[PATCH 23/40] lmb: add a flags parameter to the API's
Sughosh Ganu
sughosh.ganu at linaro.org
Wed Aug 14 10:13:24 CEST 2024
On Fri, 9 Aug 2024 at 21:28, Simon Glass <sjg at chromium.org> wrote:
>
> Hi Sughosh,
>
> On Fri, 9 Aug 2024 at 02:25, Sughosh Ganu <sughosh.ganu at linaro.org> wrote:
> >
> > On Thu, 8 Aug 2024 at 19:58, Simon Glass <sjg at chromium.org> wrote:
> > >
> > > Hi Sughosh,
> > >
> > > On Wed, 7 Aug 2024 at 00:32, Sughosh Ganu <sughosh.ganu at linaro.org> wrote:
> > > >
> > > > On Wed, 7 Aug 2024 at 03:21, Simon Glass <sjg at chromium.org> wrote:
> > > > >
> > > > > Hi Sughosh,
> > > > >
> > > > > On Mon, 5 Aug 2024 at 05:55, Sughosh Ganu <sughosh.ganu at linaro.org> wrote:
> > > > > >
> > > > > > On Mon, 29 Jul 2024 at 20:56, Simon Glass <sjg at chromium.org> wrote:
> > > > > > >
> > > > > > > Hi Sughosh,
> > > > > > >
> > > > > > > On Mon, 29 Jul 2024 at 02:40, Sughosh Ganu <sughosh.ganu at linaro.org> wrote:
> > > > > > > >
> > > > > > > > On Fri, 26 Jul 2024 at 05:02, Simon Glass <sjg at chromium.org> wrote:
> > > > > > > > >
> > > > > > > > > Hi Sughosh,
> > > > > > > > >
> > > > > > > > > On Wed, 24 Jul 2024 at 00:04, Sughosh Ganu <sughosh.ganu at linaro.org> wrote:
> > > > > > > > > >
> > > > > > > > > > Add a flags parameter to the LMB API functions. The parameter can then
> > > > > > > > > > be used to pass any other type of reservations or allocations needed
> > > > > > > > > > by the callers. These will be used in a subsequent set of changes for
> > > > > > > > > > allocation requests coming from the EFI subsystem.
> > > > > > > > > >
> > > > > > > > > > Signed-off-by: Sughosh Ganu <sughosh.ganu at linaro.org>
> > > > > > > > > > ---
> > > > > > > > > > Changes since rfc: New patch
> > > > > > > > > >
> > > > > > > > > > arch/arm/mach-apple/board.c | 17 ++--
> > > > > > > > > > arch/arm/mach-snapdragon/board.c | 2 +-
> > > > > > > > > > arch/arm/mach-stm32mp/dram_init.c | 4 +-
> > > > > > > > > > arch/powerpc/cpu/mpc85xx/mp.c | 2 +-
> > > > > > > > > > arch/powerpc/lib/bootm.c | 2 +-
> > > > > > > > > > board/xilinx/common/board.c | 4 +-
> > > > > > > > > > boot/bootm.c | 5 +-
> > > > > > > > > > boot/image-board.c | 15 ++-
> > > > > > > > > > boot/image-fdt.c | 15 +--
> > > > > > > > > > cmd/booti.c | 2 +-
> > > > > > > > > > cmd/bootz.c | 2 +-
> > > > > > > > > > cmd/load.c | 4 +-
> > > > > > > > > > drivers/iommu/apple_dart.c | 6 +-
> > > > > > > > > > drivers/iommu/sandbox_iommu.c | 6 +-
> > > > > > > > > > fs/fs.c | 2 +-
> > > > > > > > > > include/lmb.h | 23 ++---
> > > > > > > > > > lib/lmb.c | 48 ++++------
> > > > > > > > > > test/lib/lmb.c | 150 +++++++++++++++---------------
> > > > > > > > > > 18 files changed, 150 insertions(+), 159 deletions(-)
> > > > > > > > >
> > > > > > > > > This negates any code-size advantage of dropping the lmb parameter.
> > > > > > > > >
> > > > > > > > > All of these are LMB_NONE. Can we have a separate function (e.g.
> > > > > > > > > lmb_alloc_type()) for when we actually need to specify the type?
> > > > > > > >
> > > > > > > > We will be passing different values when we call the LMB API's from
> > > > > > > > the EFI allocation function. This is only adding a parameter to the
> > > > > > > > allocation API's, which I believe is better than adding separate
> > > > > > > > functions which take a flag parameter only to be called from the EFI
> > > > > > > > subsystem.
> > > > > > >
> > > > > > > No i believe it is worse, unless there are a lot of such functions.
> > > > > > > The flags are a special case, not the common case.
> > > > > >
> > > > > > I have done some size impact tests on the two scenarios, one where we
> > > > > > have a common set of lmb allocation API functions, with an added flags
> > > > > > parameter, and second where we have separate API's to be called from
> > > > > > the EFI memory module. I have put out the results of the size impact
> > > > > > [1].
> > > > > >
> > > > > > You will see that with common API's, we are not losing much even on
> > > > > > boards with EFI_LOADER disabled. But otoh, on boards which have
> > > > > > EFI_LOADER enabled, the gains are pretty significant. I believe we
> > > > > > should reconsider using a common LMB API with the flags parameter.
> > > > >
> > > > > Thanks for looking at it.
> > > > >
> > > > > Did you do special versions of just lmb_alloc() and lmb_add() which
> > > > > call the flags versions? It seems that there is no size advantage with
> > > > > EFI_LOADER and only a small one with !EFI_LOADER. Can you please point
> > > > > me to the code?
> > > >
> > > > For the separate API version, I introduced new versions
> > > > lmb_alloc_flags(), lmb_alloc_base_flags(), lmb_alloc_addr_flags() and
> > > > lmb_free_flags(), which are being called from the EFI memory module. I
> > > > have pushed the two branches [1] [2] on my github. Please take a look.
> > > >
> > > > Btw, both these branches are based on your v5 of the alist patches,
> > > > and also incorporate the stack based implementation for running the
> > > > lmb tests. So except for either having common API's, or not, there are
> > > > no other differences between the two. Thanks.
> > >
> > > Thanks for the info.
> > >
> > > The non-flags functions can call the flags functions, so that you
> > > don't create a new code path. Something like this:
> > >
> > > diff --git a/lib/lmb.c b/lib/lmb.c
> > > index 726e6c38227..0a251c587fe 100644
> > > --- a/lib/lmb.c
> > > +++ b/lib/lmb.c
> > > @@ -528,7 +528,7 @@ long lmb_free_flags(phys_addr_t base, phys_size_t size,
> > >
> > > long lmb_free(phys_addr_t base, phys_size_t size)
> > > {
> > > - return __lmb_free(base, size);
> > > + return lmb_free_flags(base, size, LMB_NONE);
> > > }
> > >
> > > long lmb_reserve_flags(phys_addr_t base, phys_size_t size, enum
> > > lmb_flags flags)
> > > @@ -624,7 +624,7 @@ static phys_addr_t __lmb_alloc_base(phys_size_t
> > > size, ulong align,
> > >
> > > phys_addr_t lmb_alloc(phys_size_t size, ulong align)
> > > {
> > > - return lmb_alloc_base(size, align, LMB_ALLOC_ANYWHERE);
> > > + return lmb_alloc_flags(size, align, LMB_NONE);
> > > }
> > >
> > > phys_addr_t lmb_alloc_flags(phys_size_t size, ulong align, uint flags)
> > > @@ -635,15 +635,7 @@ phys_addr_t lmb_alloc_flags(phys_size_t size,
> > > ulong align, uint flags)
> > >
> > > phys_addr_t lmb_alloc_base(phys_size_t size, ulong align, phys_addr_t max_addr)
> > > {
> > > - phys_addr_t alloc;
> > > -
> > > - alloc = __lmb_alloc_base(size, align, max_addr, LMB_NONE);
> > > -
> > > - if (alloc == 0)
> > > - printf("ERROR: Failed to allocate 0x%lx bytes below 0x%lx.\n",
> > > - (ulong)size, (ulong)max_addr);
> > > -
> > > - return alloc;
> > > + return lmb_alloc_base_flags(size, align, max_addr, LMB_NONE);
> > > }
> > >
> > > phys_addr_t lmb_alloc_base_flags(phys_size_t size, ulong align,
> > > @@ -691,7 +683,7 @@ static phys_addr_t __lmb_alloc_addr(phys_addr_t
> > > base, phys_size_t size,
> > > */
> > > phys_addr_t lmb_alloc_addr(phys_addr_t base, phys_size_t size)
> > > {
> > > - return __lmb_alloc_addr(base, size, LMB_NONE);
> > > + return lmb_alloc_addr_flags(base, size, LMB_NONE);
> > > }
> > >
> > > phys_addr_t lmb_alloc_addr_flags(phys_addr_t base, phys_size_t size,
> > >
> > > But it only saves about 40 bytes on Thumb2. You can save another 16 by
> > > using the placeholder API:
> >
> > Can you please explain the issue that you see with having a common set
> > of API's with the flags parameter added? The way I see it, the API's
> > are already undergoing a change where we are removing the struct lmb
> > instance as a parameter from all the API functions. With the change
> > that I propose, we are simply replacing the lmb instance parameter
> > with the flags parameter. So arguably we are not adding any additional
> > size here. Also, like the size tests show, we get a pretty good size
> > benefit when the EFI_LOADER is enabled.
> >
> > So, if your argument is to keep the API's similar to their earlier
> > form, I think that they are undergoing a change in any case, so adding
> > the flags parameter is not so much of an issue. If there is any
> > problem that I am missing, I would like to understand that before we
> > go with separate API's. Thanks.
>
> I thought I explained this already, but perhaps not. We change APIs
> all the time, so that is not a problem.
>
> Almost all calls don't need to pass flags since it is LMB_NONE (which
> really should be 0, BTW, not BIT(0)). We already have
> lmb_reserve_flags() and lmb_reserve() to deal with this difference. So
> passing a parameter which is almost always the same is not helpful for
> code size.
Yes, in my earlier response, I did mention this aspect. The size
impact is not very high on non-EFI platforms, while pretty good with
platforms that enable EFI_LOADER. But since this is your view, I will
go with the separate API version so that we make progress.
>
> Outside the tests, only one place (boot/image-fdt.c) uses
> lmb_reserve_flags() - BTW some of these are using the flags version of
> the function but passing LMB_NONE.
>
> Here are the five functions:
>
> lmb_reserve
> lmb_alloc
> lmb_alloc_base
> lmb_alloc_addr
> lmb_free
>
> If some of them aren't worth having two versions, then I suppose we
> don't need them all. But note that if some of my EFI patches make it
> through code review, we won't need this circular relationship between
> EFI and lmb, so some of the 'flags' versions can be dropped again.
Your patch is tweaking the efi_allocate_pool() whereas the changes
that I am making are in the efi_allocate_pages(). So even if your
approach gets accepted, this will still be needed for
efi_allocate_pages() API.
>
> But EFI only even seems to pass LMB_NOOVERWRITE | LMB_NONOTIFY...?
>
> Part of my frustration with all of this is that I created an lmb
> cleanup series[1] nearly a year ago, which was either ignored or
> blocked (I'm not sure which). That series tidied up the code quite a
> lot and took much effort. I'm not sure if you even saw it?
I wasn't aware of these patches. I started looking into the LMB/EFI
memory management only a few months back.
>
> Finally, it would help the project if you could do some code reviews.
> For example, how about [2] and [3] - they are very much in your area.
Okay, will do. I will check the patches in detail, but I believe that
patch 2 looks fine, but I have concerns about using malloc for
efi_allocate_pool(). I will respond to the patch though. Thanks.
-sughosh
>
> Regards,
> Simon
>
> [1] https://patchwork.ozlabs.org/project/uboot/list/?series=371258&state=*
> [2] https://patchwork.ozlabs.org/project/uboot/list/?series=417669
> [3] https://patchwork.ozlabs.org/project/uboot/list/?series=418212
>
>
>
>
> >
> > -sughosh
> >
> > >
> > > diff --git a/lib/lmb.c b/lib/lmb.c
> > > index 0a251c587fe..f6c8f06629c 100644
> > > --- a/lib/lmb.c
> > > +++ b/lib/lmb.c
> > > @@ -416,13 +416,12 @@ static long lmb_add_region_flags(struct alist
> > > *lmb_rgn_lst, phys_addr_t base,
> > > if (coalesced)
> > > return coalesced;
> > >
> > > - if (alist_full(lmb_rgn_lst) &&
> > > - !alist_expand_by(lmb_rgn_lst, lmb_rgn_lst->alloc))
> > > + if (!alist_add_placeholder(lmb_rgn_lst))
> > > return -1;
> > > rgn = lmb_rgn_lst->data;
> > >
> > > /* Couldn't coalesce the LMB, so add it to the sorted table. */
> > > - for (i = lmb_rgn_lst->count; i >= 0; i--) {
> > > + for (i = lmb_rgn_lst->count - 1; i >= 0; i--) {
> > > if (i && base < rgn[i - 1].base) {
> > > rgn[i] = rgn[i - 1];
> > > } else {
> > > @@ -433,8 +432,6 @@ static long lmb_add_region_flags(struct alist
> > > *lmb_rgn_lst, phys_addr_t base,
> > > }
> > > }
> > >
> > > - lmb_rgn_lst->count++;
> > > -
> > > return 0;
> > > }
> > >
> > > @@ -444,7 +441,6 @@ static long lmb_add_region(struct alist
> > > *lmb_rgn_lst, phys_addr_t base,
> > > return lmb_add_region_flags(lmb_rgn_lst, base, size, LMB_NONE);
> > > }
> > >
> > > -/* This routine may be called with relocation disabled. */
> > > long lmb_add(phys_addr_t base, phys_size_t size)
> > > {
> > > long ret;
> > >
> > > --
> > > 2.34.1
> > >
> > > (patches are a bit rough, but I didn't think it worth sending them to
> > > the ML as real patches)
> > >
> > > If I am correct and we don't need to publish events, then that will
> > > save a little more space.
> > >
> > > Regards,
> > > Simon
> > >
> > > >
> > > > -sughosh
> > > >
> > > > [1] - https://github.com/sughoshg/u-boot/tree/lmb_efi_common_apis_nrfc_v2
> > > > [2] - https://github.com/sughoshg/u-boot/tree/lmb_efi_separate_flags_apis_nrfc_v2
> > > >
> > > > >
> > > > > Regards,
> > > > > Simon
> > > > >
> > > > >
> > > > > >
> > > > > > [1] - https://gist.github.com/sughoshg/a20207f26e19238fef86f710134d6efd
> > > > > >
> > > > > > >
> > > > > > > Regards,
> > > > > > > SImon
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