Re: git: 74e4a8d208f0 - main - pmap: add pmap_kextract(9) man page
- In reply to: Mitchell Horne : "Re: git: 74e4a8d208f0 - main - pmap: add pmap_kextract(9) man page"
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Date: Sat, 14 Oct 2023 18:20:08 UTC
On Sat, Oct 14, 2023 at 02:34:58PM -0300, Mitchell Horne wrote:
> On 10/14/23 10:28, Konstantin Belousov wrote:
> > On Fri, Oct 13, 2023 at 06:27:33PM +0000, Mitchell Horne wrote:
> > > The branch main has been updated by mhorne:
> > >
> > > URL: https://cgit.FreeBSD.org/src/commit/?id=74e4a8d208f0b3cf2525e3786f3efba71fcdb752
> > >
> > > commit 74e4a8d208f0b3cf2525e3786f3efba71fcdb752
> > > Author: Mina Galić <freebsd@igalic.co>
> > > AuthorDate: 2023-08-23 00:12:49 +0000
> > > Commit: Mitchell Horne <mhorne@FreeBSD.org>
> > > CommitDate: 2023-10-13 18:27:24 +0000
> > >
> > > pmap: add pmap_kextract(9) man page
> > > Add a man page for pmap_kextract(9), with alias to vtophys(9). This man
> > > page is based on pmap_extract(9).
> > > Add it as cross reference in pmap(9), and add comments above the
> > > function implementations.
> > > Co-authored-by: Graham Perrin <grahamperrin@gmail.com>
> > > Co-authored-by: mhorne
> > > Sponsored by: The FreeBSD Foundation
> > > Pull Request: https://github.com/freebsd/freebsd-src/pull/827
> > > ---
> > > share/man/man9/Makefile | 2 ++
> > > share/man/man9/pmap.9 | 1 +
> > > share/man/man9/pmap_kextract.9 | 65 ++++++++++++++++++++++++++++++++++++++++++
> > > sys/amd64/amd64/pmap.c | 8 +++++-
> > > sys/arm64/arm64/pmap.c | 6 ++++
> > > sys/riscv/riscv/pmap.c | 6 ++++
> > > 6 files changed, 87 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/share/man/man9/Makefile b/share/man/man9/Makefile
> > > index 0b56a47db332..6768f52a38d6 100644
> > > --- a/share/man/man9/Makefile
> > > +++ b/share/man/man9/Makefile
> > > @@ -268,6 +268,7 @@ MAN= accept_filter.9 \
> > > pmap_copy.9 \
> > > pmap_enter.9 \
> > > pmap_extract.9 \
> > > + pmap_kextract.9 \
> > > pmap_growkernel.9 \
> > > pmap_init.9 \
> > > pmap_is_modified.9 \
> > > @@ -1807,6 +1808,7 @@ MLINKS+=PHOLD.9 PRELE.9 \
> > > PHOLD.9 PROC_ASSERT_NOT_HELD.9
> > > MLINKS+=pmap_copy.9 pmap_copy_page.9
> > > MLINKS+=pmap_extract.9 pmap_extract_and_hold.9
> > > +MLINKS+=pmap_kextract.9 vtophys.9
> > > MLINKS+=pmap_init.9 pmap_init2.9
> > > MLINKS+=pmap_is_modified.9 pmap_ts_referenced.9
> > > MLINKS+=pmap_pinit.9 pmap_pinit0.9 \
> > > diff --git a/share/man/man9/pmap.9 b/share/man/man9/pmap.9
> > > index 3f6a0f63c264..db27fe880afc 100644
> > > --- a/share/man/man9/pmap.9
> > > +++ b/share/man/man9/pmap.9
> > > @@ -97,6 +97,7 @@ operation.
> > > .Xr pmap_init2 9 ,
> > > .Xr pmap_is_modified 9 ,
> > > .Xr pmap_is_prefaultable 9 ,
> > > +.Xr pmap_kextract 9 ,
> > > .Xr pmap_map 9 ,
> > > .Xr pmap_mincore 9 ,
> > > .Xr pmap_object_init_pt 9 ,
> > > diff --git a/share/man/man9/pmap_kextract.9 b/share/man/man9/pmap_kextract.9
> > > new file mode 100644
> > > index 000000000000..dd73446648f2
> > > --- /dev/null
> > > +++ b/share/man/man9/pmap_kextract.9
> > > @@ -0,0 +1,65 @@
> > > +.\"
> > > +.\" 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 August 24, 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
> > Line too long.
> >
> > > +.Fa va .
> > > +The value of
> > > +.Fa va
> > > +must correlate to an active mapping in the kernel address space.
> > What does it mean 'correlate'?
> >
>
> 'correlate' means that the relationship exists in both directions. We could
> describe an address as "belonging to" a VA->PA mapping, or we could say that
> an address "posseses" such a mapping. Maybe you have a strong opinion on why
> one is incorrect.
>
> Since 'correlate' is not established terminology, and needlessly confusing,
> I can simplify it to:
>
> "The value of va must belong to an active mapping in..."
s/active/valid/ then it sounds as the established terminology.
>
> If you have a different suggestion, let me know.
>
> > > +.Pp
> > > +.Fn vtophys
> > > +is an alias for
> > > +.Fn pmap_kextract
> > > +and behaves identically.
> > > +.Sh RETURN VALUES
> > > +The
> > > +.Fn pmap_kextract
> > > +function will return the physical address
> > > +.Pq Vt vm_paddr_t
> > > +associated with the kernel virtual address
> > and 'associated'?
> >
> > The function returns address of physical memory mapped at the supplied
> > kernel virtual address.
> >
>
> Sure, this is more accurate.
>
> > > +.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 .
> > > diff --git a/sys/amd64/amd64/pmap.c b/sys/amd64/amd64/pmap.c
> > > index ff83d8749313..8c438cfb4639 100644
> > > --- a/sys/amd64/amd64/pmap.c
> > > +++ b/sys/amd64/amd64/pmap.c
> > > @@ -3846,7 +3846,7 @@ pmap_flush_cache_phys_range(vm_paddr_t spa, vm_paddr_t epa, vm_memattr_t mattr)
> > > * Extract the physical page address associated
> > > * with the given map/virtual_address pair.
> > > */
> > > -vm_paddr_t
> > > +vm_paddr_t
> > > pmap_extract(pmap_t pmap, vm_offset_t va)
> > > {
> > > pdp_entry_t *pdpe;
> > > @@ -3933,6 +3933,12 @@ out:
> > > return (m);
> > > }
> > > +/*
> > > + * Routine: pmap_kextract
> > > + * Function:
> > > + * Extract the physical page address associated with the given kernel
> > > + * virtual address.
> > > + */
> > > vm_paddr_t
> > > pmap_kextract(vm_offset_t va)
> > > {
> > > diff --git a/sys/arm64/arm64/pmap.c b/sys/arm64/arm64/pmap.c
> > > index 6f2afa0b98a3..8c2c6f9d7b81 100644
> > > --- a/sys/arm64/arm64/pmap.c
> > > +++ b/sys/arm64/arm64/pmap.c
> > > @@ -1949,6 +1949,12 @@ pmap_klookup(vm_offset_t va, vm_paddr_t *pa)
> > > return (true);
> > > }
> > > +/*
> > > + * Routine: pmap_kextract
> > > + * Function:
> > > + * Extract the physical page address associated with the given kernel
> > > + * virtual address.
> > > + */
> > > vm_paddr_t
> > > pmap_kextract(vm_offset_t va)
> > > {
> > > diff --git a/sys/riscv/riscv/pmap.c b/sys/riscv/riscv/pmap.c
> > > index 49ee54b37918..66054898b281 100644
> > > --- a/sys/riscv/riscv/pmap.c
> > > +++ b/sys/riscv/riscv/pmap.c
> > > @@ -970,6 +970,12 @@ pmap_extract_and_hold(pmap_t pmap, vm_offset_t va, vm_prot_t prot)
> > > return (m);
> > > }
> > > +/*
> > > + * Routine: pmap_kextract
> > > + * Function:
> > > + * Extract the physical page address associated with the given kernel
> > > + * virtual address.
> > > + */
> > > vm_paddr_t
> > > pmap_kextract(vm_offset_t va)
> > > {