ARC: Increase readability of entry handlers
* use artificial PUSH/POP contructs for CORE Reg save/restore to stack
* use artificial PUSHAX/POPAX contructs for Auxiliary Space regs
* macro'ize multiple copies of callee-reg-save/restore (SAVE_R13_TO_R24)
* use BIC insn for inverse-and operation
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
diff --git a/arch/arc/include/asm/entry.h b/arch/arc/include/asm/entry.h
index 820202a..5191945 100644
--- a/arch/arc/include/asm/entry.h
+++ b/arch/arc/include/asm/entry.h
@@ -50,150 +50,155 @@
* Eff Addr for load = [reg2]
*/
-/*--------------------------------------------------------------
- * Save caller saved registers (scratch registers) ( r0 - r12 )
- * Registers are pushed / popped in the order defined in struct ptregs
- * in asm/ptrace.h
- *-------------------------------------------------------------*/
-.macro SAVE_CALLER_SAVED
- st.a r0, [sp, -4]
- st.a r1, [sp, -4]
- st.a r2, [sp, -4]
- st.a r3, [sp, -4]
- st.a r4, [sp, -4]
- st.a r5, [sp, -4]
- st.a r6, [sp, -4]
- st.a r7, [sp, -4]
- st.a r8, [sp, -4]
- st.a r9, [sp, -4]
- st.a r10, [sp, -4]
- st.a r11, [sp, -4]
- st.a r12, [sp, -4]
+.macro PUSH reg
+ st.a \reg, [sp, -4]
+.endm
+
+.macro PUSHAX aux
+ lr r9, [\aux]
+ PUSH r9
+.endm
+
+.macro POP reg
+ ld.ab \reg, [sp, 4]
+.endm
+
+.macro POPAX aux
+ POP r9
+ sr r9, [\aux]
.endm
/*--------------------------------------------------------------
- * Restore caller saved registers (scratch registers)
+ * Helpers to save/restore Scratch Regs:
+ * used by Interrupt/Exception Prologue/Epilogue
*-------------------------------------------------------------*/
-.macro RESTORE_CALLER_SAVED
- ld.ab r12, [sp, 4]
- ld.ab r11, [sp, 4]
- ld.ab r10, [sp, 4]
- ld.ab r9, [sp, 4]
- ld.ab r8, [sp, 4]
- ld.ab r7, [sp, 4]
- ld.ab r6, [sp, 4]
- ld.ab r5, [sp, 4]
- ld.ab r4, [sp, 4]
- ld.ab r3, [sp, 4]
- ld.ab r2, [sp, 4]
- ld.ab r1, [sp, 4]
- ld.ab r0, [sp, 4]
+.macro SAVE_R0_TO_R12
+ PUSH r0
+ PUSH r1
+ PUSH r2
+ PUSH r3
+ PUSH r4
+ PUSH r5
+ PUSH r6
+ PUSH r7
+ PUSH r8
+ PUSH r9
+ PUSH r10
+ PUSH r11
+ PUSH r12
+.endm
+
+.macro RESTORE_R12_TO_R0
+ POP r12
+ POP r11
+ POP r10
+ POP r9
+ POP r8
+ POP r7
+ POP r6
+ POP r5
+ POP r4
+ POP r3
+ POP r2
+ POP r1
+ POP r0
+.endm
+
+/*--------------------------------------------------------------
+ * Helpers to save/restore callee-saved regs:
+ * used by several macros below
+ *-------------------------------------------------------------*/
+.macro SAVE_R13_TO_R24
+ PUSH r13
+ PUSH r14
+ PUSH r15
+ PUSH r16
+ PUSH r17
+ PUSH r18
+ PUSH r19
+ PUSH r20
+ PUSH r21
+ PUSH r22
+ PUSH r23
+ PUSH r24
+.endm
+
+.macro RESTORE_R24_TO_R13
+ POP r24
+ POP r23
+ POP r22
+ POP r21
+ POP r20
+ POP r19
+ POP r18
+ POP r17
+ POP r16
+ POP r15
+ POP r14
+ POP r13
.endm
/*--------------------------------------------------------------
- * Save callee saved registers (non scratch registers) ( r13 - r25 )
- * on kernel stack.
- * User mode callee regs need to be saved in case of
- * -fork and friends for replicating from parent to child
- * -before going into do_signal( ) for ptrace/core-dump
- * Special case handling is required for r25 in case it is used by kernel
- * for caching task ptr. Low level exception/ISR save user mode r25
- * into task->thread.user_r25. So it needs to be retrieved from there and
- * saved into kernel stack with rest of callee reg-file
+ * Collect User Mode callee regs as struct callee_regs - needed by
+ * fork/do_signal/unaligned-access-emulation.
+ * (By default only scratch regs are saved on entry to kernel)
+ *
+ * Special handling for r25 if used for caching Task Pointer.
+ * It would have been saved in task->thread.user_r25 already, but to keep
+ * the interface same it is copied into regular r25 placeholder in
+ * struct callee_regs.
*-------------------------------------------------------------*/
.macro SAVE_CALLEE_SAVED_USER
- st.a r13, [sp, -4]
- st.a r14, [sp, -4]
- st.a r15, [sp, -4]
- st.a r16, [sp, -4]
- st.a r17, [sp, -4]
- st.a r18, [sp, -4]
- st.a r19, [sp, -4]
- st.a r20, [sp, -4]
- st.a r21, [sp, -4]
- st.a r22, [sp, -4]
- st.a r23, [sp, -4]
- st.a r24, [sp, -4]
+
+ SAVE_R13_TO_R24
#ifdef CONFIG_ARC_CURR_IN_REG
; Retrieve orig r25 and save it on stack
ld r12, [r25, TASK_THREAD + THREAD_USER_R25]
st.a r12, [sp, -4]
#else
- st.a r25, [sp, -4]
+ PUSH r25
#endif
.endm
/*--------------------------------------------------------------
- * Save callee saved registers (non scratch registers) ( r13 - r25 )
- * kernel mode callee regs needed to be saved in case of context switch
- * If r25 is used for caching task pointer then that need not be saved
- * as it can be re-created from current task global
+ * Save kernel Mode callee regs at the time of Contect Switch.
+ *
+ * Special handling for r25 if used for caching Task Pointer.
+ * Kernel simply skips saving it since it will be loaded with
+ * incoming task pointer anyways
*-------------------------------------------------------------*/
.macro SAVE_CALLEE_SAVED_KERNEL
- st.a r13, [sp, -4]
- st.a r14, [sp, -4]
- st.a r15, [sp, -4]
- st.a r16, [sp, -4]
- st.a r17, [sp, -4]
- st.a r18, [sp, -4]
- st.a r19, [sp, -4]
- st.a r20, [sp, -4]
- st.a r21, [sp, -4]
- st.a r22, [sp, -4]
- st.a r23, [sp, -4]
- st.a r24, [sp, -4]
+
+ SAVE_R13_TO_R24
+
#ifdef CONFIG_ARC_CURR_IN_REG
sub sp, sp, 4
#else
- st.a r25, [sp, -4]
+ PUSH r25
#endif
.endm
/*--------------------------------------------------------------
- * RESTORE_CALLEE_SAVED_KERNEL:
- * Loads callee (non scratch) Reg File by popping from Kernel mode stack.
- * This is reverse of SAVE_CALLEE_SAVED,
- *
- * NOTE:
- * Ideally this shd only be called in switch_to for loading
- * switched-IN task's CALLEE Reg File.
- * For all other cases RESTORE_CALLEE_SAVED_FAST must be used
- * which simply pops the stack w/o touching regs.
+ * Opposite of SAVE_CALLEE_SAVED_KERNEL
*-------------------------------------------------------------*/
.macro RESTORE_CALLEE_SAVED_KERNEL
#ifdef CONFIG_ARC_CURR_IN_REG
add sp, sp, 4 /* skip usual r25 placeholder */
#else
- ld.ab r25, [sp, 4]
+ POP r25
#endif
- ld.ab r24, [sp, 4]
- ld.ab r23, [sp, 4]
- ld.ab r22, [sp, 4]
- ld.ab r21, [sp, 4]
- ld.ab r20, [sp, 4]
- ld.ab r19, [sp, 4]
- ld.ab r18, [sp, 4]
- ld.ab r17, [sp, 4]
- ld.ab r16, [sp, 4]
- ld.ab r15, [sp, 4]
- ld.ab r14, [sp, 4]
- ld.ab r13, [sp, 4]
-
+ RESTORE_R24_TO_R13
.endm
/*--------------------------------------------------------------
- * RESTORE_CALLEE_SAVED_USER:
- * This is called after do_signal where tracer might have changed callee regs
- * thus we need to restore the reg file.
- * Special case handling is required for r25 in case it is used by kernel
- * for caching task ptr. Ptrace would have modified on-kernel-stack value of
- * r25, which needs to be shoved back into task->thread.user_r25 where from
- * Low level exception/ISR return code will retrieve to populate with rest of
- * callee reg-file.
+ * Opposite of SAVE_CALLEE_SAVED_USER
+ *
+ * ptrace tracer or unaligned-access fixup might have changed a user mode
+ * callee reg which is saved back to usual r25 storage location
*-------------------------------------------------------------*/
.macro RESTORE_CALLEE_SAVED_USER
@@ -201,21 +206,9 @@
ld.ab r12, [sp, 4]
st r12, [r25, TASK_THREAD + THREAD_USER_R25]
#else
- ld.ab r25, [sp, 4]
+ POP r25
#endif
-
- ld.ab r24, [sp, 4]
- ld.ab r23, [sp, 4]
- ld.ab r22, [sp, 4]
- ld.ab r21, [sp, 4]
- ld.ab r20, [sp, 4]
- ld.ab r19, [sp, 4]
- ld.ab r18, [sp, 4]
- ld.ab r17, [sp, 4]
- ld.ab r16, [sp, 4]
- ld.ab r15, [sp, 4]
- ld.ab r14, [sp, 4]
- ld.ab r13, [sp, 4]
+ RESTORE_R24_TO_R13
.endm
/*--------------------------------------------------------------
@@ -357,7 +350,7 @@
* @reg [OUT] &thread_info of "current"
*/
.macro GET_CURR_THR_INFO_FROM_SP reg
- and \reg, sp, ~(THREAD_SIZE - 1)
+ bic \reg, sp, (THREAD_SIZE - 1)
.endm
/*
@@ -409,21 +402,16 @@
/* Restore r9 used to code the early prologue */
EXCPN_PROLOG_RESTORE_REG r9
- SAVE_CALLER_SAVED
- st.a r26, [sp, -4] /* gp */
- st.a fp, [sp, -4]
- st.a blink, [sp, -4]
- lr r9, [eret]
- st.a r9, [sp, -4]
- lr r9, [erstatus]
- st.a r9, [sp, -4]
- st.a lp_count, [sp, -4]
- lr r9, [lp_end]
- st.a r9, [sp, -4]
- lr r9, [lp_start]
- st.a r9, [sp, -4]
- lr r9, [erbta]
- st.a r9, [sp, -4]
+ SAVE_R0_TO_R12
+ PUSH gp
+ PUSH fp
+ PUSH blink
+ PUSHAX eret
+ PUSHAX erstatus
+ PUSH lp_count
+ PUSHAX lp_end
+ PUSHAX lp_start
+ PUSHAX erbta
.endm
/*--------------------------------------------------------------
@@ -463,22 +451,19 @@
* by hardware and that is not good.
*-------------------------------------------------------------*/
.macro RESTORE_ALL_SYS
- ld.ab r9, [sp, 4]
- sr r9, [erbta]
- ld.ab r9, [sp, 4]
- sr r9, [lp_start]
- ld.ab r9, [sp, 4]
- sr r9, [lp_end]
- ld.ab r9, [sp, 4]
- mov lp_count, r9
- ld.ab r9, [sp, 4]
- sr r9, [erstatus]
- ld.ab r9, [sp, 4]
- sr r9, [eret]
- ld.ab blink, [sp, 4]
- ld.ab fp, [sp, 4]
- ld.ab r26, [sp, 4] /* gp */
- RESTORE_CALLER_SAVED
+ POPAX erbta
+ POPAX lp_start
+ POPAX lp_end
+
+ POP r9
+ mov lp_count, r9 ;LD to lp_count is not allowed
+
+ POPAX erstatus
+ POPAX eret
+ POP blink
+ POP fp
+ POP gp
+ RESTORE_R12_TO_R0
ld sp, [sp] /* restore original sp */
/* orig_r0 and orig_r8 skipped automatically */
@@ -490,9 +475,7 @@
*-------------------------------------------------------------*/
.macro SAVE_ALL_INT1
- /* restore original r9 , saved in int1_saved_reg
- * It will be saved on stack in macro: SAVE_CALLER_SAVED
- */
+ /* restore original r9 to be saved as part of reg-file */
#ifdef CONFIG_SMP
lr r9, [ARC_REG_SCRATCH_DATA0]
#else
@@ -502,20 +485,17 @@
/* now we are ready to save the remaining context :) */
st orig_r8_IS_IRQ1, [sp, 8] /* Event Type */
st 0, [sp, 4] /* orig_r0 , N/A for IRQ */
- SAVE_CALLER_SAVED
- st.a r26, [sp, -4] /* gp */
- st.a fp, [sp, -4]
- st.a blink, [sp, -4]
- st.a ilink1, [sp, -4]
- lr r9, [status32_l1]
- st.a r9, [sp, -4]
- st.a lp_count, [sp, -4]
- lr r9, [lp_end]
- st.a r9, [sp, -4]
- lr r9, [lp_start]
- st.a r9, [sp, -4]
- lr r9, [bta_l1]
- st.a r9, [sp, -4]
+
+ SAVE_R0_TO_R12
+ PUSH gp
+ PUSH fp
+ PUSH blink
+ PUSH ilink1
+ PUSHAX status32_l1
+ PUSH lp_count
+ PUSHAX lp_end
+ PUSHAX lp_start
+ PUSHAX bta_l1
.endm
.macro SAVE_ALL_INT2
@@ -530,20 +510,17 @@
/* now we are ready to save the remaining context :) */
st orig_r8_IS_IRQ2, [sp, 8] /* Event Type */
st 0, [sp, 4] /* orig_r0 , N/A for IRQ */
- SAVE_CALLER_SAVED
- st.a r26, [sp, -4] /* gp */
- st.a fp, [sp, -4]
- st.a blink, [sp, -4]
- st.a ilink2, [sp, -4]
- lr r9, [status32_l2]
- st.a r9, [sp, -4]
- st.a lp_count, [sp, -4]
- lr r9, [lp_end]
- st.a r9, [sp, -4]
- lr r9, [lp_start]
- st.a r9, [sp, -4]
- lr r9, [bta_l2]
- st.a r9, [sp, -4]
+
+ SAVE_R0_TO_R12
+ PUSH gp
+ PUSH fp
+ PUSH blink
+ PUSH ilink2
+ PUSHAX status32_l2
+ PUSH lp_count
+ PUSHAX lp_end
+ PUSHAX lp_start
+ PUSHAX bta_l2
.endm
/*--------------------------------------------------------------
@@ -557,48 +534,41 @@
*-------------------------------------------------------------*/
.macro RESTORE_ALL_INT1
- ld.ab r9, [sp, 4] /* Actual reg file */
- sr r9, [bta_l1]
- ld.ab r9, [sp, 4]
- sr r9, [lp_start]
- ld.ab r9, [sp, 4]
- sr r9, [lp_end]
- ld.ab r9, [sp, 4]
- mov lp_count, r9
- ld.ab r9, [sp, 4]
- sr r9, [status32_l1]
- ld.ab r9, [sp, 4]
- mov ilink1, r9
- ld.ab blink, [sp, 4]
- ld.ab fp, [sp, 4]
- ld.ab r26, [sp, 4] /* gp */
- RESTORE_CALLER_SAVED
+ POPAX bta_l1
+ POPAX lp_start
+ POPAX lp_end
+
+ POP r9
+ mov lp_count, r9 ;LD to lp_count is not allowed
+
+ POPAX status32_l1
+ POP ilink1
+ POP blink
+ POP fp
+ POP gp
+ RESTORE_R12_TO_R0
ld sp, [sp] /* restore original sp */
/* orig_r0 and orig_r8 skipped automatically */
.endm
.macro RESTORE_ALL_INT2
- ld.ab r9, [sp, 4]
- sr r9, [bta_l2]
- ld.ab r9, [sp, 4]
- sr r9, [lp_start]
- ld.ab r9, [sp, 4]
- sr r9, [lp_end]
- ld.ab r9, [sp, 4]
- mov lp_count, r9
- ld.ab r9, [sp, 4]
- sr r9, [status32_l2]
- ld.ab r9, [sp, 4]
- mov ilink2, r9
- ld.ab blink, [sp, 4]
- ld.ab fp, [sp, 4]
- ld.ab r26, [sp, 4] /* gp */
- RESTORE_CALLER_SAVED
+ POPAX bta_l2
+ POPAX lp_start
+ POPAX lp_end
+
+ POP r9
+ mov lp_count, r9 ;LD to lp_count is not allowed
+
+ POPAX status32_l2
+ POP ilink2
+ POP blink
+ POP fp
+ POP gp
+ RESTORE_R12_TO_R0
ld sp, [sp] /* restore original sp */
/* orig_r0 and orig_r8 skipped automatically */
-
.endm
diff --git a/arch/arc/kernel/process.c b/arch/arc/kernel/process.c
index db868db..c6e22e0 100644
--- a/arch/arc/kernel/process.c
+++ b/arch/arc/kernel/process.c
@@ -73,6 +73,10 @@
* ~ ~
* | --to-- | (scratch Regs of user mode)
* | r0 |
+ * ------------------
+ * | SP |
+ * | orig_r0 |
+ * | orig_r8 |
* ------------------ <===== END of PAGE
*/
int copy_thread(unsigned long clone_flags,