From: catalin.marinas@arm.com (Catalin Marinas)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 14/14] ARM: elf: add new hwcap for identifying atomic ldrd/strd instructions
Date: Mon, 20 May 2013 15:18:09 +0100 [thread overview]
Message-ID: <20130520141809.GA27473@arm.com> (raw)
In-Reply-To: <1368810473-26070-15-git-send-email-will.deacon@arm.com>
On Fri, May 17, 2013 at 06:07:53PM +0100, Will Deacon wrote:
> CPUs implementing LPAE have atomic ldrd/strd instructions, meaning that
> userspace software can avoid having to use the exclusive variants of
> these instructions if they wish.
>
> This patch advertises the atomicity of these instructions via the
> hwcaps, so userspace can detect this CPU feature.
>
> Reported-by: Vladimir Danushevsky <vladimir.danushevsky@oracle.com>
> Signed-off-by: Will Deacon <will.deacon@arm.com>
...
> +
> + /* LPAE implies atomic ldrd/strd instructions */
> + vmsa = (read_cpuid_ext(CPUID_EXT_MMFR0) & 0xf) >> 0;
> + if (vmsa >= 5)
> + elf_hwcap |= HWCAP_LPAE;
As I mentioned in the past, I don't agree with exposing the "LPAE"
feature to user-space, it's not a feature that user space should care
about. An atomic double hwcap is better and you can even make this per
CPU via __v7_proc.
--
Catalin
next prev parent reply other threads:[~2013-05-20 14:18 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-05-17 17:07 [PATCH 00/14] Random LPAE-related patches Will Deacon
2013-05-17 17:07 ` [PATCH 01/14] ARM: LPAE: use signed arithmetic for mask definitions Will Deacon
2013-05-17 17:07 ` [PATCH 02/14] ARM: LPAE: use phys_addr_t in alloc_init_pud() Will Deacon
2013-05-17 17:07 ` [PATCH 03/14] ARM: LPAE: use phys_addr_t in free_memmap() Will Deacon
2013-05-17 17:07 ` [PATCH 04/14] ARM: LPAE: use phys_addr_t for initrd location Will Deacon
2013-05-17 17:07 ` [PATCH 05/14] ARM: LPAE: use phys_addr_t in switch_mm() Will Deacon
2013-05-17 17:07 ` [PATCH 06/14] ARM: LPAE: use 64-bit accessors for TTBR registers Will Deacon
2013-05-17 17:07 ` [PATCH 07/14] ARM: LPAE: factor out T1SZ and TTBR1 computations Will Deacon
2013-05-17 17:07 ` [PATCH 08/14] ARM: LPAE: accomodate >32-bit addresses for page table base Will Deacon
2013-05-17 17:07 ` [PATCH 09/14] ARM: mm: use physical addresses in highmem sanity checks Will Deacon
2013-05-17 17:07 ` [PATCH 10/14] ARM: fix type of PHYS_PFN_OFFSET to unsigned long Will Deacon
2013-05-17 17:07 ` [PATCH 11/14] ARM: mm: cleanup checks for membank overlap with vmalloc area Will Deacon
2013-05-17 17:07 ` [PATCH 12/14] ARM: mm: clean up membank size limit checks Will Deacon
2013-05-17 17:07 ` [PATCH 13/14] ARM: lpae: fix definition of PTE_HWTABLE_PTRS Will Deacon
2013-05-17 17:07 ` [PATCH 14/14] ARM: elf: add new hwcap for identifying atomic ldrd/strd instructions Will Deacon
2013-05-20 14:18 ` Catalin Marinas [this message]
2013-05-20 14:24 ` Will Deacon
2013-05-20 15:11 ` Catalin Marinas
2013-05-20 16:04 ` Will Deacon
2013-05-20 17:13 ` Catalin Marinas
2013-05-21 18:02 ` Will Deacon
2013-05-22 8:43 ` Catalin Marinas
2013-05-21 18:48 ` Rob Herring
2013-05-22 8:47 ` Catalin Marinas
2013-05-22 18:09 ` Will Deacon
2013-05-23 8:50 ` Catalin Marinas
2013-05-17 18:23 ` [PATCH 00/14] Random LPAE-related patches Santosh Shilimkar
2013-05-30 13:31 ` Subash Patel
2013-05-30 15:03 ` Will Deacon
2013-05-31 0:38 ` Kukjin Kim
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