summaryrefslogtreecommitdiffstats
path: root/arch/arm/kernel/entry-armv.S
diff options
context:
space:
mode:
Diffstat (limited to 'arch/arm/kernel/entry-armv.S')
-rw-r--r--arch/arm/kernel/entry-armv.S99
1 files changed, 96 insertions, 3 deletions
diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index 63f7907c4c3c..9be97deca215 100644
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -383,7 +383,7 @@ ENDPROC(__pabt_svc)
.endm
.macro kuser_cmpxchg_check
-#if __LINUX_ARM_ARCH__ < 6 && !defined(CONFIG_NEEDS_SYSCALL_FOR_CMPXCHG)
+#if !defined(CONFIG_CPU_32v6K) && !defined(CONFIG_NEEDS_SYSCALL_FOR_CMPXCHG)
#ifndef CONFIG_MMU
#warning "NPTL on non MMU needs fixing"
#else
@@ -392,7 +392,7 @@ ENDPROC(__pabt_svc)
@ perform a quick test inline since it should be false
@ 99.9999% of the time. The rest is done out of line.
cmp r2, #TASK_SIZE
- blhs kuser_cmpxchg_fixup
+ blhs kuser_cmpxchg64_fixup
#endif
#endif
.endm
@@ -775,6 +775,99 @@ ENDPROC(__switch_to)
.globl __kuser_helper_start
__kuser_helper_start:
+/*
+ * Due to the length of some sequences, __kuser_cmpxchg64 spans 2 regular
+ * kuser "slots", therefore 0xffff0f80 is not used as a valid entry point.
+ */
+
+__kuser_cmpxchg64: @ 0xffff0f60
+
+#if defined(CONFIG_NEEDS_SYSCALL_FOR_CMPXCHG)
+
+ /*
+ * Poor you. No fast solution possible...
+ * The kernel itself must perform the operation.
+ * A special ghost syscall is used for that (see traps.c).
+ */
+ stmfd sp!, {r7, lr}
+ ldr r7, 1f @ it's 20 bits
+ swi __ARM_NR_cmpxchg64
+ ldmfd sp!, {r7, pc}
+1: .word __ARM_NR_cmpxchg64
+
+#elif defined(CONFIG_CPU_32v6K)
+
+ stmfd sp!, {r4, r5, r6, r7}
+ ldrd r4, r5, [r0] @ load old val
+ ldrd r6, r7, [r1] @ load new val
+ smp_dmb arm
+1: ldrexd r0, r1, [r2] @ load current val
+ eors r3, r0, r4 @ compare with oldval (1)
+ eoreqs r3, r1, r5 @ compare with oldval (2)
+ strexdeq r3, r6, r7, [r2] @ store newval if eq
+ teqeq r3, #1 @ success?
+ beq 1b @ if no then retry
+ smp_dmb arm
+ rsbs r0, r3, #0 @ set returned val and C flag
+ ldmfd sp!, {r4, r5, r6, r7}
+ bx lr
+
+#elif !defined(CONFIG_SMP)
+
+#ifdef CONFIG_MMU
+
+ /*
+ * The only thing that can break atomicity in this cmpxchg64
+ * implementation is either an IRQ or a data abort exception
+ * causing another process/thread to be scheduled in the middle of
+ * the critical sequence. The same strategy as for cmpxchg is used.
+ */
+ stmfd sp!, {r4, r5, r6, lr}
+ ldmia r0, {r4, r5} @ load old val
+ ldmia r1, {r6, lr} @ load new val
+1: ldmia r2, {r0, r1} @ load current val
+ eors r3, r0, r4 @ compare with oldval (1)
+ eoreqs r3, r1, r5 @ compare with oldval (2)
+2: stmeqia r2, {r6, lr} @ store newval if eq
+ rsbs r0, r3, #0 @ set return val and C flag
+ ldmfd sp!, {r4, r5, r6, pc}
+
+ .text
+kuser_cmpxchg64_fixup:
+ @ Called from kuser_cmpxchg_fixup.
+ @ r2 = address of interrupted insn (must be preserved).
+ @ sp = saved regs. r7 and r8 are clobbered.
+ @ 1b = first critical insn, 2b = last critical insn.
+ @ If r2 >= 1b and r2 <= 2b then saved pc_usr is set to 1b.
+ mov r7, #0xffff0fff
+ sub r7, r7, #(0xffff0fff - (0xffff0f60 + (1b - __kuser_cmpxchg64)))
+ subs r8, r2, r7
+ rsbcss r8, r8, #(2b - 1b)
+ strcs r7, [sp, #S_PC]
+#if __LINUX_ARM_ARCH__ < 6
+ bcc kuser_cmpxchg32_fixup
+#endif
+ mov pc, lr
+ .previous
+
+#else
+#warning "NPTL on non MMU needs fixing"
+ mov r0, #-1
+ adds r0, r0, #0
+ usr_ret lr
+#endif
+
+#else
+#error "incoherent kernel configuration"
+#endif
+
+ /* pad to next slot */
+ .rept (16 - (. - __kuser_cmpxchg64)/4)
+ .word 0
+ .endr
+
+ .align 5
+
__kuser_memory_barrier: @ 0xffff0fa0
smp_dmb arm
usr_ret lr
@@ -816,7 +909,7 @@ __kuser_cmpxchg: @ 0xffff0fc0
usr_ret lr
.text
-kuser_cmpxchg_fixup:
+kuser_cmpxchg32_fixup:
@ Called from kuser_cmpxchg_check macro.
@ r2 = address of interrupted insn (must be preserved).
@ sp = saved regs. r7 and r8 are clobbered.