Date: Mon, 6 Nov 2023 16:55:14 GMT From: Mitchell Horne <mhorne@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: c1e21468213e - main - pmap_kextract(9): some additions Message-ID: <202311061655.3A6GtElF074868@gitrepo.freebsd.org>
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The branch main has been updated by mhorne: URL: https://cgit.FreeBSD.org/src/commit/?id=c1e21468213e3ae35c5302f94472f1d996d530cd commit c1e21468213e3ae35c5302f94472f1d996d530cd Author: Mitchell Horne <mhorne@FreeBSD.org> AuthorDate: 2023-11-06 16:54:18 +0000 Commit: Mitchell Horne <mhorne@FreeBSD.org> CommitDate: 2023-11-06 16:54:45 +0000 pmap_kextract(9): some additions Mainly, provide a little more detail on the caller's responsibilities. Suggested by: kib, jhb Reviewed by: kib, markj Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D42458 --- share/man/man9/pmap_kextract.9 | 18 +++++++++++++++--- 1 file changed, 15 insertions(+), 3 deletions(-) diff --git a/share/man/man9/pmap_kextract.9 b/share/man/man9/pmap_kextract.9 index 40008a1bc96c..a93bbc70b351 100644 --- a/share/man/man9/pmap_kextract.9 +++ b/share/man/man9/pmap_kextract.9 @@ -31,9 +31,21 @@ The function retrieves the underlying physical memory address corresponding to the given kernel virtual address .Fa va . -The value of +The caller is responsible for ensuring that .Fa va -must belong to a valid mapping in the kernel address space. +belongs to a valid mapping in the kernel address space. +The returned physical address is only meaningful as long as the mapping remains +stable, so the caller must also have some knowledge or guarantee of the +mapping's lifetime. +For example, it is invalid to call +.Fn pmap_kextract +with the address of a malloc'd object while there is a possibility for that +object to be freed concurrently. +.Pp +Unlike +.Xr pmap_extract 9 , +.Fn pmap_kextract +is safe to be called from any context; it has no internal locking or sleep. .Pp .Fn vtophys is an alias for @@ -42,7 +54,7 @@ and behaves identically. .Sh RETURN VALUES The .Fn pmap_kextract -function returns the address of physical memory mapped at the kernel +function returns the physical address of memory mapped at the kernel virtual address .Fa va . .Pp
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