapping
-			 * remaining valid until the completion of
-			 * uiomove().
-			 *
-			 * XXX We cannot provide access to the
-			 * physical page 0 mapped into KVA.
-			 */
-			v = pmap_extract(kernel_pmap, v);
-			if (v == 0) {
-				error = EFAULT;
-				break;
-			}
-			/* FALLTHROUGH */
-		case CDEV_MINOR_MEM:
-			if (v < dmaplimit) {
-				vd = PHYS_TO_DMAP(v);
-				error = uiomove(vd, c, uio);
-				break;
-			}
-			if (v > cpu_getmaxphyaddr()) {
-				error = EFAULT;
-				break;
-			}
-			p = pmap_mapdev(v, PAGE_SIZE);
-			error = uiomove(p, c, uio);
-			pmap_unmapdev(p, PAGE_SIZE);
-			break;
-		}
+	switch (dev2unit(dev)) {
+	case CDEV_MINOR_KMEM:
+		req = UIO_MEM_KMEM;
+		break;
+	case CDEV_MINOR_MEM:
+		req = UIO_MEM_MEM;
+		break;
+	default:
+		__unreachable();
 	}
-	/*
-	 * Don't return error if any byte was written.  Read and write
-	 * can return error only if no i/o was performed.
-	 */
-	if (uio->uio_resid != orig_resid)
-		error = 0;
-	return (error);
+	return (uiomove_mem(req, uio));
 }
 
 /*
diff --git a/sys/amd64/amd64/uio_machdep.c b/sys/amd64/amd64/uio_machdep.c
index 16915bccf9f5..11e6ad2b1da9 100644
--- a/sys/amd64/amd64/uio_machdep.c
+++ b/sys/amd64/amd64/uio_machdep.c
@@ -44,9 +44,11 @@
 #include <sys/uio.h>
 
 #include <vm/vm.h>
+#include <vm/vm_extern.h>
 #include <vm/vm_page.h>
 
 #include <machine/vmparam.h>
+#include <machine/md_var.h>
 
 /*
  * Implement uiomove(9) from physical memory using the direct map to
@@ -141,3 +143,97 @@ out:
 		td->td_pflags &= ~TDP_DEADLKTREAT;
 	return (error);
 }
+
+int
+uiomove_mem(enum uiomove_mem_req req, struct uio *uio)
+{
+	struct iovec *iov;
+	void *p, *vd;
+	ssize_t orig_resid;
+	vm_prot_t prot;
+	u_long v;
+	u_int c;
+	int error;
+
+	error = 0;
+	orig_resid = uio->uio_resid;
+	while (uio->uio_resid > 0 && error == 0) {
+		iov = uio->uio_iov;
+		if (iov->iov_len == 0) {
+			uio->uio_iov++;
+			uio->uio_iovcnt--;
+			if (uio->uio_iovcnt < 0)
+				panic("memrw");
+			continue;
+		}
+		v = uio->uio_offset;
+		c = ulmin(iov->iov_len, PAGE_SIZE - (u_int)(v & PAGE_MASK));
+
+		switch (req) {
+		case UIO_MEM_KMEM:
+			/*
+			 * Since c is clamped to be less or equal than
+			 * PAGE_SIZE, the uiomove() call does not
+			 * access past the end of the direct map.
+			 */
+			if (v >= kva_layout.dmap_low &&
+			    v < kva_layout.dmap_high) {
+				error = uiomove((void *)v, c, uio);
+				break;
+			}
+
+			switch (uio->uio_rw) {
+			case UIO_READ:
+				prot = VM_PROT_READ;
+				break;
+			case UIO_WRITE:
+				prot = VM_PROT_WRITE;
+				break;
+			}
+
+			if (!kernacc((void *)v, c, prot)) {
+				error = EFAULT;
+				break;
+			}
+
+			/*
+			 * If the extracted address is not accessible
+			 * through the direct map, then we make a
+			 * private (uncached) mapping because we can't
+			 * depend on the existing kernel mapping
+			 * remaining valid until the completion of
+			 * uiomove().
+			 *
+			 * XXX We cannot provide access to the
+			 * physical page 0 mapped into KVA.
+			 */
+			v = pmap_extract(kernel_pmap, v);
+			if (v == 0) {
+				error = EFAULT;
+				break;
+			}
+			/* FALLTHROUGH */
+		case UIO_MEM_MEM:
+			if (v < dmaplimit) {
+				vd = PHYS_TO_DMAP(v);
+				error = uiomove(vd, c, uio);
+				break;
+			}
+			if (v > cpu_getmaxphyaddr()) {
+				error = EFAULT;
+				break;
+			}
+			p = pmap_mapdev(v, PAGE_SIZE);
+			error = uiomove(p, c, uio);
+			pmap_unmapdev(p, PAGE_SIZE);
+			break;
+		}
+	}
+	/*
+	 * Don't return error if any byte was written.  Read and write
+	 * can return error only if no i/o was performed.
+	 */
+	if (uio->uio_resid != orig_resid)
+		error = 0;
+	return (error);
+}
diff --git a/sys/amd64/include/md_var.h b/sys/amd64/include/md_var.h
index 4b98c5d8c418..0e8fe916490b 100644
--- a/sys/amd64/include/md_var.h
+++ b/sys/amd64/include/md_var.h
@@ -106,6 +106,12 @@ void	wrmsr_early_safe_start(void);
 void	wrmsr_early_safe_end(void);
 int	wrmsr_early_safe(u_int msr, uint64_t data);
 
+enum uiomove_mem_req {
+	UIO_MEM_KMEM = 101,
+	UIO_MEM_MEM,
+};
+int uiomove_mem(enum uiomove_mem_req req, struct uio *uio);
+
 #endif /* !_MACHINE_MD_VAR_H_ */
 
 #endif /* __i386__ */