[PATCH v2 16/20] ARC: entry: Add more common chores to EXCEPTION_PROLOGUE

Vineet Gupta
2023-08-20T02:36:05Z

THe high level structure of most ARC exception handlers is
1. save regfile with EXCEPTION_PROLOGUE
2. setup r0: EFA (not part of pt_regs)
3. setup r1: pointer to pt_regs (SP)
4. drop down to pure kernel mode (from exception)
5. call the Linux "C" handler

Remove the boiler plate code by moving #2, #3, #4 into #1.

The exceptions to most exceptions are syscall Trap and Machine check
which don't do some of above for various reasons, so call a newly
introduced variant EXCEPTION_PROLOGUE_KEEP_AE (same as original
EXCEPTION_PROLOGUE)

Tested-by: Pavel Kozlov <Pavel.Kozlov@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@kernel.org>
---
arch/arc/include/asm/entry-arcv2.h | 12 +++++++++++-
arch/arc/include/asm/entry-compact.h | 12 +++++++++++-
arch/arc/kernel/entry-arcv2.S | 15 ---------------
arch/arc/kernel/entry-compact.S | 13 -------------
arch/arc/kernel/entry.S | 19 ++-----------------
5 files changed, 24 insertions(+), 47 deletions(-)

diff --git a/arch/arc/include/asm/entry-arcv2.h b/arch/arc/include/asm/entry-arcv2.h
index a38ed505b3de..11b48ab39154 100644
--- a/arch/arc/include/asm/entry-arcv2.h
+++ b/arch/arc/include/asm/entry-arcv2.h
@@ -75,7 +75,7 @@
.endm

/*------------------------------------------------------------------------*/
-.macro EXCEPTION_PROLOGUE
+.macro EXCEPTION_PROLOGUE_KEEP_AE

; Before jumping to Exception Vector, hardware micro-ops did following:
; 1. SP auto-switched to kernel mode stack
@@ -104,6 +104,16 @@
; OUTPUT: r10 has ECR expected by EV_Trap
.endm

+.macro EXCEPTION_PROLOGUE
+
+ EXCEPTION_PROLOGUE_KEEP_AE ; return ECR in r10
+
+ lr r0, [efa]
+ mov r1, sp
+
+ FAKE_RET_FROM_EXCPN ; clobbers r9
+.endm
+
/*------------------------------------------------------------------------
* This macro saves the registers manually which would normally be autosaved
* by hardware on taken interrupts. It is used by
diff --git a/arch/arc/include/asm/entry-compact.h b/arch/arc/include/asm/entry-compact.h
index 4e2ae82779ed..a0e760eb35a8 100644
--- a/arch/arc/include/asm/entry-compact.h
+++ b/arch/arc/include/asm/entry-compact.h
@@ -140,7 +140,7 @@
*
* After this it is safe to call the "C" handlers
*-------------------------------------------------------------*/
-.macro EXCEPTION_PROLOGUE
+.macro EXCEPTION_PROLOGUE_KEEP_AE

/* Need at least 1 reg to code the early exception prologue */
PROLOG_FREEUP_REG r9, @ex_saved_reg1
@@ -179,6 +179,16 @@
; OUTPUT: r10 has ECR expected by EV_Trap
.endm

+.macro EXCEPTION_PROLOGUE
+
+ EXCEPTION_PROLOGUE_KEEP_AE ; return ECR in r10
+
+ lr r0, [efa]
+ mov r1, sp
+
+ FAKE_RET_FROM_EXCPN ; clobbers r9
+.endm
+
/*--------------------------------------------------------------
* Restore all registers used by system call or Exceptions
* SP should always be pointing to the next free stack element
diff --git a/arch/arc/kernel/entry-arcv2.S b/arch/arc/kernel/entry-arcv2.S
index a7e6a2174187..2e49c81c8086 100644
--- a/arch/arc/kernel/entry-arcv2.S
+++ b/arch/arc/kernel/entry-arcv2.S
@@ -125,11 +125,6 @@ ENTRY(mem_service)

EXCEPTION_PROLOGUE

- lr r0, [efa]
- mov r1, sp
-
- FAKE_RET_FROM_EXCPN
-
bl do_memory_error
b ret_from_exception
END(mem_service)
@@ -138,11 +133,6 @@ ENTRY(EV_Misaligned)

EXCEPTION_PROLOGUE

- lr r0, [efa] ; Faulting Data address
- mov r1, sp
-
- FAKE_RET_FROM_EXCPN
-
SAVE_CALLEE_SAVED_USER
mov r2, sp ; callee_regs

@@ -163,11 +153,6 @@ ENTRY(EV_TLBProtV)

EXCEPTION_PROLOGUE

- lr r0, [efa] ; Faulting Data address
- mov r1, sp ; pt_regs
-
- FAKE_RET_FROM_EXCPN
-
mov blink, ret_from_exception
b do_page_fault

diff --git a/arch/arc/kernel/entry-compact.S b/arch/arc/kernel/entry-compact.S
index 77f0090554c5..774c03cc1d1a 100644
--- a/arch/arc/kernel/entry-compact.S
+++ b/arch/arc/kernel/entry-compact.S
@@ -256,16 +256,6 @@ ENTRY(EV_TLBProtV)

EXCEPTION_PROLOGUE ; ECR returned in r10

- lr r0, [efa] ; Faulting Data address (not part of pt_regs saved above)
-
- ; Exception auto-disables further Intr/exceptions.
- ; Re-enable them by pretending to return from exception
- ; (so rest of handler executes in pure K mode)
-
- FAKE_RET_FROM_EXCPN
-
- mov r1, sp ; Handle to pt_regs
-
;------ (5) Type of Protection Violation? ----------
;
; ProtV Hardware Exception is triggered for Access Faults of 2 types
@@ -301,9 +291,6 @@ END(EV_TLBProtV)
ENTRY(call_do_page_fault)

EXCEPTION_PROLOGUE
- lr r0, [efa] ; Faulting Data address
- mov r1, sp
- FAKE_RET_FROM_EXCPN

mov blink, ret_from_exception
b do_page_fault
diff --git a/arch/arc/kernel/entry.S b/arch/arc/kernel/entry.S
index 46582fbebcf2..089f6680518f 100644
--- a/arch/arc/kernel/entry.S
+++ b/arch/arc/kernel/entry.S
@@ -80,11 +80,6 @@ ENTRY(instr_service)

EXCEPTION_PROLOGUE

- lr r0, [efa]
- mov r1, sp
-
- FAKE_RET_FROM_EXCPN
-
bl do_insterror_or_kprobe
b ret_from_exception
END(instr_service)
@@ -95,7 +90,7 @@ END(instr_service)

ENTRY(EV_MachineCheck)

- EXCEPTION_PROLOGUE ; ECR returned in r10
+ EXCEPTION_PROLOGUE_KEEP_AE ; ECR returned in r10

lr r0, [efa]
mov r1, sp
@@ -128,11 +123,6 @@ ENTRY(EV_PrivilegeV)

EXCEPTION_PROLOGUE

- lr r0, [efa]
- mov r1, sp
-
- FAKE_RET_FROM_EXCPN
-
bl do_privilege_fault
b ret_from_exception
END(EV_PrivilegeV)
@@ -144,11 +134,6 @@ ENTRY(EV_Extension)

EXCEPTION_PROLOGUE

- lr r0, [efa]
- mov r1, sp
-
- FAKE_RET_FROM_EXCPN
-
bl do_extension_fault
b ret_from_exception
END(EV_Extension)
@@ -229,7 +214,7 @@ trap_with_param:

ENTRY(EV_Trap)

- EXCEPTION_PROLOGUE
+ EXCEPTION_PROLOGUE_KEEP_AE

lr r12, [efa]

--
2.34.1