efi/libstub: arm*: Pass latest memory map to the kernel

From: Ard Biesheuvel <[email protected]>

As reported by James, the current libstub code involving the annotated memory map only works somewhat correctly by accident, due to the fact that a pool allocation happens to be reused immediately, retaining its former contents.

Instead of juggling memory maps, which makes the code more complex than it needs to be, simply put a placholder value into the FDT, and only write the actual value after ExitBootServices() has been called.

Reported-by James Morse <[email protected]>

Signed-off-by Ard Biesheuvel <[email protected]>

[Update mmap-size too, remove updated_fdt()s unused params and header entry]

Signed-off-by James Morse <[email protected]>

---
Hi Ard,

This is a v2 of your patch that updates the mmap-size too. This solves the truncated memmap problem I saw with v1 on Seattle.

The original patch was CC-stable, so I think this should also have:

Cc <[email protected]>

Fixes ed9cc156c42f ("efi/libstub: Use efi_exit_boot_services() in FDT")

Thanks,

James

 drivers/firmware/efi/libstub/efistub.h |  8 ----
 drivers/firmware/efi/libstub/fdt.c     | 75 +++++++++++++++++++++-------------
 2 files changed, 47 insertions(+), 36 deletions(-)

Quoted 28 lines · James Morse

From: Ard Biesheuvel <[email protected]>

As reported by James, the current libstub code involving the annotated memory map only works somewhat correctly by accident, due to the fact that a pool allocation happens to be reused immediately, retaining its former contents.

Instead of juggling memory maps, which makes the code more complex than it needs to be, simply put a placholder value into the FDT, and only write the actual value after ExitBootServices() has been called.

Reported-by James Morse <[email protected]>

Signed-off-by Ard Biesheuvel <[email protected]>

[Update mmap-size too, remove updated_fdt()s unused params and header entry]

Signed-off-by James Morse <[email protected]>

---
Hi Ard,

This is a v2 of your patch that updates the mmap-size too. This solves the truncated memmap problem I saw with v1 on Seattle.

The original patch was CC-stable, so I think this should also have:

Cc <[email protected]>

Fixes ed9cc156c42f ("efi/libstub: Use efi_exit_boot_services() in FDT")

Thanks,

Quoted 5 lines

James

 drivers/firmware/efi/libstub/efistub.h |  8 ----
 drivers/firmware/efi/libstub/fdt.c     | 75 +++++++++++++++++++++-------------
 2 files changed, 47 insertions(+), 36 deletions(-)

Thanks James. I've queued this one up in the 'urgent' queue and tagged it for stable. I'll send it to tip before the end of the week.

Quoted 29 lines · Matt Fleming

Quoted 28 lines · James Morse

From: Ard Biesheuvel <[email protected]>

As reported by James, the current libstub code involving the annotated memory map only works somewhat correctly by accident, due to the fact that a pool allocation happens to be reused immediately, retaining its former contents.

Instead of juggling memory maps, which makes the code more complex than it needs to be, simply put a placholder value into the FDT, and only write the actual value after ExitBootServices() has been called.

Reported-by James Morse <[email protected]>

Signed-off-by Ard Biesheuvel <[email protected]>

[Update mmap-size too, remove updated_fdt()s unused params and header entry]

Signed-off-by James Morse <[email protected]>

---
Hi Ard,

This is a v2 of your patch that updates the mmap-size too. This solves the truncated memmap problem I saw with v1 on Seattle.

The original patch was CC-stable, so I think this should also have:

Cc <[email protected]>

Fixes ed9cc156c42f ("efi/libstub: Use efi_exit_boot_services() in FDT")

Thanks,

Quoted 8 lines

Quoted 5 lines

James

 drivers/firmware/efi/libstub/efistub.h |  8 ----
 drivers/firmware/efi/libstub/fdt.c     | 75 +++++++++++++++++++++-------------
 2 files changed, 47 insertions(+), 36 deletions(-)

Thanks James. I've queued this one up in the 'urgent' queue and tagged it for stable. I'll send it to tip before the end of the week.

Could we fold the hunk below, please?

drivers/firmware/efi/libstub/fdt.c +5 -6

index 9b11b0559a23..90ab96845937 100644
@@ -149,26 +149,25 @@ static efi_status_t
 update_fdt(efi_system_table_t *sys_table, void *orig_fdt,
 static efi_status_t update_fdt_memmap(void *fdt, u64 memmap, u32 map_size)
 {
        int node = fdt_path_offset(fdt, "/chosen");
-       efi_status_t status;
+       int err;
 
        if (node < 0)
                return EFI_LOAD_ERROR;
 
        memmap = cpu_to_fdt64(memmap);
-       status = fdt_setprop_inplace(fdt, node, "linux,uefi-mmap-start",
-                                    &memmap, sizeof(memmap));
+       err = fdt_setprop_inplace(fdt, node, "linux,uefi-mmap-start",
+                                 &memmap, sizeof(memmap));
 
        if (status)
                return EFI_LOAD_ERROR;
 
        map_size = cpu_to_fdt32(map_size);
-       status = fdt_setprop_inplace(fdt, node, "linux,uefi-mmap-size",
-                                    &map_size, sizeof(map_size));
+       err = fdt_setprop_inplace(fdt, node, "linux,uefi-mmap-size",
+                                 &map_size, sizeof(map_size));
 
        if (status)
                return EFI_LOAD_ERROR;
 
-
        return EFI_SUCCESS;
 }

My mistake, and harmless in practice, but sloppy nonetheless