[RFC PATCH 15/31] efi_memory: add an event handler to update memory map
Sughosh Ganu
sughosh.ganu at linaro.org
Wed Jun 12 09:11:51 CEST 2024
On Wed, 12 Jun 2024 at 12:16, Ilias Apalodimas
<ilias.apalodimas at linaro.org> wrote:
>
> On Mon, 10 Jun 2024 at 18:54, Simon Glass <sjg at chromium.org> wrote:
> >
> > Hi,
> >
> > On Mon, 10 Jun 2024 at 09:42, Sughosh Ganu <sughosh.ganu at linaro.org> wrote:
> > >
> > > On Mon, 10 Jun 2024 at 20:47, Heinrich Schuchardt <xypron.glpk at gmx.de> wrote:
> > > >
> > > > On 07.06.24 20:52, Sughosh Ganu wrote:
> > > > > There are events that would be used to notify other interested modules
> > > > > of any changes in available and occupied memory. This would happen
> > > > > when a module allocates or reserves memory, or frees up memory. These
> > > >
> > > > I am worried about the "frees up memory" case.
> > > >
> > > > When LMB frees memory we cannot add it back to EFI conventional memory
> > > > as there might still be a file image lingering around that EFI should
> > > > not overwrite. It has to stay marked as EfiLoaderCode or EfiLoaderData.
> > >
> > > So here is my basic doubt. Why would LMB free up memory if it still
> > > has a valid image. If that is the case, the lmb_free API should not be
> > > called?
> > >
> > > -sughosh
> > >
> > >
> > > >
> > > > How do you ensure that if a region reserved by LMB notification as
> > > > EfiLoaderData is coalesced with some other allocation LMB is not
> > > > requested to mark the coalesced region as reserved?
> > > >
> > > > @Tom
> > > >
> > > > Clinging to the existing logic that you can do anything when loading
> > > > files is obviously leading us into coding hell.
> > > >
> > > > If somebody wants to load two images into the same location, he should
> > > > be forced to unload the first image. This will allow us to have a single
> > > > memory management system.
> >
> > It seems we really shouldn't use the words 'allocate' and 'free' when
> > talking about LMB. They are simply reservations.
>
> Correct and while at it can we please make the code less confusing to
> read. What we today mark as reserved isnt even trully reserved as it
> can be overwritten.
> struct lmb_region memory -> available memory we added on LMB. That's fine
> struct lmb_region reserved -> can we rename this to 'used' and rename
> LMB_NOOVERWRITE to LMB_RESERVED?
Okay. Will incorporate this change in the next version. Thanks.
-sughosh
>
> Thanks
> /Ilias
>
> > I believe we have got
> > into this situation due to an assumption that these two things are the
> > same, but in U-Boot they certainly are not. LMB is a very lighweight
> > and temporary reservation system to be used for a single boot process.
> >
> > Regards,
> > Simon
> >
> >
> > > >
> > > > Best regards
> > > >
> > > > Heinrich
> > > >
> > > > > changes in memory map should be notified to other interested modules
> > > > > so that the allocated memory does not get overwritten. Add an event
> > > > > handler in the EFI memory module to update the EFI memory map
> > > > > accordingly when such changes happen. As a consequence, any subsequent
> > > > > memory request would honour the updated memory map and only available
> > > > > memory would be allocated from.
> > > > >
> > > > > Signed-off-by: Sughosh Ganu <sughosh.ganu at linaro.org>
> > > > > ---
> > > > > lib/efi_loader/efi_memory.c | 70 ++++++++++++++++++++++++++++++-------
> > > > > 1 file changed, 58 insertions(+), 12 deletions(-)
> > > > >
> > > > > diff --git a/lib/efi_loader/efi_memory.c b/lib/efi_loader/efi_memory.c
> > > > > index 435e580fb3..93244161b0 100644
> > > > > --- a/lib/efi_loader/efi_memory.c
> > > > > +++ b/lib/efi_loader/efi_memory.c
> > > > > @@ -73,6 +73,10 @@ struct efi_pool_allocation {
> > > > > #if CONFIG_IS_ENABLED(MEM_MAP_UPDATE_NOTIFY)
> > > > > extern bool is_addr_in_ram(uintptr_t addr);
> > > > >
> > > > > +static efi_status_t __efi_add_memory_map_pg(u64 start, u64 pages,
> > > > > + int memory_type,
> > > > > + bool overlap_only_ram);
> > > > > +
> > > > > static void efi_map_update_notify(u64 addr, u64 size, u8 op)
> > > > > {
> > > > > struct event_efi_mem_map_update efi_map = {0};
> > > > > @@ -84,6 +88,34 @@ static void efi_map_update_notify(u64 addr, u64 size, u8 op)
> > > > > if (is_addr_in_ram((uintptr_t)addr))
> > > > > event_notify(EVT_EFI_MEM_MAP_UPDATE, &efi_map, sizeof(efi_map));
> > > > > }
> > > > > +
> > > > > +static int lmb_mem_map_update_sync(void *ctx, struct event *event)
> > > > > +{
> > > > > + u8 op;
> > > > > + u64 addr;
> > > > > + u64 pages;
> > > > > + efi_status_t status;
> > > > > + struct event_lmb_map_update *lmb_map = &event->data.lmb_map;
> > > > > +
> > > > > + addr = (uintptr_t)map_sysmem(lmb_map->base, 0);
> > > > > + pages = efi_size_in_pages(lmb_map->size + (addr & EFI_PAGE_MASK));
> > > > > + op = lmb_map->op;
> > > > > + addr &= ~EFI_PAGE_MASK;
> > > > > +
> > > > > + if (op != MAP_OP_RESERVE && op != MAP_OP_FREE) {
> > > > > + log_debug("Invalid map update op received (%d)\n", op);
> > > > > + return -1;
> > > > > + }
> > > > > +
> > > > > + status = __efi_add_memory_map_pg(addr, pages,
> > > > > + op == MAP_OP_FREE ?
> > > > > + EFI_CONVENTIONAL_MEMORY :
> > > > > + EFI_BOOT_SERVICES_DATA,
> > > > > + true);
> > > > > +
> > > > > + return status == EFI_SUCCESS ? 0 : -1;
> > > > > +}
> > > > > +EVENT_SPY_FULL(EVT_LMB_MAP_UPDATE, lmb_mem_map_update_sync);
> > > > > #endif /* MEM_MAP_UPDATE_NOTIFY */
> > > > >
> > > > > /**
> > > > > @@ -275,18 +307,9 @@ static s64 efi_mem_carve_out(struct efi_mem_list *map,
> > > > > return EFI_CARVE_LOOP_AGAIN;
> > > > > }
> > > > >
> > > > > -/**
> > > > > - * efi_add_memory_map_pg() - add pages to the memory map
> > > > > - *
> > > > > - * @start: start address, must be a multiple of EFI_PAGE_SIZE
> > > > > - * @pages: number of pages to add
> > > > > - * @memory_type: type of memory added
> > > > > - * @overlap_only_ram: region may only overlap RAM
> > > > > - * Return: status code
> > > > > - */
> > > > > -static efi_status_t efi_add_memory_map_pg(u64 start, u64 pages,
> > > > > - int memory_type,
> > > > > - bool overlap_only_ram)
> > > > > +static efi_status_t __efi_add_memory_map_pg(u64 start, u64 pages,
> > > > > + int memory_type,
> > > > > + bool overlap_only_ram)
> > > > > {
> > > > > struct list_head *lhandle;
> > > > > struct efi_mem_list *newlist;
> > > > > @@ -395,6 +418,29 @@ static efi_status_t efi_add_memory_map_pg(u64 start, u64 pages,
> > > > > }
> > > > > }
> > > > >
> > > > > + return EFI_SUCCESS;
> > > > > +}
> > > > > +
> > > > > +/**
> > > > > + * efi_add_memory_map_pg() - add pages to the memory map
> > > > > + *
> > > > > + * @start: start address, must be a multiple of EFI_PAGE_SIZE
> > > > > + * @pages: number of pages to add
> > > > > + * @memory_type: type of memory added
> > > > > + * @overlap_only_ram: region may only overlap RAM
> > > > > + * Return: status code
> > > > > + */
> > > > > +static efi_status_t efi_add_memory_map_pg(u64 start, u64 pages,
> > > > > + int memory_type,
> > > > > + bool overlap_only_ram)
> > > > > +{
> > > > > + efi_status_t status;
> > > > > +
> > > > > + status = __efi_add_memory_map_pg(start, pages, memory_type,
> > > > > + overlap_only_ram);
> > > > > + if (status != EFI_SUCCESS)
> > > > > + return status;
> > > > > +
> > > > > if (CONFIG_IS_ENABLED(MEM_MAP_UPDATE_NOTIFY))
> > > > > efi_map_update_notify(start, pages << EFI_PAGE_SHIFT,
> > > > > memory_type == EFI_CONVENTIONAL_MEMORY ?
> > > >
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