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author | Linus Torvalds <torvalds@linux-foundation.org> | 2015-09-03 16:27:01 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2015-09-03 16:27:01 -0700 |
commit | c706c7eb0d08098f0d768aeef945d7cf1f8858b4 (patch) | |
tree | c629c9705514b70dd3e8f8dc67fa8d849871886c /arch/arm/kernel/entry-common.S | |
parent | 79b0691d0c1d3d4a976e3304a1512e6eca9671ec (diff) | |
parent | 3ff32a0def6e0d2e21a6c5ad1b00726592774018 (diff) |
Merge branch 'for-linus' of git://ftp.arm.linux.org.uk/~rmk/linux-arm
Pull ARM development updates from Russell King:
"Included in this update:
- moving PSCI code from ARM64/ARM to drivers/
- removal of some architecture internals from global kernel view
- addition of software based "privileged no access" support using the
old domains register to turn off the ability for kernel
loads/stores to access userspace. Only the proper accessors will
be usable.
- addition of early fixup support for early console
- re-addition (and reimplementation) of OMAP special interconnect
barrier
- removal of finish_arch_switch()
- only expose cpuX/online in sysfs if hotpluggable
- a number of code cleanups"
* 'for-linus' of git://ftp.arm.linux.org.uk/~rmk/linux-arm: (41 commits)
ARM: software-based priviledged-no-access support
ARM: entry: provide uaccess assembly macro hooks
ARM: entry: get rid of multiple macro definitions
ARM: 8421/1: smp: Collapse arch_cpu_idle_dead() into cpu_die()
ARM: uaccess: provide uaccess_save_and_enable() and uaccess_restore()
ARM: mm: improve do_ldrd_abort macro
ARM: entry: ensure that IRQs are enabled when calling syscall_trace_exit()
ARM: entry: efficiency cleanups
ARM: entry: get rid of asm_trace_hardirqs_on_cond
ARM: uaccess: simplify user access assembly
ARM: domains: remove DOMAIN_TABLE
ARM: domains: keep vectors in separate domain
ARM: domains: get rid of manager mode for user domain
ARM: domains: move initial domain setting value to asm/domains.h
ARM: domains: provide domain_mask()
ARM: domains: switch to keeping domain value in register
ARM: 8419/1: dma-mapping: harmonize definition of DMA_ERROR_CODE
ARM: 8417/1: refactor bitops functions with BIT_MASK() and BIT_WORD()
ARM: 8416/1: Feroceon: use of_iomap() to map register base
ARM: 8415/1: early fixmap support for earlycon
...
Diffstat (limited to 'arch/arm/kernel/entry-common.S')
-rw-r--r-- | arch/arm/kernel/entry-common.S | 63 |
1 files changed, 47 insertions, 16 deletions
diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S index b48dd4f37f80..30a7228eaceb 100644 --- a/arch/arm/kernel/entry-common.S +++ b/arch/arm/kernel/entry-common.S @@ -24,35 +24,55 @@ .align 5 +#if !(IS_ENABLED(CONFIG_TRACE_IRQFLAGS) || IS_ENABLED(CONFIG_CONTEXT_TRACKING)) /* - * This is the fast syscall return path. We do as little as - * possible here, and this includes saving r0 back into the SVC - * stack. + * This is the fast syscall return path. We do as little as possible here, + * such as avoiding writing r0 to the stack. We only use this path if we + * have tracing and context tracking disabled - the overheads from those + * features make this path too inefficient. */ ret_fast_syscall: UNWIND(.fnstart ) UNWIND(.cantunwind ) - disable_irq @ disable interrupts + disable_irq_notrace @ disable interrupts ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing - tst r1, #_TIF_SYSCALL_WORK - bne __sys_trace_return - tst r1, #_TIF_WORK_MASK + tst r1, #_TIF_SYSCALL_WORK | _TIF_WORK_MASK bne fast_work_pending - asm_trace_hardirqs_on /* perform architecture specific actions before user return */ arch_ret_to_user r1, lr - ct_user_enter restore_user_regs fast = 1, offset = S_OFF UNWIND(.fnend ) +ENDPROC(ret_fast_syscall) -/* - * Ok, we need to do extra processing, enter the slow path. - */ + /* Ok, we need to do extra processing, enter the slow path. */ fast_work_pending: str r0, [sp, #S_R0+S_OFF]! @ returned r0 -work_pending: + /* fall through to work_pending */ +#else +/* + * The "replacement" ret_fast_syscall for when tracing or context tracking + * is enabled. As we will need to call out to some C functions, we save + * r0 first to avoid needing to save registers around each C function call. + */ +ret_fast_syscall: + UNWIND(.fnstart ) + UNWIND(.cantunwind ) + str r0, [sp, #S_R0 + S_OFF]! @ save returned r0 + disable_irq_notrace @ disable interrupts + ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing + tst r1, #_TIF_SYSCALL_WORK | _TIF_WORK_MASK + beq no_work_pending + UNWIND(.fnend ) +ENDPROC(ret_fast_syscall) + + /* Slower path - fall through to work_pending */ +#endif + + tst r1, #_TIF_SYSCALL_WORK + bne __sys_trace_return_nosave +slow_work_pending: mov r0, sp @ 'regs' mov r2, why @ 'syscall' bl do_work_pending @@ -65,16 +85,19 @@ ENDPROC(ret_fast_syscall) /* * "slow" syscall return path. "why" tells us if this was a real syscall. + * IRQs may be enabled here, so always disable them. Note that we use the + * "notrace" version to avoid calling into the tracing code unnecessarily. + * do_work_pending() will update this state if necessary. */ ENTRY(ret_to_user) ret_slow_syscall: - disable_irq @ disable interrupts + disable_irq_notrace @ disable interrupts ENTRY(ret_to_user_from_irq) ldr r1, [tsk, #TI_FLAGS] tst r1, #_TIF_WORK_MASK - bne work_pending + bne slow_work_pending no_work_pending: - asm_trace_hardirqs_on + asm_trace_hardirqs_on save = 0 /* perform architecture specific actions before user return */ arch_ret_to_user r1, lr @@ -174,6 +197,8 @@ ENTRY(vector_swi) USER( ldr scno, [lr, #-4] ) @ get SWI instruction #endif + uaccess_disable tbl + adr tbl, sys_call_table @ load syscall table pointer #if defined(CONFIG_OABI_COMPAT) @@ -252,6 +277,12 @@ __sys_trace_return: bl syscall_trace_exit b ret_slow_syscall +__sys_trace_return_nosave: + enable_irq_notrace + mov r0, sp + bl syscall_trace_exit + b ret_slow_syscall + .align 5 #ifdef CONFIG_ALIGNMENT_TRAP .type __cr_alignment, #object |