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From af5e43cd88d4b7d59260de6bdacbf715e2a7ff5d Mon Sep 17 00:00:00 2001
From: Waldemar Brodkorb <wbx@openadk.org>
Date: Fri, 16 Oct 2020 01:17:24 +0200
Subject: [PATCH] Revert "ARC: entry: fix potential EFA clobber when
TIF_SYSCALL_TRACE"
This reverts commit 01b636cbc4c39c7073c02c2f1dfbe8c36c11938f.
Signed-off-by: Waldemar Brodkorb <wbx@openadk.org>
---
arch/arc/kernel/entry.S | 16 +++++++++++-----
1 file changed, 11 insertions(+), 5 deletions(-)
diff --git a/arch/arc/kernel/entry.S b/arch/arc/kernel/entry.S
index 705a68208423..85d9ea4a0acc 100644
--- a/arch/arc/kernel/entry.S
+++ b/arch/arc/kernel/entry.S
@@ -156,6 +156,7 @@ END(EV_Extension)
tracesys:
; save EFA in case tracer wants the PC of traced task
; using ERET won't work since next-PC has already committed
+ lr r12, [efa]
GET_CURR_TASK_FIELD_PTR TASK_THREAD, r11
st r12, [r11, THREAD_FAULT_ADDR] ; thread.fault_address
@@ -198,9 +199,15 @@ tracesys_exit:
; Breakpoint TRAP
; ---------------------------------------------
trap_with_param:
- mov r0, r12 ; EFA in case ptracer/gdb wants stop_pc
+
+ ; stop_pc info by gdb needs this info
+ lr r0, [efa]
mov r1, sp
+ ; Now that we have read EFA, it is safe to do "fake" rtie
+ ; and get out of CPU exception mode
+ FAKE_RET_FROM_EXCPN
+
; Save callee regs in case gdb wants to have a look
; SP will grow up by size of CALLEE Reg-File
; NOTE: clobbers r12
@@ -227,10 +234,6 @@ ENTRY(EV_Trap)
EXCEPTION_PROLOGUE
- lr r12, [efa]
-
- FAKE_RET_FROM_EXCPN
-
;============ TRAP 1 :breakpoints
; Check ECR for trap with arg (PROLOGUE ensures r9 has ECR)
bmsk.f 0, r9, 7
@@ -238,6 +241,9 @@ ENTRY(EV_Trap)
;============ TRAP (no param): syscall top level
+ ; First return from Exception to pure K mode (Exception/IRQs renabled)
+ FAKE_RET_FROM_EXCPN
+
; If syscall tracing ongoing, invoke pre-post-hooks
GET_CURR_THR_INFO_FLAGS r10
btst r10, TIF_SYSCALL_TRACE
--
2.11.0
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