Commit-ID: 018edcfac4c3b140366ad51b0907f3becb5bb624 Gitweb: http://git.kernel.org/tip/018edcfac4c3b140366ad51b0907f3becb5bb624 Author: Ard Biesheuvel <ard.biesheu...@linaro.org> AuthorDate: Thu, 24 Nov 2016 18:02:23 +0000 Committer: Ingo Molnar <mi...@kernel.org> CommitDate: Fri, 25 Nov 2016 07:15:23 +0100
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 <a...@arndb.de> Signed-off-by: Ard Biesheuvel <ard.biesheu...@linaro.org> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Matt Fleming <m...@codeblueprint.co.uk> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Thomas Gleixner <t...@linutronix.de> Cc: linux-...@vger.kernel.org Link: http://lkml.kernel.org/r/1480010543-25709-2-git-send-email-ard.biesheu...@linaro.org Signed-off-by: Ingo Molnar <mi...@kernel.org> --- drivers/firmware/efi/libstub/random.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) diff --git a/drivers/firmware/efi/libstub/random.c b/drivers/firmware/efi/libstub/random.c index 3a3feac..7e72954 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; } /*
