[PATCH 06/10] xtensa: implement call0 ABI support in assembly
From: Max Filippov
Date: Tue Oct 19 2021 - 01:17:54 EST
Replace hardcoded register and opcode names with ABI-agnostic macros.
Add register save/restore code where necessary. Conditionalize windowed
only or call0 only code. Add stack initialization matching _switch_to
epilogue to copy_thread.
Signed-off-by: Max Filippov <jcmvbkbc@xxxxxxxxx>
---
arch/xtensa/boot/boot-redboot/bootstrap.S | 68 +++----
arch/xtensa/kernel/entry.S | 209 ++++++++++++++--------
arch/xtensa/kernel/head.S | 22 +--
arch/xtensa/kernel/mcount.S | 38 +++-
arch/xtensa/kernel/process.c | 27 ++-
5 files changed, 243 insertions(+), 121 deletions(-)
diff --git a/arch/xtensa/boot/boot-redboot/bootstrap.S b/arch/xtensa/boot/boot-redboot/bootstrap.S
index 48ba5a232d94..51e8f3b88e82 100644
--- a/arch/xtensa/boot/boot-redboot/bootstrap.S
+++ b/arch/xtensa/boot/boot-redboot/bootstrap.S
@@ -3,6 +3,7 @@
#include <asm/regs.h>
#include <asm/asmmacro.h>
#include <asm/cacheasm.h>
+#include <asm/processor.h>
/*
* RB-Data: RedBoot data/bss
* P: Boot-Parameters
@@ -36,7 +37,7 @@
.globl __start
/* this must be the first byte of the loader! */
__start:
- entry sp, 32 # we do not intend to return
+ abi_entry(32) # we do not intend to return
_call0 _start
__start_a0:
.align 4
@@ -62,10 +63,12 @@ _start:
wsr a4, windowstart
rsync
- movi a4, 0x00040000
+ movi a4, KERNEL_PS_WOE_MASK
wsr a4, ps
rsync
+KABI_C0 mov abi_saved0, abi_arg0
+
/* copy the loader to its address
* Note: The loader itself is a very small piece, so we assume we
* don't partially overlap. We also assume (even more important)
@@ -168,52 +171,52 @@ _reloc:
movi a3, __image_load
sub a4, a3, a4
- add a8, a0, a4
+ add abi_arg2, a0, a4
# a1 Stack
# a8(a4) Load address of the image
- movi a6, _image_start
- movi a10, _image_end
- movi a7, 0x1000000
- sub a11, a10, a6
- movi a9, complen
- s32i a11, a9, 0
+ movi abi_arg0, _image_start
+ movi abi_arg4, _image_end
+ movi abi_arg1, 0x1000000
+ sub abi_tmp0, abi_arg4, abi_arg0
+ movi abi_arg3, complen
+ s32i abi_tmp0, abi_arg3, 0
movi a0, 0
- # a6 destination
- # a7 maximum size of destination
- # a8 source
- # a9 ptr to length
+ # abi_arg0 destination
+ # abi_arg1 maximum size of destination
+ # abi_arg2 source
+ # abi_arg3 ptr to length
.extern gunzip
- movi a4, gunzip
- beqz a4, 1f
+ movi abi_tmp0, gunzip
+ beqz abi_tmp0, 1f
- callx4 a4
+ abi_callx abi_tmp0
j 2f
- # a6 destination start
- # a7 maximum size of destination
- # a8 source start
- # a9 ptr to length
- # a10 destination end
+ # abi_arg0 destination start
+ # abi_arg1 maximum size of destination
+ # abi_arg2 source start
+ # abi_arg3 ptr to length
+ # abi_arg4 destination end
1:
- l32i a9, a8, 0
- l32i a11, a8, 4
- s32i a9, a6, 0
- s32i a11, a6, 4
- l32i a9, a8, 8
- l32i a11, a8, 12
- s32i a9, a6, 8
- s32i a11, a6, 12
- addi a6, a6, 16
- addi a8, a8, 16
- blt a6, a10, 1b
+ l32i abi_tmp0, abi_arg2, 0
+ l32i abi_tmp1, abi_arg2, 4
+ s32i abi_tmp0, abi_arg0, 0
+ s32i abi_tmp1, abi_arg0, 4
+ l32i abi_tmp0, abi_arg2, 8
+ l32i abi_tmp1, abi_arg2, 12
+ s32i abi_tmp0, abi_arg0, 8
+ s32i abi_tmp1, abi_arg0, 12
+ addi abi_arg0, abi_arg0, 16
+ addi abi_arg2, abi_arg2, 16
+ blt abi_arg0, abi_arg4, 1b
/* jump to the kernel */
@@ -230,6 +233,7 @@ _reloc:
# a2 Boot parameter list
+KABI_C0 mov abi_arg0, abi_saved0
movi a0, _image_start
jx a0
diff --git a/arch/xtensa/kernel/entry.S b/arch/xtensa/kernel/entry.S
index 647b162f959b..a144b467c3fd 100644
--- a/arch/xtensa/kernel/entry.S
+++ b/arch/xtensa/kernel/entry.S
@@ -158,6 +158,7 @@ _user_exception:
/* Rotate ws so that the current windowbase is at bit0. */
/* Assume ws = xxwww1yyyy. Rotate ws right, so that a2 = yyyyxxwww1 */
+#if defined(USER_SUPPORT_WINDOWED)
rsr a2, windowbase
rsr a3, windowstart
ssr a2
@@ -167,24 +168,33 @@ _user_exception:
src a2, a3, a2
srli a2, a2, 32-WSBITS
s32i a2, a1, PT_WMASK # needed for restoring registers
+#else
+ movi a2, 0
+ movi a3, 1
+ s32i a2, a1, PT_WINDOWBASE
+ s32i a3, a1, PT_WINDOWSTART
+ s32i a3, a1, PT_WMASK
+#endif
/* Save only live registers. */
- _bbsi.l a2, 1, 1f
+UABI_W _bbsi.l a2, 1, 1f
s32i a4, a1, PT_AREG4
s32i a5, a1, PT_AREG5
s32i a6, a1, PT_AREG6
s32i a7, a1, PT_AREG7
- _bbsi.l a2, 2, 1f
+UABI_W _bbsi.l a2, 2, 1f
s32i a8, a1, PT_AREG8
s32i a9, a1, PT_AREG9
s32i a10, a1, PT_AREG10
s32i a11, a1, PT_AREG11
- _bbsi.l a2, 3, 1f
+UABI_W _bbsi.l a2, 3, 1f
s32i a12, a1, PT_AREG12
s32i a13, a1, PT_AREG13
s32i a14, a1, PT_AREG14
s32i a15, a1, PT_AREG15
+
+#if defined(USER_SUPPORT_WINDOWED)
_bnei a2, 1, 1f # only one valid frame?
/* Only one valid frame, skip saving regs. */
@@ -239,7 +249,7 @@ _user_exception:
rsync
/* We are back to the original stack pointer (a1) */
-
+#endif
2: /* Now, jump to the common exception handler. */
j common_exception
@@ -295,6 +305,7 @@ _kernel_exception:
s32i a3, a1, PT_SAR
s32i a2, a1, PT_ICOUNTLEVEL
+#if defined(__XTENSA_WINDOWED_ABI__)
/* Rotate ws so that the current windowbase is at bit0. */
/* Assume ws = xxwww1yyyy. Rotate ws right, so that a2 = yyyyxxwww1 */
@@ -305,27 +316,28 @@ _kernel_exception:
src a2, a3, a2
srli a2, a2, 32-WSBITS
s32i a2, a1, PT_WMASK # needed for kernel_exception_exit
+#endif
/* Save only the live window-frame */
- _bbsi.l a2, 1, 1f
+KABI_W _bbsi.l a2, 1, 1f
s32i a4, a1, PT_AREG4
s32i a5, a1, PT_AREG5
s32i a6, a1, PT_AREG6
s32i a7, a1, PT_AREG7
- _bbsi.l a2, 2, 1f
+KABI_W _bbsi.l a2, 2, 1f
s32i a8, a1, PT_AREG8
s32i a9, a1, PT_AREG9
s32i a10, a1, PT_AREG10
s32i a11, a1, PT_AREG11
- _bbsi.l a2, 3, 1f
+KABI_W _bbsi.l a2, 3, 1f
s32i a12, a1, PT_AREG12
s32i a13, a1, PT_AREG13
s32i a14, a1, PT_AREG14
s32i a15, a1, PT_AREG15
+#ifdef __XTENSA_WINDOWED_ABI__
_bnei a2, 1, 1f
-
/* Copy spill slots of a0 and a1 to imitate movsp
* in order to keep exception stack continuous
*/
@@ -333,6 +345,7 @@ _kernel_exception:
l32i a0, a1, PT_SIZE + 4
s32e a3, a1, -16
s32e a0, a1, -12
+#endif
1:
l32i a0, a1, PT_AREG0 # restore saved a0
wsr a0, depc
@@ -419,16 +432,16 @@ common_exception:
movi a3, LOCKLEVEL
.Lexception:
- movi a0, PS_WOE_MASK
- or a3, a3, a0
+KABI_W movi a0, PS_WOE_MASK
+KABI_W or a3, a3, a0
#else
addi a2, a2, -EXCCAUSE_LEVEL1_INTERRUPT
movi a0, LOCKLEVEL
extui a3, a3, PS_INTLEVEL_SHIFT, PS_INTLEVEL_WIDTH
# a3 = PS.INTLEVEL
moveqz a3, a0, a2 # a3 = LOCKLEVEL iff interrupt
- movi a2, PS_WOE_MASK
- or a3, a3, a2
+KABI_W movi a2, PS_WOE_MASK
+KABI_W or a3, a3, a2
rsr a2, exccause
#endif
@@ -461,14 +474,14 @@ common_exception:
*/
rsr a4, excsave1
- mov a6, a1 # pass stack frame
- mov a7, a2 # pass EXCCAUSE
addx4 a4, a2, a4
l32i a4, a4, EXC_TABLE_DEFAULT # load handler
+ mov abi_arg1, a2 # pass EXCCAUSE
+ mov abi_arg0, a1 # pass stack frame
/* Call the second-level handler */
- callx4 a4
+ abi_callx a4
/* Jump here for exception exit */
.global common_exception_return
@@ -482,15 +495,15 @@ common_exception_return:
1:
irq_save a2, a3
#ifdef CONFIG_TRACE_IRQFLAGS
- call4 trace_hardirqs_off
+ abi_call trace_hardirqs_off
#endif
/* Jump if we are returning from kernel exceptions. */
- l32i a3, a1, PT_PS
+ l32i abi_saved1, a1, PT_PS
GET_THREAD_INFO(a2, a1)
l32i a4, a2, TI_FLAGS
- _bbci.l a3, PS_UM_BIT, 6f
+ _bbci.l abi_saved1, PS_UM_BIT, 6f
/* Specific to a user exception exit:
* We need to check some flags for signal handling and rescheduling,
@@ -509,20 +522,20 @@ common_exception_return:
/* Call do_signal() */
#ifdef CONFIG_TRACE_IRQFLAGS
- call4 trace_hardirqs_on
+ abi_call trace_hardirqs_on
#endif
rsil a2, 0
- mov a6, a1
- call4 do_notify_resume # int do_notify_resume(struct pt_regs*)
+ mov abi_arg0, a1
+ abi_call do_notify_resume # int do_notify_resume(struct pt_regs*)
j 1b
3: /* Reschedule */
#ifdef CONFIG_TRACE_IRQFLAGS
- call4 trace_hardirqs_on
+ abi_call trace_hardirqs_on
#endif
rsil a2, 0
- call4 schedule # void schedule (void)
+ abi_call schedule # void schedule (void)
j 1b
#ifdef CONFIG_PREEMPTION
@@ -533,33 +546,33 @@ common_exception_return:
l32i a4, a2, TI_PRE_COUNT
bnez a4, 4f
- call4 preempt_schedule_irq
+ abi_call preempt_schedule_irq
j 4f
#endif
#if XTENSA_FAKE_NMI
.LNMIexit:
- l32i a3, a1, PT_PS
- _bbci.l a3, PS_UM_BIT, 4f
+ l32i abi_saved1, a1, PT_PS
+ _bbci.l abi_saved1, PS_UM_BIT, 4f
#endif
5:
#ifdef CONFIG_HAVE_HW_BREAKPOINT
_bbci.l a4, TIF_DB_DISABLED, 7f
- call4 restore_dbreak
+ abi_call restore_dbreak
7:
#endif
#ifdef CONFIG_DEBUG_TLB_SANITY
l32i a4, a1, PT_DEPC
bgeui a4, VALID_DOUBLE_EXCEPTION_ADDRESS, 4f
- call4 check_tlb_sanity
+ abi_call check_tlb_sanity
#endif
6:
4:
#ifdef CONFIG_TRACE_IRQFLAGS
- extui a4, a3, PS_INTLEVEL_SHIFT, PS_INTLEVEL_WIDTH
+ extui a4, abi_saved1, PS_INTLEVEL_SHIFT, PS_INTLEVEL_WIDTH
bgei a4, LOCKLEVEL, 1f
- call4 trace_hardirqs_on
+ abi_call trace_hardirqs_on
1:
#endif
/* Restore optional registers. */
@@ -572,14 +585,15 @@ common_exception_return:
l32i a2, a1, PT_SCOMPARE1
wsr a2, scompare1
#endif
- wsr a3, ps /* disable interrupts */
+ wsr abi_saved1, ps /* disable interrupts */
- _bbci.l a3, PS_UM_BIT, kernel_exception_exit
+ _bbci.l abi_saved1, PS_UM_BIT, kernel_exception_exit
user_exception_exit:
/* Restore the state of the task and return from the exception. */
+#if defined(USER_SUPPORT_WINDOWED)
/* Switch to the user thread WINDOWBASE. Save SP temporarily in DEPC */
l32i a2, a1, PT_WINDOWBASE
@@ -634,8 +648,10 @@ user_exception_exit:
* frame where we had loaded a2), or at least the lower 4 bits
* (if we have restored WSBITS-1 frames).
*/
-
2:
+#else
+ movi a2, 1
+#endif
#if XCHAL_HAVE_THREADPTR
l32i a3, a1, PT_THREADPTR
wur a3, threadptr
@@ -650,6 +666,7 @@ user_exception_exit:
kernel_exception_exit:
+#if defined(__XTENSA_WINDOWED_ABI__)
/* Check if we have to do a movsp.
*
* We only have to do a movsp if the previous window-frame has
@@ -702,6 +719,9 @@ kernel_exception_exit:
*
* Note: We expect a2 to hold PT_WMASK
*/
+#else
+ movi a2, 1
+#endif
common_exception_exit:
@@ -927,7 +947,7 @@ ENTRY(unrecoverable_exception)
wsr a1, windowbase
rsync
- movi a1, PS_WOE_MASK | LOCKLEVEL
+ movi a1, KERNEL_PS_WOE_MASK | LOCKLEVEL
wsr a1, ps
rsync
@@ -935,8 +955,8 @@ ENTRY(unrecoverable_exception)
movi a0, 0
addi a1, a1, PT_REGS_OFFSET
- movi a6, unrecoverable_text
- call4 panic
+ movi abi_arg0, unrecoverable_text
+ abi_call panic
1: j 1b
@@ -1403,12 +1423,12 @@ ENTRY(fast_syscall_spill_registers)
rsr a3, excsave1
l32i a1, a3, EXC_TABLE_KSTK
- movi a4, PS_WOE_MASK | LOCKLEVEL
+ movi a4, KERNEL_PS_WOE_MASK | LOCKLEVEL
wsr a4, ps
rsync
- movi a6, SIGSEGV
- call4 do_exit
+ movi abi_arg0, SIGSEGV
+ abi_call do_exit
/* shouldn't return, so panic */
@@ -1887,57 +1907,77 @@ ENDPROC(fast_store_prohibited)
ENTRY(system_call)
+#if defined(__XTENSA_WINDOWED_ABI__)
abi_entry_default
+#elif defined(__XTENSA_CALL0_ABI__)
+ abi_entry(12)
+
+ s32i a0, sp, 0
+ s32i abi_saved0, sp, 4
+ s32i abi_saved1, sp, 8
+ mov abi_saved0, a2
+#else
+#error Unsupported Xtensa ABI
+#endif
/* regs->syscall = regs->areg[2] */
- l32i a7, a2, PT_AREG2
- s32i a7, a2, PT_SYSCALL
+ l32i a7, abi_saved0, PT_AREG2
+ s32i a7, abi_saved0, PT_SYSCALL
GET_THREAD_INFO(a4, a1)
- l32i a3, a4, TI_FLAGS
+ l32i abi_saved1, a4, TI_FLAGS
movi a4, _TIF_WORK_MASK
- and a3, a3, a4
- beqz a3, 1f
+ and abi_saved1, abi_saved1, a4
+ beqz abi_saved1, 1f
- mov a6, a2
- call4 do_syscall_trace_enter
- beqz a6, .Lsyscall_exit
- l32i a7, a2, PT_SYSCALL
+ mov abi_arg0, abi_saved0
+ abi_call do_syscall_trace_enter
+ beqz abi_rv, .Lsyscall_exit
+ l32i a7, abi_saved0, PT_SYSCALL
1:
/* syscall = sys_call_table[syscall_nr] */
movi a4, sys_call_table
movi a5, __NR_syscalls
- movi a6, -ENOSYS
+ movi abi_rv, -ENOSYS
bgeu a7, a5, 1f
addx4 a4, a7, a4
- l32i a4, a4, 0
+ l32i abi_tmp0, a4, 0
/* Load args: arg0 - arg5 are passed via regs. */
- l32i a6, a2, PT_AREG6
- l32i a7, a2, PT_AREG3
- l32i a8, a2, PT_AREG4
- l32i a9, a2, PT_AREG5
- l32i a10, a2, PT_AREG8
- l32i a11, a2, PT_AREG9
+ l32i abi_arg0, abi_saved0, PT_AREG6
+ l32i abi_arg1, abi_saved0, PT_AREG3
+ l32i abi_arg2, abi_saved0, PT_AREG4
+ l32i abi_arg3, abi_saved0, PT_AREG5
+ l32i abi_arg4, abi_saved0, PT_AREG8
+ l32i abi_arg5, abi_saved0, PT_AREG9
- callx4 a4
+ abi_callx abi_tmp0
1: /* regs->areg[2] = return_value */
- s32i a6, a2, PT_AREG2
- bnez a3, 1f
+ s32i abi_rv, abi_saved0, PT_AREG2
+ bnez abi_saved1, 1f
.Lsyscall_exit:
+#if defined(__XTENSA_WINDOWED_ABI__)
abi_ret_default
+#elif defined(__XTENSA_CALL0_ABI__)
+ l32i a0, sp, 0
+ l32i abi_saved0, sp, 4
+ l32i abi_saved1, sp, 8
+ abi_ret(12)
+#else
+#error Unsupported Xtensa ABI
+#endif
1:
- mov a6, a2
- call4 do_syscall_trace_leave
- abi_ret_default
+ mov abi_arg0, abi_saved0
+ abi_call do_syscall_trace_leave
+ j .Lsyscall_exit
ENDPROC(system_call)
@@ -1988,8 +2028,18 @@ ENDPROC(system_call)
ENTRY(_switch_to)
+#if defined(__XTENSA_WINDOWED_ABI__)
abi_entry(XTENSA_SPILL_STACK_RESERVE)
+#elif defined(__XTENSA_CALL0_ABI__)
+ abi_entry(16)
+ s32i a12, sp, 0
+ s32i a13, sp, 4
+ s32i a14, sp, 8
+ s32i a15, sp, 12
+#else
+#error Unsupported Xtensa ABI
+#endif
mov a11, a3 # and 'next' (a3)
l32i a4, a2, TASK_THREAD_INFO
@@ -2033,7 +2083,9 @@ ENTRY(_switch_to)
/* Flush register file. */
+#if defined(__XTENSA_WINDOWED_ABI__)
spill_registers_kernel
+#endif
/* Set kernel stack (and leave critical section)
* Note: It's save to set it here. The stack will not be overwritten
@@ -2055,34 +2107,43 @@ ENTRY(_switch_to)
wsr a14, ps
rsync
+#if defined(__XTENSA_WINDOWED_ABI__)
abi_ret(XTENSA_SPILL_STACK_RESERVE)
+#elif defined(__XTENSA_CALL0_ABI__)
+ l32i a12, sp, 0
+ l32i a13, sp, 4
+ l32i a14, sp, 8
+ l32i a15, sp, 12
+ abi_ret(16)
+#else
+#error Unsupported Xtensa ABI
+#endif
ENDPROC(_switch_to)
ENTRY(ret_from_fork)
/* void schedule_tail (struct task_struct *prev)
- * Note: prev is still in a6 (return value from fake call4 frame)
+ * Note: prev is still in abi_arg0 (return value from fake call frame)
*/
- call4 schedule_tail
-
- mov a6, a1
- call4 do_syscall_trace_leave
+ abi_call schedule_tail
- j common_exception_return
+ mov abi_arg0, a1
+ abi_call do_syscall_trace_leave
+ j common_exception_return
ENDPROC(ret_from_fork)
/*
* Kernel thread creation helper
- * On entry, set up by copy_thread: a2 = thread_fn, a3 = thread_fn arg
- * left from _switch_to: a6 = prev
+ * On entry, set up by copy_thread: abi_saved0 = thread_fn,
+ * abi_saved1 = thread_fn arg. Left from _switch_to: abi_arg0 = prev
*/
ENTRY(ret_from_kernel_thread)
- call4 schedule_tail
- mov a6, a3
- callx4 a2
- j common_exception_return
+ abi_call schedule_tail
+ mov abi_arg0, abi_saved1
+ abi_callx abi_saved0
+ j common_exception_return
ENDPROC(ret_from_kernel_thread)
diff --git a/arch/xtensa/kernel/head.S b/arch/xtensa/kernel/head.S
index b9b81e76beea..8972d64e0b86 100644
--- a/arch/xtensa/kernel/head.S
+++ b/arch/xtensa/kernel/head.S
@@ -15,6 +15,7 @@
* Kevin Chea
*/
+#include <asm/asmmacro.h>
#include <asm/processor.h>
#include <asm/page.h>
#include <asm/cacheasm.h>
@@ -193,9 +194,10 @@ ENTRY(_startup)
movi a1, start_info
l32i a1, a1, 0
- movi a2, PS_WOE_MASK | LOCKLEVEL
- # WOE=1, INTLEVEL=LOCKLEVEL, UM=0
- wsr a2, ps # (enable reg-windows; progmode stack)
+ /* Disable interrupts. */
+ /* Enable window exceptions if kernel is built with windowed ABI. */
+ movi a2, KERNEL_PS_WOE_MASK | LOCKLEVEL
+ wsr a2, ps
rsync
#ifdef CONFIG_SMP
@@ -267,13 +269,13 @@ ENTRY(_startup)
l32i a1, a1, 0
#endif
- movi a6, 0
- xsr a6, excsave1
+ movi abi_arg0, 0
+ xsr abi_arg0, excsave1
/* init_arch kick-starts the linux kernel */
- call4 init_arch
- call4 start_kernel
+ abi_call init_arch
+ abi_call start_kernel
should_never_return:
j should_never_return
@@ -297,10 +299,10 @@ should_never_return:
s32i a3, a2, 0
memw
- movi a6, 0
- wsr a6, excsave1
+ movi abi_arg0, 0
+ wsr abi_arg0, excsave1
- call4 secondary_start_kernel
+ abi_call secondary_start_kernel
j should_never_return
#endif /* CONFIG_SMP */
diff --git a/arch/xtensa/kernel/mcount.S b/arch/xtensa/kernel/mcount.S
index 5e4619f52858..51daaf4e0b82 100644
--- a/arch/xtensa/kernel/mcount.S
+++ b/arch/xtensa/kernel/mcount.S
@@ -17,11 +17,16 @@
/*
* Entry condition:
*
- * a2: a0 of the caller
+ * a2: a0 of the caller in windowed ABI
+ * a10: a0 of the caller in call0 ABI
+ *
+ * In call0 ABI the function _mcount is called with the special ABI:
+ * its argument is in a10 and all the usual argument registers (a2 - a7)
+ * must be preserved in addition to callee-saved a12 - a15.
*/
ENTRY(_mcount)
-
+#if defined(__XTENSA_WINDOWED_ABI__)
abi_entry_default
movi a4, ftrace_trace_function
@@ -42,7 +47,36 @@ ENTRY(_mcount)
callx4 a4
abi_ret_default
+#elif defined(__XTENSA_CALL0_ABI__)
+ abi_entry_default
+
+ movi a9, ftrace_trace_function
+ l32i a9, a9, 0
+ movi a11, ftrace_stub
+ bne a9, a11, 1f
+ abi_ret_default
+1: abi_entry(28)
+ s32i a0, sp, 0
+ s32i a2, sp, 4
+ s32i a3, sp, 8
+ s32i a4, sp, 12
+ s32i a5, sp, 16
+ s32i a6, sp, 20
+ s32i a7, sp, 24
+ addi a2, a10, -MCOUNT_INSN_SIZE
+ callx0 a9
+ l32i a0, sp, 0
+ l32i a2, sp, 4
+ l32i a3, sp, 8
+ l32i a4, sp, 12
+ l32i a5, sp, 16
+ l32i a6, sp, 20
+ l32i a7, sp, 24
+ abi_ret(28)
+#else
+#error Unsupported Xtensa ABI
+#endif
ENDPROC(_mcount)
ENTRY(ftrace_stub)
diff --git a/arch/xtensa/kernel/process.c b/arch/xtensa/kernel/process.c
index 060165340612..de6eb9ddea44 100644
--- a/arch/xtensa/kernel/process.c
+++ b/arch/xtensa/kernel/process.c
@@ -211,11 +211,18 @@ int copy_thread(unsigned long clone_flags, unsigned long usp_thread_fn,
struct thread_info *ti;
#endif
+#if defined(__XTENSA_WINDOWED_ABI__)
/* Create a call4 dummy-frame: a0 = 0, a1 = childregs. */
SPILL_SLOT(childregs, 1) = (unsigned long)childregs;
SPILL_SLOT(childregs, 0) = 0;
p->thread.sp = (unsigned long)childregs;
+#elif defined(__XTENSA_CALL0_ABI__)
+ /* Reserve 16 bytes for the _switch_to stack frame. */
+ p->thread.sp = (unsigned long)childregs - 16;
+#else
+#error Unsupported Xtensa ABI
+#endif
if (!(p->flags & (PF_KTHREAD | PF_IO_WORKER))) {
struct pt_regs *regs = current_pt_regs();
@@ -272,11 +279,25 @@ int copy_thread(unsigned long clone_flags, unsigned long usp_thread_fn,
p->thread.ra = MAKE_RA_FOR_CALL(
(unsigned long)ret_from_kernel_thread, 1);
- /* pass parameters to ret_from_kernel_thread:
- * a2 = thread_fn, a3 = thread_fn arg
+ /* pass parameters to ret_from_kernel_thread: */
+#if defined(__XTENSA_WINDOWED_ABI__)
+ /*
+ * a2 = thread_fn, a3 = thread_fn arg.
+ * Window underflow will load registers from the
+ * spill slots on the stack on return from _switch_to.
*/
- SPILL_SLOT(childregs, 3) = thread_fn_arg;
SPILL_SLOT(childregs, 2) = usp_thread_fn;
+ SPILL_SLOT(childregs, 3) = thread_fn_arg;
+#elif defined(__XTENSA_CALL0_ABI__)
+ /*
+ * a12 = thread_fn, a13 = thread_fn arg.
+ * _switch_to epilogue will load registers from the stack.
+ */
+ ((unsigned long *)p->thread.sp)[0] = usp_thread_fn;
+ ((unsigned long *)p->thread.sp)[1] = thread_fn_arg;
+#else
+#error Unsupported Xtensa ABI
+#endif
/* Childregs are only used when we're going to userspace
* in which case start_thread will set them up.
--
2.20.1