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diff --git a/share/man/man9/pmap_kextract.9 b/share/man/man9/pmap_kextract.9 new file mode 100644 index 000000000000..a93bbc70b351 --- /dev/null +++ b/share/man/man9/pmap_kextract.9 @@ -0,0 +1,77 @@ +.\" +.\" SPDX-License-Identifier: BSD-2-Clause +.\" +.\" Copyright (c) 2023 The FreeBSD Foundation +.\" +.\" This manual page was written by Mina Galić <FreeBSD@igalic.co> under +.\" sponsorship from the FreeBSD Foundation. +.\" +.Dd October 16, 2023 +.Dt PMAP_KEXTRACT 9 +.Os +.Sh NAME +.Nm pmap_kextract , +.Nm vtophys +.Nd extract a physical address from the kernel page table +.Sh SYNOPSIS +.In sys/param.h +.In vm/vm.h +.In vm/pmap.h +.Ft vm_paddr_t +.Fo pmap_kextract +.Fa "vm_offset_t va" +.Fc +.Ft vm_paddr_t +.Fo vtophys +.Fa "vm_offset_t va" +.Fc +.Sh DESCRIPTION +The +.Fn pmap_kextract +function retrieves the underlying physical memory address corresponding to the +given kernel virtual address +.Fa va . +The caller is responsible for ensuring that +.Fa va +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 +.Fn pmap_kextract +and behaves identically. +.Sh RETURN VALUES +The +.Fn pmap_kextract +function returns the physical address of memory mapped at the kernel +virtual address +.Fa va . +.Pp +.Fn pmap_kextract +generally does not fail. +However, if supplied with an illegitimate value for +.Fa va , +the function may return zero, an invalid non-zero value, or call +.Xr panic 9 . +.Sh SEE ALSO +.Xr pmap 9 , +.Xr pmap_extract 9 +.Sh AUTHORS +.An -nosplit +This manual page was written by +.An Mina Galić Aq Mt FreeBSD@igalic.co , +based on the +.Xr pmap_extract 9 +page written by +.An Bruce M Simpson Aq Mt bms@spc.org . |