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| author | Ard Biesheuvel <ard.biesheuvel@linaro.org> | 2016-11-24 18:02:23 +0000 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2016-11-25 07:15:23 +0100 |
| commit | 018edcfac4c3b140366ad51b0907f3becb5bb624 (patch) | |
| tree | cbde451448c6a304321a969401f853ea2239333c /drivers/firmware | |
| parent | b2c74191f4672c4b3265d0335910792b4f72026b (diff) | |
| download | linux-018edcfac4c3b140366ad51b0907f3becb5bb624.tar.gz linux-018edcfac4c3b140366ad51b0907f3becb5bb624.tar.bz2 linux-018edcfac4c3b140366ad51b0907f3becb5bb624.zip | |
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.c | 13 |
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; } /* |