1. 28 1月, 2017 24 次提交
    • I
      x86/boot/e820: Rename early_reserve_e820() to e820__memblock_alloc() and document it · 5da217ca
      Ingo Molnar 提交于
      early_reserve_e820() is an early hack for kexec that does a limited fixup of the
      mptable and passes it to the kexec kernel as if it was the real thing.
      
      For this it needs to allocate memory - but no memory allocator is available yet
      beyond the memblock allocator, so early_reserve_e820() is really a wrapper
      around memblock_alloc() plus a hack to update the e820_table_firmware entries.
      
      The name 'reserve' is really a bit of a misnomer, as 'reserved' memory typically
      means memory completely inaccessible to the kernel - while here what we want to do
      is a special RAM allocation for our own purposes and insert that as RAM_RESERVED.
      
      Rename the function to e820__memblock_alloc_reserved() to better signal this dual
      purpose, plus document it better, which was omitted when it was merged. The barely
      comprehensible and cryptic comment:
      
        /*
         * pre allocated 4k and reserved it in memblock and e820_table_firmware
         */
        u64 __init e820__memblock_alloc_reserved(u64 size, u64 align)
      
      ... does not count as documentation, replace it with:
      
        /*
         * Allocate the requested number of bytes with the requsted alignment
         * and return (the physical address) to the caller. Also register this
         * range in the 'firmware' E820 table.
         *
         * This allows kexec to fake a new mptable, as if it came from the real
         * system.
         */
        u64 __init e820__memblock_alloc_reserved(u64 size, u64 align)
      
      No change in functionality.
      
      Cc: Alex Thorlton <athorlton@sgi.com>
      Cc: Andy Lutomirski <luto@kernel.org>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Dan Williams <dan.j.williams@intel.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Huang, Ying <ying.huang@intel.com>
      Cc: Josh Poimboeuf <jpoimboe@redhat.com>
      Cc: Juergen Gross <jgross@suse.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Paul Jackson <pj@sgi.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Rafael J. Wysocki <rjw@sisk.pl>
      Cc: Tejun Heo <tj@kernel.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Wei Yang <richard.weiyang@gmail.com>
      Cc: Yinghai Lu <yinghai@kernel.org>
      Cc: linux-kernel@vger.kernel.org
      Signed-off-by: NIngo Molnar <mingo@kernel.org>
      5da217ca
    • I
      x86/boot/e820: Clarify the role of finish_e820_parsing() and rename it to... · 9641bdaf
      Ingo Molnar 提交于
      x86/boot/e820: Clarify the role of finish_e820_parsing() and rename it to e820__finish_early_params()
      
      finish_e820_parsing() is closely related to parse_early_params(), but the
      name does not tell us this clearly, so rename it to e820__finish_early_params().
      
      Also add a few comments to explain what the function does.
      
      No change in functionality.
      
      Cc: Alex Thorlton <athorlton@sgi.com>
      Cc: Andy Lutomirski <luto@kernel.org>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Dan Williams <dan.j.williams@intel.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Huang, Ying <ying.huang@intel.com>
      Cc: Josh Poimboeuf <jpoimboe@redhat.com>
      Cc: Juergen Gross <jgross@suse.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Paul Jackson <pj@sgi.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Rafael J. Wysocki <rjw@sisk.pl>
      Cc: Tejun Heo <tj@kernel.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Wei Yang <richard.weiyang@gmail.com>
      Cc: Yinghai Lu <yinghai@kernel.org>
      Cc: linux-kernel@vger.kernel.org
      Signed-off-by: NIngo Molnar <mingo@kernel.org>
      9641bdaf
    • I
      x86/boot/e820: Move e820_reserve_setup_data() to e820.c · da92139b
      Ingo Molnar 提交于
      The e820_reserve_setup_data() is local to arch/x86/kernel/setup.c,
      but it is E820 functionality - so move it to e820.c to better
      isolate E820 functionality.
      
      No change in functionality.
      
      Cc: Alex Thorlton <athorlton@sgi.com>
      Cc: Andy Lutomirski <luto@kernel.org>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Dan Williams <dan.j.williams@intel.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Huang, Ying <ying.huang@intel.com>
      Cc: Josh Poimboeuf <jpoimboe@redhat.com>
      Cc: Juergen Gross <jgross@suse.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Paul Jackson <pj@sgi.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Rafael J. Wysocki <rjw@sisk.pl>
      Cc: Tejun Heo <tj@kernel.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Wei Yang <richard.weiyang@gmail.com>
      Cc: Yinghai Lu <yinghai@kernel.org>
      Cc: linux-kernel@vger.kernel.org
      Signed-off-by: NIngo Molnar <mingo@kernel.org>
      da92139b
    • I
      x86/boot/e820: Rename parse_e820_ext() to e820__memory_setup_extended() · 914053c0
      Ingo Molnar 提交于
      parse_e820_ext() is very similar to e820__memory_setup_default(), both are
      taking bootloader provided data, add it to the E820 table and then
      pass it sanitize_e820_table().
      
      Rename it to e820__memory_setup_extended() to better signal their similar role.
      
      No change in functionality.
      
      Cc: Alex Thorlton <athorlton@sgi.com>
      Cc: Andy Lutomirski <luto@kernel.org>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Dan Williams <dan.j.williams@intel.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Huang, Ying <ying.huang@intel.com>
      Cc: Josh Poimboeuf <jpoimboe@redhat.com>
      Cc: Juergen Gross <jgross@suse.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Paul Jackson <pj@sgi.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Rafael J. Wysocki <rjw@sisk.pl>
      Cc: Tejun Heo <tj@kernel.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Wei Yang <richard.weiyang@gmail.com>
      Cc: Yinghai Lu <yinghai@kernel.org>
      Cc: linux-kernel@vger.kernel.org
      Signed-off-by: NIngo Molnar <mingo@kernel.org>
      914053c0
    • I
      x86/boot/e820: Move the memblock_find_dma_reserve() function and rename it to... · 4270fd8b
      Ingo Molnar 提交于
      x86/boot/e820: Move the memblock_find_dma_reserve() function and rename it to memblock_set_dma_reserve()
      
      We introduced memblock_find_dma_reserve() in this commit:
      
         6f2a7536 x86, memblock: Use memblock_memory_size()/memblock_free_memory_size() to get correct dma_reserve
      
      But there's several problems with it:
      
       - The changelog is full of typos and is incomprehensible in general, and
         the comments in the code are not much better either.
      
       - The function was inexplicably placed into e820.c, while it has very
         little connection to the E820 table: when we call
         memblock_find_dma_reserve() then memblock is already set up and we
         are not using the E820 table anymore.
      
       - The function is a wrapper around set_dma_reserve(), but changed the 'set'
         name to 'find' - actively misleading about its primary purpose, which is
         still to set the DMA-reserve value.
      
       - The function is limited to 64-bit systems, but neither the changelog nor
         the comments explain why. The change would appear to be relevant to
         32-bit systems as well, as the ISA DMA zone is the first 16 MB of RAM.
      
      So address some of these problems:
      
       - Move it into arch/x86/mm/init.c, next to the other zone setup related
         functions.
      
       - Clean up the code flow and names of local variables a bit.
      
       - Rename it to memblock_set_dma_reserve()
      
       - Improve the comments.
      
      No change in functionality. Enabling it for 32-bit systems is left
      for a separate patch.
      
      Cc: Alex Thorlton <athorlton@sgi.com>
      Cc: Andy Lutomirski <luto@kernel.org>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Dan Williams <dan.j.williams@intel.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Huang, Ying <ying.huang@intel.com>
      Cc: Josh Poimboeuf <jpoimboe@redhat.com>
      Cc: Juergen Gross <jgross@suse.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Paul Jackson <pj@sgi.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Rafael J. Wysocki <rjw@sisk.pl>
      Cc: Tejun Heo <tj@kernel.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Wei Yang <richard.weiyang@gmail.com>
      Cc: Yinghai Lu <yinghai@kernel.org>
      Cc: linux-kernel@vger.kernel.org
      Signed-off-by: NIngo Molnar <mingo@kernel.org>
      4270fd8b
    • I
      x86/boot/e820: Rename memblock_x86_fill() to e820__memblock_setup() and improve the explanations · 4918e228
      Ingo Molnar 提交于
      So memblock_x86_fill() is another E820 code misnomer:
      
       - nothing in its name tells us that it's part of the E820 subsystem ...
      
       - The 'fill' wording is ambiguous and doesn't tell us whether it's a single
         entry or some process - while the _real_ purpose of the function is hidden,
         which is to do a complete setup of the (platform independent) memblock regions.
      
      So rename it accordingly, to e820__memblock_setup().
      
      Also translate this incomprehensible and misleading comment:
      
              /*
      	 * EFI may have more than 128 entries
      	 * We are safe to enable resizing, beause memblock_x86_fill()
      	 * is rather later for x86
      	 */
              memblock_allow_resize();
      
      The worst aspect of this comment isn't even the sloppy typos, but that it
      casually mentions a '128' number with no explanation, which makes one lead
      to the assumption that this is related to the well-known limit of a maximum
      of 128 E820 entries passed via legacy bootloaders.
      
      But no, the _real_ meaning of 128 here is that of the memblock subsystem,
      which too happens to have a 128 entries limit for very early memblock
      regions (which is unrelated to E820), via INIT_MEMBLOCK_REGIONS ...
      
      So change the comment to a more comprehensible version:
      
              /*
               * The bootstrap memblock region count maximum is 128 entries
               * (INIT_MEMBLOCK_REGIONS), but EFI might pass us more E820 entries
               * than that - so allow memblock resizing.
               *
               * This is safe, because this call happens pretty late during x86 setup,
               * so we know about reserved memory regions already. (This is important
               * so that memblock resizing does no stomp over reserved areas.)
               */
              memblock_allow_resize();
      
      No change in functionality.
      
      Cc: Alex Thorlton <athorlton@sgi.com>
      Cc: Andy Lutomirski <luto@kernel.org>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Dan Williams <dan.j.williams@intel.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Huang, Ying <ying.huang@intel.com>
      Cc: Josh Poimboeuf <jpoimboe@redhat.com>
      Cc: Juergen Gross <jgross@suse.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Paul Jackson <pj@sgi.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Rafael J. Wysocki <rjw@sisk.pl>
      Cc: Tejun Heo <tj@kernel.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Wei Yang <richard.weiyang@gmail.com>
      Cc: Yinghai Lu <yinghai@kernel.org>
      Cc: linux-kernel@vger.kernel.org
      Signed-off-by: NIngo Molnar <mingo@kernel.org>
      4918e228
    • I
      x86/boot/e820: Rename e820_table_saved to e820_table_firmware and improve the description · 544a0f47
      Ingo Molnar 提交于
      So the 'e820_table_saved' is a bit of a misnomer that hides its real purpose.
      
      At first sight the name suggests that it's some sort save/restore mechanism,
      as this is how we typically name such facilities in the kernel.
      
      But that is not so, e820_table_saved is the original firmware version of the
      e820 table, not modified by the kernel. This table is displayed in the
      /sys/firmware/memmap file, and it's also used by the hibernation code to
      calculate a physical memory layout MD5 fingerprint checksum which is
      invariant of the kernel.
      
      So rename it to 'e820_table_firmware' and update all the comments to better
      describe the main e820 data strutures.
      
      Also rename:
      
        'initial_e820_table_saved'  =>  'e820_table_firmware_init'
        'e820_update_range_saved'   =>  'e820_update_range_firmware'
      
      ... to better match the new nomenclature.
      
      No change in functionality.
      
      Cc: Alex Thorlton <athorlton@sgi.com>
      Cc: Andy Lutomirski <luto@kernel.org>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Dan Williams <dan.j.williams@intel.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Huang, Ying <ying.huang@intel.com>
      Cc: Josh Poimboeuf <jpoimboe@redhat.com>
      Cc: Juergen Gross <jgross@suse.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Paul Jackson <pj@sgi.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Rafael J. Wysocki <rjw@sisk.pl>
      Cc: Tejun Heo <tj@kernel.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Wei Yang <richard.weiyang@gmail.com>
      Cc: Yinghai Lu <yinghai@kernel.org>
      Cc: linux-kernel@vger.kernel.org
      Signed-off-by: NIngo Molnar <mingo@kernel.org>
      544a0f47
    • I
      x86/boot/e820: Rename default_machine_specific_memory_setup() to e820__memory_setup_default() · 103e2063
      Ingo Molnar 提交于
      The default_machine_specific_memory_setup() is a mouthful and despite the
      many words it doesn't actually tell us clearly what it does.
      
      The function is the x86 legacy memory layout setup code, based on
      E820-formatted memory layout information passed by the bootloader
      via the boot_params.
      
      Rename it to e820__memory_setup_default() to better signal its purpose.
      
      Also rename the related higher level function to be consistent with
      this new naming:
      
          setup_memory_map() => e820__memory_setup()
      
      No change in functionality.
      
      Cc: Alex Thorlton <athorlton@sgi.com>
      Cc: Andy Lutomirski <luto@kernel.org>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Dan Williams <dan.j.williams@intel.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Huang, Ying <ying.huang@intel.com>
      Cc: Josh Poimboeuf <jpoimboe@redhat.com>
      Cc: Juergen Gross <jgross@suse.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Paul Jackson <pj@sgi.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Rafael J. Wysocki <rjw@sisk.pl>
      Cc: Tejun Heo <tj@kernel.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Wei Yang <richard.weiyang@gmail.com>
      Cc: Yinghai Lu <yinghai@kernel.org>
      Cc: linux-kernel@vger.kernel.org
      Signed-off-by: NIngo Molnar <mingo@kernel.org>
      103e2063
    • I
      x86/boot/e820: Harmonize the 'struct e820_table' fields · bf495573
      Ingo Molnar 提交于
      So the e820_table->map and e820_table->nr_map names are a bit
      confusing, because it's not clear what a 'map' really means
      (it could be a bitmap, or some other data structure), nor is
      it clear what nr_map means (is it a current index, or some
      other count).
      
      Rename the fields from:
      
       e820_table->map        =>     e820_table->entries
       e820_table->nr_map     =>     e820_table->nr_entries
      
      which makes it abundantly clear that these are entries
      of the table, and that the size of the table is ->nr_entries.
      
      Propagate the changes to all affected files. Where necessary,
      adjust local variable names to better reflect the new field names.
      
      No change in functionality.
      
      Cc: Alex Thorlton <athorlton@sgi.com>
      Cc: Andy Lutomirski <luto@kernel.org>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Dan Williams <dan.j.williams@intel.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Huang, Ying <ying.huang@intel.com>
      Cc: Josh Poimboeuf <jpoimboe@redhat.com>
      Cc: Juergen Gross <jgross@suse.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Paul Jackson <pj@sgi.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Rafael J. Wysocki <rjw@sisk.pl>
      Cc: Tejun Heo <tj@kernel.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Wei Yang <richard.weiyang@gmail.com>
      Cc: Yinghai Lu <yinghai@kernel.org>
      Cc: linux-kernel@vger.kernel.org
      Signed-off-by: NIngo Molnar <mingo@kernel.org>
      bf495573
    • I
      x86/boot/e820: Rename everything to e820_table · 61a50101
      Ingo Molnar 提交于
      No change in functionality.
      
      Cc: Alex Thorlton <athorlton@sgi.com>
      Cc: Andy Lutomirski <luto@kernel.org>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Dan Williams <dan.j.williams@intel.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Huang, Ying <ying.huang@intel.com>
      Cc: Josh Poimboeuf <jpoimboe@redhat.com>
      Cc: Juergen Gross <jgross@suse.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Paul Jackson <pj@sgi.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Rafael J. Wysocki <rjw@sisk.pl>
      Cc: Tejun Heo <tj@kernel.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Wei Yang <richard.weiyang@gmail.com>
      Cc: Yinghai Lu <yinghai@kernel.org>
      Cc: linux-kernel@vger.kernel.org
      Signed-off-by: NIngo Molnar <mingo@kernel.org>
      61a50101
    • I
      x86/boot/e820: Rename 'e820_map' variables to 'e820_array' · acd4c048
      Ingo Molnar 提交于
      In line with the rename to 'struct e820_array', harmonize the naming of common e820
      table variable names as well:
      
       e820          =>  e820_array
       e820_saved    =>  e820_array_saved
       e820_map      =>  e820_array
       initial_e820  =>  e820_array_init
      
      This makes the variable names more consistent  and easier to grep for.
      
      No change in functionality.
      
      Cc: Alex Thorlton <athorlton@sgi.com>
      Cc: Andy Lutomirski <luto@kernel.org>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Dan Williams <dan.j.williams@intel.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Huang, Ying <ying.huang@intel.com>
      Cc: Josh Poimboeuf <jpoimboe@redhat.com>
      Cc: Juergen Gross <jgross@suse.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Paul Jackson <pj@sgi.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Rafael J. Wysocki <rjw@sisk.pl>
      Cc: Tejun Heo <tj@kernel.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Wei Yang <richard.weiyang@gmail.com>
      Cc: Yinghai Lu <yinghai@kernel.org>
      Cc: linux-kernel@vger.kernel.org
      Signed-off-by: NIngo Molnar <mingo@kernel.org>
      acd4c048
    • I
      x86/boot/e820: Remove e820_mark_nosave_regions() definition uglies · e79d74d0
      Ingo Molnar 提交于
      The e820_mark_nosave_regions definition has a number of ugly #ifdef
      conditions that unnecessarily uglify both the header and the
      e820.c file.
      
      Make this function unconditional: most distro kernels have hibernation
      enabled. If LTO functionality is added in the future it will be able
      to eliminate unused functions without uglifying the source code.
      
      No change in functionality.
      
      Cc: Alex Thorlton <athorlton@sgi.com>
      Cc: Andy Lutomirski <luto@kernel.org>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Dan Williams <dan.j.williams@intel.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Huang, Ying <ying.huang@intel.com>
      Cc: Josh Poimboeuf <jpoimboe@redhat.com>
      Cc: Juergen Gross <jgross@suse.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Paul Jackson <pj@sgi.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Rafael J. Wysocki <rjw@sisk.pl>
      Cc: Tejun Heo <tj@kernel.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Wei Yang <richard.weiyang@gmail.com>
      Cc: Yinghai Lu <yinghai@kernel.org>
      Cc: linux-kernel@vger.kernel.org
      Signed-off-by: NIngo Molnar <mingo@kernel.org>
      e79d74d0
    • I
      x86/boot/e820: Remove unnecessary #include <linux/ioport.h> from asm/e820/api.h · 9de94dbb
      Ingo Molnar 提交于
      There's a completely unnecessary inclusion of linux/ioport.h near
      the end of the asm/e820/api.h file.
      
      Remove it and fix up unrelated code that learned to rely on this
      spurious inclusion of a generic header.
      
      No change in functionality.
      
      Cc: Alex Thorlton <athorlton@sgi.com>
      Cc: Andy Lutomirski <luto@kernel.org>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Dan Williams <dan.j.williams@intel.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Huang, Ying <ying.huang@intel.com>
      Cc: Josh Poimboeuf <jpoimboe@redhat.com>
      Cc: Juergen Gross <jgross@suse.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Paul Jackson <pj@sgi.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Rafael J. Wysocki <rjw@sisk.pl>
      Cc: Tejun Heo <tj@kernel.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Wei Yang <richard.weiyang@gmail.com>
      Cc: Yinghai Lu <yinghai@kernel.org>
      Cc: linux-kernel@vger.kernel.org
      Signed-off-by: NIngo Molnar <mingo@kernel.org>
      9de94dbb
    • I
      x86/boot/e820: Rename the basic e820 data types to 'struct e820_entry' and 'struct e820_array' · 8ec67d97
      Ingo Molnar 提交于
      The 'e820entry' and 'e820map' names have various annoyances:
      
       - the missing underscore departs from the usual kernel style
         and makes the code look weird,
      
       - in the past I kept confusing the 'map' with the 'entry', because
         a 'map' is ambiguous in that regard,
      
       - it's not really clear from the 'e820map' that this is a regular
         C array.
      
      Rename them to 'struct e820_entry' and 'struct e820_array' accordingly.
      
      ( Leave the legacy UAPI header alone but do the rename in the bootparam.h
        and e820/types.h file - outside tools relying on these defines should
        either adjust their code, or should use the legacy header, or should
        create their private copies for the definitions. )
      
      No change in functionality.
      
      Cc: Alex Thorlton <athorlton@sgi.com>
      Cc: Andy Lutomirski <luto@kernel.org>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Dan Williams <dan.j.williams@intel.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Huang, Ying <ying.huang@intel.com>
      Cc: Josh Poimboeuf <jpoimboe@redhat.com>
      Cc: Juergen Gross <jgross@suse.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Paul Jackson <pj@sgi.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Rafael J. Wysocki <rjw@sisk.pl>
      Cc: Tejun Heo <tj@kernel.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Wei Yang <richard.weiyang@gmail.com>
      Cc: Yinghai Lu <yinghai@kernel.org>
      Cc: linux-kernel@vger.kernel.org
      Signed-off-by: NIngo Molnar <mingo@kernel.org>
      8ec67d97
    • I
      x86/boot/e820: Move HIGH_MEMORY define to asm/e820/types.h · 308bee69
      Ingo Molnar 提交于
      The HIGH_MEMORY define was in the API header, while it conceptually
      belongs to the other physical memory ranges in the e820/types.h
      header.
      
      Move it there - and also convert the 1MB address to hexa, so that
      it lines up more nicely with the other memory address values.
      
      No change in functionality.
      
      Cc: Alex Thorlton <athorlton@sgi.com>
      Cc: Andy Lutomirski <luto@kernel.org>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Dan Williams <dan.j.williams@intel.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Huang, Ying <ying.huang@intel.com>
      Cc: Josh Poimboeuf <jpoimboe@redhat.com>
      Cc: Juergen Gross <jgross@suse.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Paul Jackson <pj@sgi.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Rafael J. Wysocki <rjw@sisk.pl>
      Cc: Tejun Heo <tj@kernel.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Wei Yang <richard.weiyang@gmail.com>
      Cc: Yinghai Lu <yinghai@kernel.org>
      Cc: linux-kernel@vger.kernel.org
      Signed-off-by: NIngo Molnar <mingo@kernel.org>
      308bee69
    • I
      x86/boot/e820: Remove unnecessary __ASSEMBLY__ guard · 993f4b77
      Ingo Molnar 提交于
      asm/e820/api.h had a spurious __ASSEMBLY__ guard - but the
      API header is not included in any assembly files. Remove it.
      
      No change in functionality.
      
      Cc: Alex Thorlton <athorlton@sgi.com>
      Cc: Andy Lutomirski <luto@kernel.org>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Dan Williams <dan.j.williams@intel.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Huang, Ying <ying.huang@intel.com>
      Cc: Josh Poimboeuf <jpoimboe@redhat.com>
      Cc: Juergen Gross <jgross@suse.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Paul Jackson <pj@sgi.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Rafael J. Wysocki <rjw@sisk.pl>
      Cc: Tejun Heo <tj@kernel.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Wei Yang <richard.weiyang@gmail.com>
      Cc: Yinghai Lu <yinghai@kernel.org>
      Cc: linux-kernel@vger.kernel.org
      Signed-off-by: NIngo Molnar <mingo@kernel.org>
      993f4b77
    • I
      x86/boot/e820: Clean up asm/e820/api.h · 0f856508
      Ingo Molnar 提交于
      Do a number of easy cleanups:
      
       - remove spurious linebreaks
      
       - remove spurious whitespace differences and inconsistent tabulation
      
       - remove unused and ugly 'struct setup_data;' pre-declaration
      
       - make all exported functionality 'extern' consistently
      
       - deobfuscate the (s,e) parameters of is_ISA_range(): (start, end)
      
      No change in functionality.
      
      Cc: Alex Thorlton <athorlton@sgi.com>
      Cc: Andy Lutomirski <luto@kernel.org>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Dan Williams <dan.j.williams@intel.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Huang, Ying <ying.huang@intel.com>
      Cc: Josh Poimboeuf <jpoimboe@redhat.com>
      Cc: Juergen Gross <jgross@suse.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Paul Jackson <pj@sgi.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Rafael J. Wysocki <rjw@sisk.pl>
      Cc: Tejun Heo <tj@kernel.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Wei Yang <richard.weiyang@gmail.com>
      Cc: Yinghai Lu <yinghai@kernel.org>
      Cc: linux-kernel@vger.kernel.org
      Signed-off-by: NIngo Molnar <mingo@kernel.org>
      0f856508
    • I
      x86/boot/e820: Remove assembly guard from asm/e820/types.h · b0bd00d6
      Ingo Molnar 提交于
      There's an assembly guard in asm/e820/types.h, and only
      a single .S file includes this header: arch/x86/boot/header.S,
      but it does not actually make use of any of the E820 defines.
      
      Remove the inclusion and remove the assembly guard as well.
      
      No change in functionality.
      
      Cc: Alex Thorlton <athorlton@sgi.com>
      Cc: Andy Lutomirski <luto@kernel.org>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Dan Williams <dan.j.williams@intel.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Huang, Ying <ying.huang@intel.com>
      Cc: Josh Poimboeuf <jpoimboe@redhat.com>
      Cc: Juergen Gross <jgross@suse.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Paul Jackson <pj@sgi.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Rafael J. Wysocki <rjw@sisk.pl>
      Cc: Tejun Heo <tj@kernel.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Wei Yang <richard.weiyang@gmail.com>
      Cc: Yinghai Lu <yinghai@kernel.org>
      Cc: linux-kernel@vger.kernel.org
      Signed-off-by: NIngo Molnar <mingo@kernel.org>
      b0bd00d6
    • I
      x86/boot/e820: Remove spurious asm/e820/api.h inclusions · 5520b7e7
      Ingo Molnar 提交于
      A commonly used lowlevel x86 header, asm/pgtable.h, includes asm/e820/api.h
      spuriously, without making direct use of it.
      
      Removing it is not simple: over the years various .c code learned to rely
      on this indirect inclusion.
      
      Remove the unnecessary include - this should speed up the kernel build a bit,
      as a large header is not included anymore in totally unrelated code.
      
      Cc: Alex Thorlton <athorlton@sgi.com>
      Cc: Andy Lutomirski <luto@kernel.org>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Dan Williams <dan.j.williams@intel.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Huang, Ying <ying.huang@intel.com>
      Cc: Josh Poimboeuf <jpoimboe@redhat.com>
      Cc: Juergen Gross <jgross@suse.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Paul Jackson <pj@sgi.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Rafael J. Wysocki <rjw@sisk.pl>
      Cc: Tejun Heo <tj@kernel.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Wei Yang <richard.weiyang@gmail.com>
      Cc: Yinghai Lu <yinghai@kernel.org>
      Cc: linux-kernel@vger.kernel.org
      Signed-off-by: NIngo Molnar <mingo@kernel.org>
      5520b7e7
    • I
      x86/boot/e820: Clean up the E820_X_MAX definition · 7b6e4ba3
      Ingo Molnar 提交于
      E820_X_MAX is defined in a somewhat messy fashion:
      
       - there's a pretty pointless looking #ifndef __KERNEL__ define that
         makes no sense in the non-UAPI header anymore,
      
       - part of it is defined in api.h, which is not for type definitions,
      
       - plus it's defined in two headers and the main explanation is in the
         header where we don't have the real definition.
      
      So move it into a single place in e820/types.h and get rid of the
      !__KERNEL__ case altogether. Drop the smaller comment - the larger
      one explains it just fine.
      
      Note that the zeropage does not use E820_X_MAX, it uses the legacy
      128 entries definition.
      
      No change in functionality.
      
      Cc: Alex Thorlton <athorlton@sgi.com>
      Cc: Andy Lutomirski <luto@kernel.org>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Dan Williams <dan.j.williams@intel.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Huang, Ying <ying.huang@intel.com>
      Cc: Josh Poimboeuf <jpoimboe@redhat.com>
      Cc: Juergen Gross <jgross@suse.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Paul Jackson <pj@sgi.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Rafael J. Wysocki <rjw@sisk.pl>
      Cc: Tejun Heo <tj@kernel.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Wei Yang <richard.weiyang@gmail.com>
      Cc: Yinghai Lu <yinghai@kernel.org>
      Cc: linux-kernel@vger.kernel.org
      Signed-off-by: NIngo Molnar <mingo@kernel.org>
      7b6e4ba3
    • I
      x86/boot/e820: Split minimal UAPI types out into uapi/asm/e820/types.h · 99da1ffe
      Ingo Molnar 提交于
      bootparam.h, which defines the legacy 'zeropage' boot parameter area,
      requires a small amount of e280 defines in the UAPI space - provide them.
      
      No change in functionality.
      
      Cc: Alex Thorlton <athorlton@sgi.com>
      Cc: Andy Lutomirski <luto@kernel.org>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Dan Williams <dan.j.williams@intel.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Huang, Ying <ying.huang@intel.com>
      Cc: Josh Poimboeuf <jpoimboe@redhat.com>
      Cc: Juergen Gross <jgross@suse.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Paul Jackson <pj@sgi.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Rafael J. Wysocki <rjw@sisk.pl>
      Cc: Tejun Heo <tj@kernel.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Wei Yang <richard.weiyang@gmail.com>
      Cc: Yinghai Lu <yinghai@kernel.org>
      Cc: linux-kernel@vger.kernel.org
      Signed-off-by: NIngo Molnar <mingo@kernel.org>
      99da1ffe
    • I
      x86/boot/e820: Move asm/e820.h to asm/e820/api.h · 66441bd3
      Ingo Molnar 提交于
      In line with asm/e820/types.h, move the e820 API declarations to
      asm/e820/api.h and update all usage sites.
      
      This is just a mechanical, obviously correct move & replace patch,
      there will be subsequent changes to clean up the code and to make
      better use of the new header organization.
      
      Cc: Alex Thorlton <athorlton@sgi.com>
      Cc: Andy Lutomirski <luto@kernel.org>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Dan Williams <dan.j.williams@intel.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Huang, Ying <ying.huang@intel.com>
      Cc: Josh Poimboeuf <jpoimboe@redhat.com>
      Cc: Juergen Gross <jgross@suse.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Paul Jackson <pj@sgi.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Rafael J. Wysocki <rjw@sisk.pl>
      Cc: Tejun Heo <tj@kernel.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Wei Yang <richard.weiyang@gmail.com>
      Cc: Yinghai Lu <yinghai@kernel.org>
      Cc: linux-kernel@vger.kernel.org
      Signed-off-by: NIngo Molnar <mingo@kernel.org>
      66441bd3
    • I
      x86/boot/e820: Clean up and improve comments in asm/e820/types.h · 7b80ba55
      Ingo Molnar 提交于
      Do some common-sense cleanups:
      
       - standardize on the kernel coding style consistently
      
       - tabulate definitions consistently
      
       - extend and clarify various descriptions
      
       - fix speling
      
       - update the header guard name according to the new position
      
       - etc.
      
      No change in functionality.
      
      Cc: Alex Thorlton <athorlton@sgi.com>
      Cc: Andy Lutomirski <luto@kernel.org>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Dan Williams <dan.j.williams@intel.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Huang, Ying <ying.huang@intel.com>
      Cc: Josh Poimboeuf <jpoimboe@redhat.com>
      Cc: Juergen Gross <jgross@suse.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Paul Jackson <pj@sgi.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Rafael J. Wysocki <rjw@sisk.pl>
      Cc: Tejun Heo <tj@kernel.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Wei Yang <richard.weiyang@gmail.com>
      Cc: Yinghai Lu <yinghai@kernel.org>
      Cc: linux-kernel@vger.kernel.org
      Signed-off-by: NIngo Molnar <mingo@kernel.org>
      7b80ba55
    • I
      x86/boot/e820: Introduce arch/x86/include/asm/e820/types.h · 70a9d818
      Ingo Molnar 提交于
      First baby steps towards saner e820 headers: create an exact copy of
      arch/x86/include/uapi/asm/e820.h and use it from the asm/e820.h file.
      
      No other changes - this is done to decouple the code from UAPI headers,
      plus to make sure that subsequent modifications to the file can be more
      clearly seen.
      
      The plan is to keep the old UAPI header in place but the kernel won't
      use it anymore - and after some time we'll try to remove it. (User-space
      tools better have local copies of headers anyway, instead of relying
      on kernel headers.)
      
      This gives the kernel the freedom to reorganize the e820 code.
      
      Cc: Alex Thorlton <athorlton@sgi.com>
      Cc: Andy Lutomirski <luto@kernel.org>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Dan Williams <dan.j.williams@intel.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Huang, Ying <ying.huang@intel.com>
      Cc: Josh Poimboeuf <jpoimboe@redhat.com>
      Cc: Juergen Gross <jgross@suse.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Paul Jackson <pj@sgi.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Rafael J. Wysocki <rjw@sisk.pl>
      Cc: Tejun Heo <tj@kernel.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Wei Yang <richard.weiyang@gmail.com>
      Cc: Yinghai Lu <yinghai@kernel.org>
      Cc: linux-kernel@vger.kernel.org
      Signed-off-by: NIngo Molnar <mingo@kernel.org>
      70a9d818
  2. 12 1月, 2017 2 次提交
    • J
      x86/unwind: Include __schedule() in stack traces · 2c96b2fe
      Josh Poimboeuf 提交于
      In the following commit:
      
        0100301b ("sched/x86: Rewrite the switch_to() code")
      
      ... the layout of the 'inactive_task_frame' struct was designed to have
      a frame pointer header embedded in it, so that the unwinder could use
      the 'bp' and 'ret_addr' fields to report __schedule() on the stack (or
      ret_from_fork() for newly forked tasks which haven't actually run yet).
      
      Finish the job by changing get_frame_pointer() to return a pointer to
      inactive_task_frame's 'bp' field rather than 'bp' itself.  This allows
      the unwinder to start one frame higher on the stack, so that it properly
      reports __schedule().
      Reported-by: NMiroslav Benes <mbenes@suse.cz>
      Signed-off-by: NJosh Poimboeuf <jpoimboe@redhat.com>
      Cc: Andy Lutomirski <luto@amacapital.net>
      Cc: Andy Lutomirski <luto@kernel.org>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Dave Jones <davej@codemonkey.org.uk>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: Dmitry Vyukov <dvyukov@google.com>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Link: http://lkml.kernel.org/r/598e9f7505ed0aba86e8b9590aa528c6c7ae8dcd.1483978430.git.jpoimboe@redhat.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
      2c96b2fe
    • J
      x86/unwind: Disable KASAN checks for non-current tasks · 84936118
      Josh Poimboeuf 提交于
      There are a handful of callers to save_stack_trace_tsk() and
      show_stack() which try to unwind the stack of a task other than current.
      In such cases, it's remotely possible that the task is running on one
      CPU while the unwinder is reading its stack from another CPU, causing
      the unwinder to see stack corruption.
      
      These cases seem to be mostly harmless.  The unwinder has checks which
      prevent it from following bad pointers beyond the bounds of the stack.
      So it's not really a bug as long as the caller understands that
      unwinding another task will not always succeed.
      
      In such cases, it's possible that the unwinder may read a KASAN-poisoned
      region of the stack.  Account for that by using READ_ONCE_NOCHECK() when
      reading the stack of another task.
      
      Use READ_ONCE() when reading the stack of the current task, since KASAN
      warnings can still be useful for finding bugs in that case.
      Reported-by: NDmitry Vyukov <dvyukov@google.com>
      Signed-off-by: NJosh Poimboeuf <jpoimboe@redhat.com>
      Cc: Andy Lutomirski <luto@amacapital.net>
      Cc: Andy Lutomirski <luto@kernel.org>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Dave Jones <davej@codemonkey.org.uk>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Miroslav Benes <mbenes@suse.cz>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Link: http://lkml.kernel.org/r/4c575eb288ba9f73d498dfe0acde2f58674598f1.1483978430.git.jpoimboe@redhat.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
      84936118
  3. 10 1月, 2017 2 次提交
  4. 06 1月, 2017 1 次提交
  5. 05 1月, 2017 1 次提交
  6. 30 12月, 2016 1 次提交
    • L
      mm: optimize PageWaiters bit use for unlock_page() · b91e1302
      Linus Torvalds 提交于
      In commit 62906027 ("mm: add PageWaiters indicating tasks are
      waiting for a page bit") Nick Piggin made our page locking no longer
      unconditionally touch the hashed page waitqueue, which not only helps
      performance in general, but is particularly helpful on NUMA machines
      where the hashed wait queues can bounce around a lot.
      
      However, the "clear lock bit atomically and then test the waiters bit"
      sequence turns out to be much more expensive than it needs to be,
      because you get a nasty stall when trying to access the same word that
      just got updated atomically.
      
      On architectures where locking is done with LL/SC, this would be trivial
      to fix with a new primitive that clears one bit and tests another
      atomically, but that ends up not working on x86, where the only atomic
      operations that return the result end up being cmpxchg and xadd.  The
      atomic bit operations return the old value of the same bit we changed,
      not the value of an unrelated bit.
      
      On x86, we could put the lock bit in the high bit of the byte, and use
      "xadd" with that bit (where the overflow ends up not touching other
      bits), and look at the other bits of the result.  However, an even
      simpler model is to just use a regular atomic "and" to clear the lock
      bit, and then the sign bit in eflags will indicate the resulting state
      of the unrelated bit #7.
      
      So by moving the PageWaiters bit up to bit #7, we can atomically clear
      the lock bit and test the waiters bit on x86 too.  And architectures
      with LL/SC (which is all the usual RISC suspects), the particular bit
      doesn't matter, so they are fine with this approach too.
      
      This avoids the extra access to the same atomic word, and thus avoids
      the costly stall at page unlock time.
      
      The only downside is that the interface ends up being a bit odd and
      specialized: clear a bit in a byte, and test the sign bit.  Nick doesn't
      love the resulting name of the new primitive, but I'd rather make the
      name be descriptive and very clear about the limitation imposed by
      trying to work across all relevant architectures than make it be some
      generic thing that doesn't make the odd semantics explicit.
      
      So this introduces the new architecture primitive
      
          clear_bit_unlock_is_negative_byte();
      
      and adds the trivial implementation for x86.  We have a generic
      non-optimized fallback (that just does a "clear_bit()"+"test_bit(7)"
      combination) which can be overridden by any architecture that can do
      better.  According to Nick, Power has the same hickup x86 has, for
      example, but some other architectures may not even care.
      
      All these optimizations mean that my page locking stress-test (which is
      just executing a lot of small short-lived shell scripts: "make test" in
      the git source tree) no longer makes our page locking look horribly bad.
      Before all these optimizations, just the unlock_page() costs were just
      over 3% of all CPU overhead on "make test".  After this, it's down to
      0.66%, so just a quarter of the cost it used to be.
      
      (The difference on NUMA is bigger, but there this micro-optimization is
      likely less noticeable, since the big issue on NUMA was not the accesses
      to 'struct page', but the waitqueue accesses that were already removed
      by Nick's earlier commit).
      Acked-by: NNick Piggin <npiggin@gmail.com>
      Cc: Dave Hansen <dave.hansen@linux.intel.com>
      Cc: Bob Peterson <rpeterso@redhat.com>
      Cc: Steven Whitehouse <swhiteho@redhat.com>
      Cc: Andrew Lutomirski <luto@kernel.org>
      Cc: Andreas Gruenbacher <agruenba@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Mel Gorman <mgorman@techsingularity.net>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      b91e1302
  7. 28 12月, 2016 1 次提交
  8. 25 12月, 2016 2 次提交
  9. 19 12月, 2016 6 次提交