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alistair23-linux/arch/arm/kernel/entry-header.S

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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>
2017-11-01 08:07:57 -06:00
/* SPDX-License-Identifier: GPL-2.0 */
#include <linux/init.h>
#include <linux/linkage.h>
#include <asm/assembler.h>
#include <asm/asm-offsets.h>
#include <asm/errno.h>
#include <asm/thread_info.h>
#include <asm/uaccess-asm.h>
#include <asm/v7m.h>
@ Bad Abort numbers
@ -----------------
@
#define BAD_PREFETCH 0
#define BAD_DATA 1
#define BAD_ADDREXCPTN 2
#define BAD_IRQ 3
#define BAD_UNDEFINSTR 4
@
@ Most of the stack format comes from struct pt_regs, but with
@ the addition of 8 bytes for storing syscall args 5 and 6.
@ This _must_ remain a multiple of 8 for EABI.
@
#define S_OFF 8
/*
* The SWI code relies on the fact that R0 is at the bottom of the stack
* (due to slow/fast restore user regs).
*/
#if S_R0 != 0
#error "Please fix"
#endif
.macro zero_fp
#ifdef CONFIG_FRAME_POINTER
mov fp, #0
#endif
.endm
#ifdef CONFIG_ALIGNMENT_TRAP
#define ATRAP(x...) x
#else
#define ATRAP(x...)
#endif
.macro alignment_trap, rtmp1, rtmp2, label
#ifdef CONFIG_ALIGNMENT_TRAP
mrc p15, 0, \rtmp2, c1, c0, 0
ldr \rtmp1, \label
ldr \rtmp1, [\rtmp1]
teq \rtmp1, \rtmp2
mcrne p15, 0, \rtmp1, c1, c0, 0
#endif
.endm
#ifdef CONFIG_CPU_V7M
/*
* ARMv7-M exception entry/exit macros.
*
* xPSR, ReturnAddress(), LR (R14), R12, R3, R2, R1, and R0 are
* automatically saved on the current stack (32 words) before
* switching to the exception stack (SP_main).
*
* If exception is taken while in user mode, SP_main is
* empty. Otherwise, SP_main is aligned to 64 bit automatically
* (CCR.STKALIGN set).
*
* Linux assumes that the interrupts are disabled when entering an
* exception handler and it may BUG if this is not the case. Interrupts
* are disabled during entry and reenabled in the exit macro.
*
* v7m_exception_slow_exit is used when returning from SVC or PendSV.
* When returning to kernel mode, we don't return from exception.
*/
.macro v7m_exception_entry
@ determine the location of the registers saved by the core during
@ exception entry. Depending on the mode the cpu was in when the
@ exception happend that is either on the main or the process stack.
@ Bit 2 of EXC_RETURN stored in the lr register specifies which stack
@ was used.
tst lr, #EXC_RET_STACK_MASK
mrsne r12, psp
moveq r12, sp
@ we cannot rely on r0-r3 and r12 matching the value saved in the
@ exception frame because of tail-chaining. So these have to be
@ reloaded.
ldmia r12!, {r0-r3}
@ Linux expects to have irqs off. Do it here before taking stack space
cpsid i
sub sp, #PT_REGS_SIZE-S_IP
stmdb sp!, {r0-r11}
@ load saved r12, lr, return address and xPSR.
@ r0-r7 are used for signals and never touched from now on. Clobbering
@ r8-r12 is OK.
mov r9, r12
ldmia r9!, {r8, r10-r12}
@ calculate the original stack pointer value.
@ r9 currently points to the memory location just above the auto saved
@ xPSR.
@ The cpu might automatically 8-byte align the stack. Bit 9
@ of the saved xPSR specifies if stack aligning took place. In this case
@ another 32-bit value is included in the stack.
tst r12, V7M_xPSR_FRAMEPTRALIGN
addne r9, r9, #4
@ store saved r12 using str to have a register to hold the base for stm
str r8, [sp, #S_IP]
add r8, sp, #S_SP
@ store r13-r15, xPSR
stmia r8!, {r9-r12}
@ store old_r0
str r0, [r8]
.endm
/*
* PENDSV and SVCALL are configured to have the same exception
* priorities. As a kernel thread runs at SVCALL execution priority it
* can never be preempted and so we will never have to return to a
* kernel thread here.
*/
.macro v7m_exception_slow_exit ret_r0
cpsid i
ldr lr, =exc_ret
ldr lr, [lr]
@ read original r12, sp, lr, pc and xPSR
add r12, sp, #S_IP
ldmia r12, {r1-r5}
@ an exception frame is always 8-byte aligned. To tell the hardware if
@ the sp to be restored is aligned or not set bit 9 of the saved xPSR
@ accordingly.
tst r2, #4
subne r2, r2, #4
orrne r5, V7M_xPSR_FRAMEPTRALIGN
biceq r5, V7M_xPSR_FRAMEPTRALIGN
@ ensure bit 0 is cleared in the PC, otherwise behaviour is
@ unpredictable
bic r4, #1
@ write basic exception frame
stmdb r2!, {r1, r3-r5}
ldmia sp, {r1, r3-r5}
.if \ret_r0
stmdb r2!, {r0, r3-r5}
.else
stmdb r2!, {r1, r3-r5}
.endif
@ restore process sp
msr psp, r2
@ restore original r4-r11
ldmia sp!, {r0-r11}
@ restore main sp
add sp, sp, #PT_REGS_SIZE-S_IP
cpsie i
bx lr
.endm
#endif /* CONFIG_CPU_V7M */
@
@ Store/load the USER SP and LR registers by switching to the SYS
@ mode. Useful in Thumb-2 mode where "stm/ldm rd, {sp, lr}^" is not
@ available. Should only be called from SVC mode
@
.macro store_user_sp_lr, rd, rtemp, offset = 0
mrs \rtemp, cpsr
eor \rtemp, \rtemp, #(SVC_MODE ^ SYSTEM_MODE)
msr cpsr_c, \rtemp @ switch to the SYS mode
str sp, [\rd, #\offset] @ save sp_usr
str lr, [\rd, #\offset + 4] @ save lr_usr
eor \rtemp, \rtemp, #(SVC_MODE ^ SYSTEM_MODE)
msr cpsr_c, \rtemp @ switch back to the SVC mode
.endm
.macro load_user_sp_lr, rd, rtemp, offset = 0
mrs \rtemp, cpsr
eor \rtemp, \rtemp, #(SVC_MODE ^ SYSTEM_MODE)
msr cpsr_c, \rtemp @ switch to the SYS mode
ldr sp, [\rd, #\offset] @ load sp_usr
ldr lr, [\rd, #\offset + 4] @ load lr_usr
eor \rtemp, \rtemp, #(SVC_MODE ^ SYSTEM_MODE)
msr cpsr_c, \rtemp @ switch back to the SVC mode
.endm
.macro svc_exit, rpsr, irq = 0
.if \irq != 0
@ IRQs already off
#ifdef CONFIG_TRACE_IRQFLAGS
@ The parent context IRQs must have been enabled to get here in
@ the first place, so there's no point checking the PSR I bit.
bl trace_hardirqs_on
#endif
.else
@ IRQs off again before pulling preserved data off the stack
disable_irq_notrace
#ifdef CONFIG_TRACE_IRQFLAGS
tst \rpsr, #PSR_I_BIT
bleq trace_hardirqs_on
tst \rpsr, #PSR_I_BIT
blne trace_hardirqs_off
#endif
.endif
uaccess_exit tsk, r0, r1
#ifndef CONFIG_THUMB2_KERNEL
@ ARM mode SVC restore
msr spsr_cxsf, \rpsr
#if defined(CONFIG_CPU_V6) || defined(CONFIG_CPU_32v6K)
@ We must avoid clrex due to Cortex-A15 erratum #830321
sub r0, sp, #4 @ uninhabited address
strex r1, r2, [r0] @ clear the exclusive monitor
#endif
ldmia sp, {r0 - pc}^ @ load r0 - pc, cpsr
#else
@ Thumb mode SVC restore
ldr lr, [sp, #S_SP] @ top of the stack
ldrd r0, r1, [sp, #S_LR] @ calling lr and pc
@ We must avoid clrex due to Cortex-A15 erratum #830321
strex r2, r1, [sp, #S_LR] @ clear the exclusive monitor
stmdb lr!, {r0, r1, \rpsr} @ calling lr and rfe context
ldmia sp, {r0 - r12}
mov sp, lr
ldr lr, [sp], #4
rfeia sp!
#endif
.endm
@
@ svc_exit_via_fiq - like svc_exit but switches to FIQ mode before exit
@
@ This macro acts in a similar manner to svc_exit but switches to FIQ
@ mode to restore the final part of the register state.
@
@ We cannot use the normal svc_exit procedure because that would
@ clobber spsr_svc (FIQ could be delivered during the first few
@ instructions of vector_swi meaning its contents have not been
@ saved anywhere).
@
@ Note that, unlike svc_exit, this macro also does not allow a caller
@ supplied rpsr. This is because the FIQ exceptions are not re-entrant
@ and the handlers cannot call into the scheduler (meaning the value
@ on the stack remains correct).
@
.macro svc_exit_via_fiq
uaccess_exit tsk, r0, r1
#ifndef CONFIG_THUMB2_KERNEL
@ ARM mode restore
mov r0, sp
ldmib r0, {r1 - r14} @ abort is deadly from here onward (it will
@ clobber state restored below)
msr cpsr_c, #FIQ_MODE | PSR_I_BIT | PSR_F_BIT
add r8, r0, #S_PC
ldr r9, [r0, #S_PSR]
msr spsr_cxsf, r9
ldr r0, [r0, #S_R0]
ldmia r8, {pc}^
#else
@ Thumb mode restore
add r0, sp, #S_R2
ldr lr, [sp, #S_LR]
ldr sp, [sp, #S_SP] @ abort is deadly from here onward (it will
@ clobber state restored below)
ldmia r0, {r2 - r12}
mov r1, #FIQ_MODE | PSR_I_BIT | PSR_F_BIT
msr cpsr_c, r1
sub r0, #S_R2
add r8, r0, #S_PC
ldmia r0, {r0 - r1}
rfeia r8
#endif
.endm
.macro restore_user_regs, fast = 0, offset = 0
uaccess_enable r1, isb=0
#ifndef CONFIG_THUMB2_KERNEL
@ ARM mode restore
mov r2, sp
ldr r1, [r2, #\offset + S_PSR] @ get calling cpsr
ldr lr, [r2, #\offset + S_PC]! @ get pc
tst r1, #PSR_I_BIT | 0x0f
bne 1f
msr spsr_cxsf, r1 @ save in spsr_svc
#if defined(CONFIG_CPU_V6) || defined(CONFIG_CPU_32v6K)
@ We must avoid clrex due to Cortex-A15 erratum #830321
strex r1, r2, [r2] @ clear the exclusive monitor
#endif
.if \fast
ldmdb r2, {r1 - lr}^ @ get calling r1 - lr
.else
ldmdb r2, {r0 - lr}^ @ get calling r0 - lr
.endif
mov r0, r0 @ ARMv5T and earlier require a nop
@ after ldm {}^
add sp, sp, #\offset + PT_REGS_SIZE
movs pc, lr @ return & move spsr_svc into cpsr
1: bug "Returning to usermode but unexpected PSR bits set?", \@
#elif defined(CONFIG_CPU_V7M)
@ V7M restore.
@ Note that we don't need to do clrex here as clearing the local
@ monitor is part of the exception entry and exit sequence.
.if \offset
add sp, #\offset
.endif
v7m_exception_slow_exit ret_r0 = \fast
#else
@ Thumb mode restore
mov r2, sp
load_user_sp_lr r2, r3, \offset + S_SP @ calling sp, lr
ldr r1, [sp, #\offset + S_PSR] @ get calling cpsr
ldr lr, [sp, #\offset + S_PC] @ get pc
add sp, sp, #\offset + S_SP
tst r1, #PSR_I_BIT | 0x0f
bne 1f
msr spsr_cxsf, r1 @ save in spsr_svc
@ We must avoid clrex due to Cortex-A15 erratum #830321
strex r1, r2, [sp] @ clear the exclusive monitor
.if \fast
ldmdb sp, {r1 - r12} @ get calling r1 - r12
.else
ldmdb sp, {r0 - r12} @ get calling r0 - r12
.endif
add sp, sp, #PT_REGS_SIZE - S_SP
movs pc, lr @ return & move spsr_svc into cpsr
1: bug "Returning to usermode but unexpected PSR bits set?", \@
#endif /* !CONFIG_THUMB2_KERNEL */
.endm
/*
* Context tracking subsystem. Used to instrument transitions
* between user and kernel mode.
*/
.macro ct_user_exit, save = 1
#ifdef CONFIG_CONTEXT_TRACKING
.if \save
stmdb sp!, {r0-r3, ip, lr}
bl context_tracking_user_exit
ldmia sp!, {r0-r3, ip, lr}
.else
bl context_tracking_user_exit
.endif
#endif
.endm
.macro ct_user_enter, save = 1
#ifdef CONFIG_CONTEXT_TRACKING
.if \save
stmdb sp!, {r0-r3, ip, lr}
bl context_tracking_user_enter
ldmia sp!, {r0-r3, ip, lr}
.else
bl context_tracking_user_enter
.endif
#endif
.endm
.macro invoke_syscall, table, nr, tmp, ret, reload=0
#ifdef CONFIG_CPU_SPECTRE
mov \tmp, \nr
cmp \tmp, #NR_syscalls @ check upper syscall limit
movcs \tmp, #0
csdb
badr lr, \ret @ return address
.if \reload
add r1, sp, #S_R0 + S_OFF @ pointer to regs
ldmiacc r1, {r0 - r6} @ reload r0-r6
stmiacc sp, {r4, r5} @ update stack arguments
.endif
ldrcc pc, [\table, \tmp, lsl #2] @ call sys_* routine
#else
cmp \nr, #NR_syscalls @ check upper syscall limit
badr lr, \ret @ return address
.if \reload
add r1, sp, #S_R0 + S_OFF @ pointer to regs
ldmiacc r1, {r0 - r6} @ reload r0-r6
stmiacc sp, {r4, r5} @ update stack arguments
.endif
ldrcc pc, [\table, \nr, lsl #2] @ call sys_* routine
#endif
.endm
/*
* These are the registers used in the syscall handler, and allow us to
* have in theory up to 7 arguments to a function - r0 to r6.
*
* r7 is reserved for the system call number for thumb mode.
*
* Note that tbl == why is intentional.
*
* We must set at least "tsk" and "why" when calling ret_with_reschedule.
*/
scno .req r7 @ syscall number
tbl .req r8 @ syscall table pointer
why .req r8 @ Linux syscall (!= 0)
tsk .req r9 @ current thread_info