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authorArd Biesheuvel <ard.biesheuvel@linaro.org>2016-11-24 18:02:23 +0000
committerIngo Molnar <mingo@kernel.org>2016-11-25 07:15:23 +0100
commit018edcfac4c3b140366ad51b0907f3becb5bb624 (patch)
treecbde451448c6a304321a969401f853ea2239333c /drivers/firmware
parentb2c74191f4672c4b3265d0335910792b4f72026b (diff)
efi/libstub: Make efi_random_alloc() allocate below 4 GB on 32-bit
The UEFI stub executes in the context of the firmware, which identity maps the available system RAM, which implies that only memory below 4 GB can be used for allocations on 32-bit architectures, even on [L]PAE capable hardware. So ignore any reported memory above 4 GB in efi_random_alloc(). This also fixes a reported build problem on ARM under -Os, where the 64-bit logical shift relies on a software routine that the ARM decompressor does not provide. A second [minor] issue is also fixed, where the '+ 1' is moved out of the shift, where it belongs: the reason for its presence is that a memory region where start == end should count as a single slot, given that 'end' takes the desired size and alignment of the allocation into account. To clarify the code in this regard, rename start/end to 'first_slot' and 'last_slot', respectively, and introduce 'region_end' to describe the last usable address of the current region. Reported-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Matt Fleming <matt@codeblueprint.co.uk> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-efi@vger.kernel.org Link: http://lkml.kernel.org/r/1480010543-25709-2-git-send-email-ard.biesheuvel@linaro.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'drivers/firmware')
-rw-r--r--drivers/firmware/efi/libstub/random.c13
1 files changed, 7 insertions, 6 deletions
diff --git a/drivers/firmware/efi/libstub/random.c b/drivers/firmware/efi/libstub/random.c
index 3a3feacc329f..7e72954d5860 100644
--- a/drivers/firmware/efi/libstub/random.c
+++ b/drivers/firmware/efi/libstub/random.c
@@ -45,19 +45,20 @@ static unsigned long get_entry_num_slots(efi_memory_desc_t *md,
unsigned long align_shift)
{
unsigned long align = 1UL << align_shift;
- u64 start, end;
+ u64 first_slot, last_slot, region_end;
if (md->type != EFI_CONVENTIONAL_MEMORY)
return 0;
- start = round_up(md->phys_addr, align);
- end = round_down(md->phys_addr + md->num_pages * EFI_PAGE_SIZE - size,
- align);
+ region_end = min((u64)ULONG_MAX, md->phys_addr + md->num_pages*EFI_PAGE_SIZE - 1);
- if (start > end)
+ first_slot = round_up(md->phys_addr, align);
+ last_slot = round_down(region_end - size + 1, align);
+
+ if (first_slot > last_slot)
return 0;
- return (end - start + 1) >> align_shift;
+ return ((unsigned long)(last_slot - first_slot) >> align_shift) + 1;
}
/*