Date: Thu, 28 May 2026 12:38:33 +0000 From: Konstantin Belousov <kib@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: 7b2702ee25f5 - main - sys: add safe_read(9) Message-ID: <6a183749.45808.5d99f3ce@gitrepo.freebsd.org>
index | next in thread | raw e-mail
The branch main has been updated by kib: URL: https://cgit.FreeBSD.org/src/commit/?id=7b2702ee25f5230011fa7f8f650b65b37248fcca commit 7b2702ee25f5230011fa7f8f650b65b37248fcca Author: Konstantin Belousov <kib@FreeBSD.org> AuthorDate: 2025-03-29 17:17:01 +0000 Commit: Konstantin Belousov <kib@FreeBSD.org> CommitDate: 2026-05-28 12:38:25 +0000 sys: add safe_read(9) The MD function with MI interface to provide a way to read arbitrary (canonical) KVA. amd64 only for now. 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/machdep.c | 18 ++++++++++++++++++ sys/sys/systm.h | 8 ++++++++ 2 files changed, 26 insertions(+) diff --git a/sys/amd64/amd64/machdep.c b/sys/amd64/amd64/machdep.c index dbad85096a1d..db2fd5927f7f 100644 --- a/sys/amd64/amd64/machdep.c +++ b/sys/amd64/amd64/machdep.c @@ -1852,6 +1852,24 @@ wrmsr_early_safe_end(void) memset_early(gpf_descr, 0, sizeof(*gpf_descr)); } +int +safe_read(vm_offset_t addr, char *valp) +{ + struct uio uio; + struct iovec iov; + + iov.iov_base = valp; + iov.iov_len = 1; + uio.uio_offset = addr; + uio.uio_iov = &iov; + uio.uio_iovcnt = 1; + uio.uio_resid = 1; + uio.uio_segflg = UIO_SYSSPACE; + uio.uio_rw = UIO_READ; + uio.uio_td = NULL; + return (uiomove_mem(UIO_MEM_KMEM, &uio)); +} + #ifdef KDB /* diff --git a/sys/sys/systm.h b/sys/sys/systm.h index 7f655b48ba08..88c25f06e0cb 100644 --- a/sys/sys/systm.h +++ b/sys/sys/systm.h @@ -553,6 +553,14 @@ void intr_prof_stack_use(struct thread *td, struct trapframe *frame); void counted_warning(unsigned *counter, const char *msg); +/* + * Safely read one byte of kernel memory at address addr, placing the + * value into *valp. Returns 0 on success, EFAULT if read was + * impossible, e.g. due to the address not being mapped or not having + * necessary permissions. + */ +int safe_read(vm_offset_t addr, char *valp); + /* * APIs to manage deprecation and obsolescence. */home | help
Want to link to this message? Use this
URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?6a183749.45808.5d99f3ce>