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linux/arch/cris/arch-v32/mm/mmu.S
Greg Kroah-Hartman b24413180f License cleanup: add SPDX GPL-2.0 license identifier to files with no license 
Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.

By default all files without license information are under the default
license of the kernel, which is GPL version 2.

Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier.  The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.

How this work was done:

Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
 - file had no licensing information it it.
 - file was a */uapi/* one with no licensing information in it,
 - file was a */uapi/* one with existing licensing information,

Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.

The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne.  Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.

The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed.  Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.

Criteria used to select files for SPDX license identifier tagging was:
 - Files considered eligible had to be source code files.
 - Make and config files were included as candidates if they contained >5
   lines of source
 - File already had some variant of a license header in it (even if <5
   lines).

All documentation files were explicitly excluded.

The following heuristics were used to determine which SPDX license
identifiers to apply.

 - when both scanners couldn't find any license traces, file was
   considered to have no license information in it, and the top level
   COPYING file license applied.

   For non */uapi/* files that summary was:

   SPDX license identifier                            # files
   ---------------------------------------------------|-------
   GPL-2.0                                              11139

   and resulted in the first patch in this series.

   If that file was a */uapi/* path one, it was "GPL-2.0 WITH
   Linux-syscall-note" otherwise it was "GPL-2.0".  Results of that was:

   SPDX license identifier                            # files
   ---------------------------------------------------|-------
   GPL-2.0 WITH Linux-syscall-note                        930

   and resulted in the second patch in this series.

 - if a file had some form of licensing information in it, and was one
   of the */uapi/* ones, it was denoted with the Linux-syscall-note if
   any GPL family license was found in the file or had no licensing in
   it (per prior point).  Results summary:

   SPDX license identifier                            # files
   ---------------------------------------------------|------
   GPL-2.0 WITH Linux-syscall-note                       270
   GPL-2.0+ WITH Linux-syscall-note                      169
   ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause)    21
   ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause)    17
   LGPL-2.1+ WITH Linux-syscall-note                      15
   GPL-1.0+ WITH Linux-syscall-note                       14
   ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause)    5
   LGPL-2.0+ WITH Linux-syscall-note                       4
   LGPL-2.1 WITH Linux-syscall-note                        3
   ((GPL-2.0 WITH Linux-syscall-note) OR MIT)              3
   ((GPL-2.0 WITH Linux-syscall-note) AND MIT)             1

   and that resulted in the third patch in this series.

 - when the two scanners agreed on the detected license(s), that became
   the concluded license(s).

 - when there was disagreement between the two scanners (one detected a
   license but the other didn't, or they both detected different
   licenses) a manual inspection of the file occurred.

 - In most cases a manual inspection of the information in the file
   resulted in a clear resolution of the license that should apply (and
   which scanner probably needed to revisit its heuristics).

 - When it was not immediately clear, the license identifier was
   confirmed with lawyers working with the Linux Foundation.

 - If there was any question as to the appropriate license identifier,
   the file was flagged for further research and to be revisited later
   in time.

In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.

Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights.  The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.

Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.

In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.

Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
 - a full scancode scan run, collecting the matched texts, detected
   license ids and scores
 - reviewing anything where there was a license detected (about 500+
   files) to ensure that the applied SPDX license was correct
 - reviewing anything where there was no detection but the patch license
   was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
   SPDX license was correct

This produced a worksheet with 20 files needing minor correction.  This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.

These .csv files were then reviewed by Greg.  Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected.  This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.)  Finally Greg ran the script using the .csv files to
generate the patches.

Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-02 11:10:55 +01:00

212 lines
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; SPDX-License-Identifier: GPL-2.0
; WARNING : The refill handler has been modified, see below !!!
/*
* Copyright (C) 2003 Axis Communications AB
*
* Authors: Mikael Starvik (starvik@axis.com)
*
* Code for the fault low-level handling routines.
*
*/
#include <asm/page.h>
#include <asm/pgtable.h>
; Save all register. Must save in same order as struct pt_regs.
.macro SAVE_ALL
subq 12, $sp
move $erp, [$sp]
subq 4, $sp
move $srp, [$sp]
subq 4, $sp
move $ccs, [$sp]
subq 4, $sp
move $spc, [$sp]
subq 4, $sp
move $mof, [$sp]
subq 4, $sp
move $srs, [$sp]
subq 4, $sp
move.d $acr, [$sp]
subq 14*4, $sp
movem $r13, [$sp]
subq 4, $sp
move.d $r10, [$sp]
.endm
; Bus fault handler. Extracts relevant information and calls mm subsystem
; to handle the fault.
.macro MMU_BUS_FAULT_HANDLER handler, mmu, we, ex
.globl \handler
.type \handler,"function"
\handler:
SAVE_ALL
move \mmu, $srs ; Select MMU support register bank
move.d $sp, $r11 ; regs
moveq 1, $r12 ; protection fault
moveq \we, $r13 ; write exception?
orq \ex << 1, $r13 ; execute?
move $s3, $r10 ; rw_mm_cause
and.d ~8191, $r10 ; Get faulting page start address
jsr do_page_fault
nop
ba ret_from_intr
nop
.size \handler, . - \handler
.endm
; Refill handler. Three cases may occur:
; 1. PMD and PTE exists in mm subsystem but not in TLB
; 2. PMD exists but not PTE
; 3. PMD doesn't exist
; The code below handles case 1 and calls the mm subsystem for case 2 and 3.
; Do not touch this code without very good reasons and extensive testing.
; Note that the code is optimized to minimize stalls (makes the code harder
; to read).
;
; WARNING !!!
; Modified by Mikael Asker 060725: added a workaround for strange TLB
; behavior. If the same PTE is present in more than one set, the TLB
; doesn't recognize it and we get stuck in a loop of refill exceptions.
; The workaround detects such loops and exits them by flushing
; the TLB contents. The problem and workaround were verified
; in VCS by Mikael Starvik.
;
; Each page is 8 KB. Each PMD holds 8192/4 PTEs (each PTE is 4 bytes) so each
; PMD holds 16 MB of virtual memory.
; Bits 0-12 : Offset within a page
; Bits 13-23 : PTE offset within a PMD
; Bits 24-31 : PMD offset within the PGD
.macro MMU_REFILL_HANDLER handler, mmu
.data
1: .dword 0 ; refill_count
; == 0 <=> last_refill_cause is invalid
2: .dword 0 ; last_refill_cause
.text
.globl \handler
.type \handler, "function"
\handler:
subq 4, $sp
; (The pipeline stalls for one cycle; $sp used as address in the next cycle.)
move $srs, [$sp]
subq 4, $sp
move \mmu, $srs ; Select MMU support register bank
move.d $acr, [$sp]
subq 12, $sp
move.d 1b, $acr ; Point to refill_count
movem $r2, [$sp]
test.d [$acr] ; refill_count == 0 ?
beq 5f ; yes, last_refill_cause is invalid
move.d $acr, $r1
; last_refill_cause is valid, investigate cause
addq 4, $r1 ; Point to last_refill_cause
move $s3, $r0 ; Get rw_mm_cause
move.d [$r1], $r2 ; Get last_refill_cause
cmp.d $r0, $r2 ; rw_mm_cause == last_refill_cause ?
beq 6f ; yes, increment count
moveq 1, $r2
; rw_mm_cause != last_refill_cause
move.d $r2, [$acr] ; refill_count = 1
move.d $r0, [$r1] ; last_refill_cause = rw_mm_cause
3: ; Probably not in a loop, continue normal processing
move.d current_pgd, $acr ; PGD
; Look up PMD in PGD
lsrq 24, $r0 ; Get PMD index into PGD (bit 24-31)
move.d [$acr], $acr ; PGD for the current process
addi $r0.d, $acr, $acr
move $s3, $r0 ; rw_mm_cause
move.d [$acr], $acr ; Get PMD
beq 8f
; Look up PTE in PMD
lsrq PAGE_SHIFT, $r0
and.w PAGE_MASK, $acr ; Remove PMD flags
and.d 0x7ff, $r0 ; Get PTE index into PMD (bit 13-23)
addi $r0.d, $acr, $acr
move.d [$acr], $acr ; Get PTE
beq 9f
movem [$sp], $r2 ; Restore r0-r2 in delay slot
addq 12, $sp
; Store in TLB
move $acr, $s5
4: ; Return
move.d [$sp+], $acr
move [$sp], $srs
addq 4, $sp
rete
rfe
5: ; last_refill_cause is invalid
moveq 1, $r2
addq 4, $r1 ; Point to last_refill_cause
move.d $r2, [$acr] ; refill_count = 1
move $s3, $r0 ; Get rw_mm_cause
ba 3b ; Continue normal processing
move.d $r0,[$r1] ; last_refill_cause = rw_mm_cause
6: ; rw_mm_cause == last_refill_cause
move.d [$acr], $r2 ; Get refill_count
cmpq 4, $r2 ; refill_count > 4 ?
bhi 7f ; yes
addq 1, $r2 ; refill_count++
ba 3b ; Continue normal processing
move.d $r2, [$acr]
7: ; refill_count > 4, error
move.d $acr, $r0 ; Save pointer to refill_count
clear.d [$r0] ; refill_count = 0
;; rewind the short stack
movem [$sp], $r2 ; Restore r0-r2
addq 12, $sp
move.d [$sp+], $acr
move [$sp], $srs
addq 4, $sp
;; Keep it simple (slow), save all the regs.
SAVE_ALL
jsr __flush_tlb_all
nop
ba ret_from_intr ; Return
nop
8: ; PMD missing, let the mm subsystem fix it up.
movem [$sp], $r2 ; Restore r0-r2
9: ; PTE missing, let the mm subsystem fix it up.
addq 12, $sp
move.d [$sp+], $acr
move [$sp], $srs
addq 4, $sp
SAVE_ALL
move \mmu, $srs
move.d $sp, $r11 ; regs
clear.d $r12 ; Not a protection fault
move.w PAGE_MASK, $acr
move $s3, $r10 ; rw_mm_cause
btstq 9, $r10 ; Check if write access
smi $r13
and.w PAGE_MASK, $r10 ; Get VPN (virtual address)
jsr do_page_fault
and.w $acr, $r10
; Return
ba ret_from_intr
nop
.size \handler, . - \handler
.endm
; This is the MMU bus fault handlers.
MMU_REFILL_HANDLER i_mmu_refill, 1
MMU_BUS_FAULT_HANDLER i_mmu_invalid, 1, 0, 0
MMU_BUS_FAULT_HANDLER i_mmu_access, 1, 0, 0
MMU_BUS_FAULT_HANDLER i_mmu_execute, 1, 0, 1
MMU_REFILL_HANDLER d_mmu_refill, 2
MMU_BUS_FAULT_HANDLER d_mmu_invalid, 2, 0, 0
MMU_BUS_FAULT_HANDLER d_mmu_access, 2, 0, 0
MMU_BUS_FAULT_HANDLER d_mmu_write, 2, 1, 0
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