From 450e5b6f654b52bd7495e84cd46dd37d7e184415 Mon Sep 17 00:00:00 2001
From: Vineet Gupta <vgupta@synopsys.com>
Date: Tue, 14 May 2019 14:22:47 -0700
Subject: ARC: mm: do_page_fault refactor #1: remove label @good_area

Invert the condition for stack expansion.
No functional change

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
---
 arch/arc/mm/fault.c | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

(limited to 'arch/arc')

diff --git a/arch/arc/mm/fault.c b/arch/arc/mm/fault.c
index 8cca03480bb2..be8ea91fcc8b 100644
--- a/arch/arc/mm/fault.c
+++ b/arch/arc/mm/fault.c
@@ -97,21 +97,19 @@ void do_page_fault(unsigned long address, struct pt_regs *regs)
 		flags |= FAULT_FLAG_USER;
 retry:
 	down_read(&mm->mmap_sem);
+
 	vma = find_vma(mm, address);
 	if (!vma)
 		goto bad_area;
-	if (vma->vm_start <= address)
-		goto good_area;
-	if (!(vma->vm_flags & VM_GROWSDOWN))
-		goto bad_area;
-	if (expand_stack(vma, address))
-		goto bad_area;
+	if (unlikely(address < vma->vm_start)) {
+		if (!(vma->vm_flags & VM_GROWSDOWN) || expand_stack(vma, address))
+			goto bad_area;
+	}
 
 	/*
 	 * Ok, we have a good vm_area for this memory access, so
 	 * we can handle it..
 	 */
-good_area:
 	si_code = SEGV_ACCERR;
 
 	/* Handle protection violation, execute on heap or stack */
-- 
cgit v1.2.3-58-ga151


From 13e2cc1240eb14d1a08b2c32f88b25bf20210ebc Mon Sep 17 00:00:00 2001
From: Vineet Gupta <vgupta@synopsys.com>
Date: Tue, 14 May 2019 16:07:24 -0700
Subject: ARC: mm: do_page_fault refactor #2: remove short lived variable

Compiler will do this anyways, still..

No functional change.

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
---
 arch/arc/mm/fault.c | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

(limited to 'arch/arc')

diff --git a/arch/arc/mm/fault.c b/arch/arc/mm/fault.c
index be8ea91fcc8b..a3a292c58e50 100644
--- a/arch/arc/mm/fault.c
+++ b/arch/arc/mm/fault.c
@@ -64,23 +64,18 @@ void do_page_fault(unsigned long address, struct pt_regs *regs)
 	struct task_struct *tsk = current;
 	struct mm_struct *mm = tsk->mm;
 	int si_code = SEGV_MAPERR;
-	int ret;
 	vm_fault_t fault;
 	int write = regs->ecr_cause & ECR_C_PROTV_STORE;  /* ST/EX */
 	unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
 
 	/*
-	 * We fault-in kernel-space virtual memory on-demand. The
-	 * 'reference' page table is init_mm.pgd.
-	 *
 	 * NOTE! We MUST NOT take any locks for this case. We may
 	 * be in an interrupt or a critical region, and should
 	 * only copy the information from the master page table,
 	 * nothing more.
 	 */
 	if (address >= VMALLOC_START && !user_mode(regs)) {
-		ret = handle_kernel_vaddr_fault(address);
-		if (unlikely(ret))
+		if (unlikely(handle_kernel_vaddr_fault(address)))
 			goto no_context;
 		else
 			return;
-- 
cgit v1.2.3-58-ga151


From 85c5e33763a731967ca59085ffe6e694f872d38e Mon Sep 17 00:00:00 2001
From: Vineet Gupta <vgupta@synopsys.com>
Date: Tue, 14 May 2019 14:25:54 -0700
Subject: ARC: mm: do_page_fault refactor #3: tidyup vma access permission code

The coding pattern to NOT intialize variables at declaration time but
rather near code which makes us eof them makes it much easier to grok
the overall logic, specially when the init is not simply 0 or 1

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
---
 arch/arc/mm/fault.c | 39 +++++++++++++++++++++------------------
 1 file changed, 21 insertions(+), 18 deletions(-)

(limited to 'arch/arc')

diff --git a/arch/arc/mm/fault.c b/arch/arc/mm/fault.c
index a3a292c58e50..8c7c81ce7f6a 100644
--- a/arch/arc/mm/fault.c
+++ b/arch/arc/mm/fault.c
@@ -64,9 +64,9 @@ void do_page_fault(unsigned long address, struct pt_regs *regs)
 	struct task_struct *tsk = current;
 	struct mm_struct *mm = tsk->mm;
 	int si_code = SEGV_MAPERR;
+	unsigned int write = 0, exec = 0, mask;
 	vm_fault_t fault;
-	int write = regs->ecr_cause & ECR_C_PROTV_STORE;  /* ST/EX */
-	unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
+	unsigned int flags;
 
 	/*
 	 * NOTE! We MUST NOT take any locks for this case. We may
@@ -88,8 +88,18 @@ void do_page_fault(unsigned long address, struct pt_regs *regs)
 	if (faulthandler_disabled() || !mm)
 		goto no_context;
 
+	if (regs->ecr_cause & ECR_C_PROTV_STORE)	/* ST/EX */
+		write = 1;
+	else if ((regs->ecr_vec == ECR_V_PROTV) &&
+	         (regs->ecr_cause == ECR_C_PROTV_INST_FETCH))
+		exec = 1;
+
+	flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
 	if (user_mode(regs))
 		flags |= FAULT_FLAG_USER;
+	if (write)
+		flags |= FAULT_FLAG_WRITE;
+
 retry:
 	down_read(&mm->mmap_sem);
 
@@ -102,24 +112,17 @@ retry:
 	}
 
 	/*
-	 * Ok, we have a good vm_area for this memory access, so
-	 * we can handle it..
+	 * vm_area is good, now check permissions for this memory access
 	 */
-	si_code = SEGV_ACCERR;
-
-	/* Handle protection violation, execute on heap or stack */
-
-	if ((regs->ecr_vec == ECR_V_PROTV) &&
-	    (regs->ecr_cause == ECR_C_PROTV_INST_FETCH))
+	mask = VM_READ;
+	if (write)
+		mask = VM_WRITE;
+	if (exec)
+		mask = VM_EXEC;
+
+	if (!(vma->vm_flags & mask)) {
+		si_code = SEGV_ACCERR;
 		goto bad_area;
-
-	if (write) {
-		if (!(vma->vm_flags & VM_WRITE))
-			goto bad_area;
-		flags |= FAULT_FLAG_WRITE;
-	} else {
-		if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
-			goto bad_area;
 	}
 
 	/*
-- 
cgit v1.2.3-58-ga151


From 02c88d142ea6e64b0f81dcf3687a889d8a3556ba Mon Sep 17 00:00:00 2001
From: Vineet Gupta <vgupta@synopsys.com>
Date: Tue, 14 May 2019 14:35:45 -0700
Subject: ARC: mm: do_page_fault refactor #4: consolidate retry related logic

stats update code can now elide "retry" check and additional level of
indentation since all retry handling is done ahead of it already

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
---
 arch/arc/mm/fault.c | 60 +++++++++++++++++++++++++++--------------------------
 1 file changed, 31 insertions(+), 29 deletions(-)

(limited to 'arch/arc')

diff --git a/arch/arc/mm/fault.c b/arch/arc/mm/fault.c
index 8c7c81ce7f6a..4597b4886edd 100644
--- a/arch/arc/mm/fault.c
+++ b/arch/arc/mm/fault.c
@@ -65,8 +65,8 @@ void do_page_fault(unsigned long address, struct pt_regs *regs)
 	struct mm_struct *mm = tsk->mm;
 	int si_code = SEGV_MAPERR;
 	unsigned int write = 0, exec = 0, mask;
-	vm_fault_t fault;
-	unsigned int flags;
+	vm_fault_t fault;			/* handle_mm_fault() output */
+	unsigned int flags;			/* handle_mm_fault() input */
 
 	/*
 	 * NOTE! We MUST NOT take any locks for this case. We may
@@ -125,49 +125,51 @@ retry:
 		goto bad_area;
 	}
 
-	/*
-	 * If for any reason at all we couldn't handle the fault,
-	 * make sure we exit gracefully rather than endlessly redo
-	 * the fault.
-	 */
 	fault = handle_mm_fault(vma, address, flags);
 
-	if (fatal_signal_pending(current)) {
+	/*
+	 * Fault retry nuances
+	 */
+	if (unlikely(fault & VM_FAULT_RETRY)) {
 
 		/*
-		 * if fault retry, mmap_sem already relinquished by core mm
-		 * so OK to return to user mode (with signal handled first)
+		 * If fault needs to be retried, handle any pending signals
+		 * first (by returning to user mode).
+		 * mmap_sem already relinquished by core mm for RETRY case
 		 */
-		if (fault & VM_FAULT_RETRY) {
+		if (fatal_signal_pending(current)) {
 			if (!user_mode(regs))
 				goto no_context;
 			return;
 		}
+		/*
+		 * retry state machine
+		 */
+		if (flags & FAULT_FLAG_ALLOW_RETRY) {
+			flags &= ~FAULT_FLAG_ALLOW_RETRY;
+			flags |= FAULT_FLAG_TRIED;
+			goto retry;
+		}
 	}
 
+	/*
+	 * Major/minor page fault accounting
+	 * (in case of retry we only land here once)
+	 */
 	perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
 
 	if (likely(!(fault & VM_FAULT_ERROR))) {
-		if (flags & FAULT_FLAG_ALLOW_RETRY) {
-			/* To avoid updating stats twice for retry case */
-			if (fault & VM_FAULT_MAJOR) {
-				tsk->maj_flt++;
-				perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1,
-					      regs, address);
-			} else {
-				tsk->min_flt++;
-				perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1,
-					      regs, address);
-			}
-
-			if (fault & VM_FAULT_RETRY) {
-				flags &= ~FAULT_FLAG_ALLOW_RETRY;
-				flags |= FAULT_FLAG_TRIED;
-				goto retry;
-			}
+		if (fault & VM_FAULT_MAJOR) {
+			tsk->maj_flt++;
+			perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1,
+				      regs, address);
+		} else {
+			tsk->min_flt++;
+			perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1,
+				      regs, address);
 		}
 
-		/* Fault Handled Gracefully */
+		/* Normal return path: fault Handled Gracefully */
 		up_read(&mm->mmap_sem);
 		return;
 	}
-- 
cgit v1.2.3-58-ga151


From d0542c7eacd5b507fa53570b610706df122a2f37 Mon Sep 17 00:00:00 2001
From: Vineet Gupta <vgupta@synopsys.com>
Date: Tue, 14 May 2019 14:45:44 -0700
Subject: ARC: mm: do_page_fault refactor #5: scoot no_context to end

This is different than the rest of signal handling stuff

No functional change

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
---
 arch/arc/mm/fault.c | 21 +++++++--------------
 1 file changed, 7 insertions(+), 14 deletions(-)

(limited to 'arch/arc')

diff --git a/arch/arc/mm/fault.c b/arch/arc/mm/fault.c
index 4597b4886edd..b107e45cce94 100644
--- a/arch/arc/mm/fault.c
+++ b/arch/arc/mm/fault.c
@@ -198,20 +198,6 @@ bad_area:
 		return;
 	}
 
-no_context:
-	/* Are we prepared to handle this kernel fault?
-	 *
-	 * (The kernel has valid exception-points in the source
-	 *  when it accesses user-memory. When it fails in one
-	 *  of those points, we find it in a table and do a jump
-	 *  to some fixup code that loads an appropriate error
-	 *  code)
-	 */
-	if (fixup_exception(regs))
-		return;
-
-	die("Oops", regs, address);
-
 out_of_memory:
 	up_read(&mm->mmap_sem);
 
@@ -230,4 +216,11 @@ do_sigbus:
 
 	tsk->thread.fault_address = address;
 	force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *)address, tsk);
+	return;
+
+no_context:
+	if (fixup_exception(regs))
+		return;
+
+	die("Oops", regs, address);
 }
-- 
cgit v1.2.3-58-ga151


From 98cb57ad70fb7c8a9c030d3e83fe66b546906e28 Mon Sep 17 00:00:00 2001
From: Vineet Gupta <vgupta@synopsys.com>
Date: Tue, 14 May 2019 15:10:45 -0700
Subject: ARC: mm: do_page_fault refactor #6: error handlers to use same
 pattern

 - up_read
 - if !user_mode
 - whatever error handling

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
---
 arch/arc/mm/fault.c | 21 ++++++++++-----------
 1 file changed, 10 insertions(+), 11 deletions(-)

(limited to 'arch/arc')

diff --git a/arch/arc/mm/fault.c b/arch/arc/mm/fault.c
index b107e45cce94..2672ce24d741 100644
--- a/arch/arc/mm/fault.c
+++ b/arch/arc/mm/fault.c
@@ -191,22 +191,21 @@ retry:
 bad_area:
 	up_read(&mm->mmap_sem);
 
-	/* User mode accesses just cause a SIGSEGV */
-	if (user_mode(regs)) {
-		tsk->thread.fault_address = address;
-		force_sig_fault(SIGSEGV, si_code, (void __user *)address, tsk);
-		return;
-	}
+	if (!user_mode(regs))
+		goto no_context;
+
+	tsk->thread.fault_address = address;
+	force_sig_fault(SIGSEGV, si_code, (void __user *)address, tsk);
+	return;
 
 out_of_memory:
 	up_read(&mm->mmap_sem);
 
-	if (user_mode(regs)) {
-		pagefault_out_of_memory();
-		return;
-	}
+	if (!user_mode(regs))
+		goto no_context;
 
-	goto no_context;
+	pagefault_out_of_memory();
+	return;
 
 do_sigbus:
 	up_read(&mm->mmap_sem);
-- 
cgit v1.2.3-58-ga151


From 5e91bf5ce9b8740076f5283f1ec3a5b023950920 Mon Sep 17 00:00:00 2001
From: Vineet Gupta <vgupta@synopsys.com>
Date: Tue, 14 May 2019 15:55:31 -0700
Subject: ARC: mm: do_page_fault refactor #7: fold the various error handling

 - single up_read() call vs. 4
 - so much easier on eyes

Technically it seems like @bad_area label moved up, but even in old
regime, it was a special case of delivering SIGSEGV unconditionally
which we now do as well, although with checks.

Also note that @fault needs to be initialized since we can land in
@bad_area (which reads it) without setting it up with return value of
handle_mm_fault() - failing to do so did bite us although as a side
effect of different patch: see [1]

[1]: http://lists.infradead.org/pipermail/linux-snps-arc/2019-May/005803.html

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
---
 arch/arc/mm/fault.c | 48 ++++++++++++++----------------------------------
 1 file changed, 14 insertions(+), 34 deletions(-)

(limited to 'arch/arc')

diff --git a/arch/arc/mm/fault.c b/arch/arc/mm/fault.c
index 2672ce24d741..6a78a2d776a9 100644
--- a/arch/arc/mm/fault.c
+++ b/arch/arc/mm/fault.c
@@ -63,9 +63,9 @@ void do_page_fault(unsigned long address, struct pt_regs *regs)
 	struct vm_area_struct *vma = NULL;
 	struct task_struct *tsk = current;
 	struct mm_struct *mm = tsk->mm;
-	int si_code = SEGV_MAPERR;
+	int sig, si_code = SEGV_MAPERR;
 	unsigned int write = 0, exec = 0, mask;
-	vm_fault_t fault;			/* handle_mm_fault() output */
+	vm_fault_t fault = VM_FAULT_SIGSEGV;	/* handle_mm_fault() output */
 	unsigned int flags;			/* handle_mm_fault() input */
 
 	/*
@@ -174,47 +174,27 @@ retry:
 		return;
 	}
 
-	if (fault & VM_FAULT_OOM)
-		goto out_of_memory;
-	else if (fault & VM_FAULT_SIGSEGV)
-		goto bad_area;
-	else if (fault & VM_FAULT_SIGBUS)
-		goto do_sigbus;
-
-	/* no man's land */
-	BUG();
-
-	/*
-	 * Something tried to access memory that isn't in our memory map..
-	 * Fix it, but check if it's kernel or user first..
-	 */
 bad_area:
 	up_read(&mm->mmap_sem);
 
 	if (!user_mode(regs))
 		goto no_context;
 
-	tsk->thread.fault_address = address;
-	force_sig_fault(SIGSEGV, si_code, (void __user *)address, tsk);
-	return;
-
-out_of_memory:
-	up_read(&mm->mmap_sem);
-
-	if (!user_mode(regs))
-		goto no_context;
-
-	pagefault_out_of_memory();
-	return;
-
-do_sigbus:
-	up_read(&mm->mmap_sem);
+	if (fault & VM_FAULT_OOM) {
+		pagefault_out_of_memory();
+		return;
+	}
 
-	if (!user_mode(regs))
-		goto no_context;
+	if (fault & VM_FAULT_SIGBUS) {
+		sig = SIGBUS;
+		si_code = BUS_ADRERR;
+	}
+	else {
+		sig = SIGSEGV;
+	}
 
 	tsk->thread.fault_address = address;
-	force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *)address, tsk);
+	force_sig_fault(sig, si_code, (void __user *)address, tsk);
 	return;
 
 no_context:
-- 
cgit v1.2.3-58-ga151


From 926150db8558dca59617c8786c3f91c239290ee1 Mon Sep 17 00:00:00 2001
From: Vineet Gupta <vgupta@synopsys.com>
Date: Tue, 14 May 2019 16:28:30 -0700
Subject: ARC: mm: do_page_fault refactor #8: release mmap_sem sooner

In case of successful page fault handling, this patch releases mmap_sem
before updating the perf stat event for major/minor faults. So even
though the contention reduction is NOT super high, it is still an
improvement.

There's an additional code size improvement as we only have 2 up_read()
calls now.

Note to myself:
--------------

1. Given the way it is done, we are forced to move @bad_area label earlier
   causing the various "goto bad_area" cases to hit perf stat code.

 - PERF_COUNT_SW_PAGE_FAULTS is NOW updated for access errors which is what
   arm/arm64 seem to be doing as well (with slightly different code)
 - PERF_COUNT_SW_PAGE_FAULTS_{MAJ,MIN} must NOT be updated for the
   error case which is guarded by now setting @fault initial value
   to VM_FAULT_ERROR which serves both cases when handle_mm_fault()
   returns error or is not called at all.

2. arm/arm64 use two homebrew fault flags VM_FAULT_BAD{MAP,MAPACCESS}
   which I was inclined to add too but seems not needed for ARC

 - given that we have everything is 1 function we can still use goto
 - we setup si_code at the right place (arm* do that in the end)
 - we init fault already to error value which guards entry into perf
   stats event update

Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
---
 arch/arc/mm/fault.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

(limited to 'arch/arc')

diff --git a/arch/arc/mm/fault.c b/arch/arc/mm/fault.c
index 6a78a2d776a9..e7df5ef3877a 100644
--- a/arch/arc/mm/fault.c
+++ b/arch/arc/mm/fault.c
@@ -152,6 +152,9 @@ retry:
 		}
 	}
 
+bad_area:
+	up_read(&mm->mmap_sem);
+
 	/*
 	 * Major/minor page fault accounting
 	 * (in case of retry we only land here once)
@@ -170,13 +173,9 @@ retry:
 		}
 
 		/* Normal return path: fault Handled Gracefully */
-		up_read(&mm->mmap_sem);
 		return;
 	}
 
-bad_area:
-	up_read(&mm->mmap_sem);
-
 	if (!user_mode(regs))
 		goto no_context;
 
-- 
cgit v1.2.3-58-ga151


From 45869eb0c0afd72bd5ab2437d4b00915697c044a Mon Sep 17 00:00:00 2001
From: Vineet Gupta <vgupta@synopsys.com>
Date: Tue, 9 Apr 2019 16:55:15 -0700
Subject: ARCv2: entry: comments about hardware auto-save on taken interrupts

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
---
 arch/arc/include/asm/entry-arcv2.h | 78 ++++++++++++++++++++++++++++++--------
 1 file changed, 62 insertions(+), 16 deletions(-)

(limited to 'arch/arc')

diff --git a/arch/arc/include/asm/entry-arcv2.h b/arch/arc/include/asm/entry-arcv2.h
index 225e7df2d8ed..1c3520d1fa42 100644
--- a/arch/arc/include/asm/entry-arcv2.h
+++ b/arch/arc/include/asm/entry-arcv2.h
@@ -7,15 +7,54 @@
 #include <asm/irqflags-arcv2.h>
 #include <asm/thread_info.h>	/* For THREAD_SIZE */
 
+/*
+ * Interrupt/Exception stack layout (pt_regs) for ARCv2
+ *   (End of struct aligned to end of page [unless nested])
+ *
+ *  INTERRUPT                          EXCEPTION
+ *
+ *    manual    ---------------------  manual
+ *              |      orig_r0      |
+ *              |      event/ECR    |
+ *              |      bta          |
+ *              |      user_r25     |
+ *              |      gp           |
+ *              |      fp           |
+ *              |      sp           |
+ *              |      r12          |
+ *              |      r30          |
+ *              |      r58          |
+ *              |      r59          |
+ *  hw autosave ---------------------
+ *    optional  |      r0           |
+ *              |      r1           |
+ *              ~                   ~
+ *              |      r9           |
+ *              |      r10          |
+ *              |      r11          |
+ *              |      blink        |
+ *              |      lpe          |
+ *              |      lps          |
+ *              |      lpc          |
+ *              |      ei base      |
+ *              |      ldi base     |
+ *              |      jli base     |
+ *              ---------------------
+ *  hw autosave |       pc / eret   |
+ *   mandatory  | stat32 / erstatus |
+ *              ---------------------
+ */
+
 /*------------------------------------------------------------------------*/
 .macro INTERRUPT_PROLOGUE	called_from
-
-	; Before jumping to Interrupt Vector, hardware micro-ops did following:
+	; (A) Before jumping to Interrupt Vector, hardware micro-ops did following:
 	;   1. SP auto-switched to kernel mode stack
-	;   2. STATUS32.Z flag set to U mode at time of interrupt (U:1, K:0)
-	;   3. Auto saved: r0-r11, blink, LPE,LPS,LPC, JLI,LDI,EI, PC, STAT32
+	;   2. STATUS32.Z flag set if in U mode at time of interrupt (U:1,K:0)
+	;   3. Auto save: (mandatory) Push PC and STAT32 on stack
+	;                 hardware does even if CONFIG_ARC_IRQ_NO_AUTOSAVE
+	;   4. Auto save: (optional) r0-r11, blink, LPE,LPS,LPC, JLI,LDI,EI
 	;
-	; Now manually save: r12, sp, fp, gp, r25
+	; (B) Manually saved some regs: r12,r25,r30, sp,fp,gp, ACCL pair
 
 #ifdef CONFIG_ARC_IRQ_NO_AUTOSAVE
 .ifnc \called_from, exception
@@ -57,14 +96,17 @@
 	;  - U mode: retrieve it from AUX_USER_SP
 	;  - K mode: add the offset from current SP where H/w starts auto push
 	;
-	; Utilize the fact that Z bit is set if Intr taken in U mode
+	; 1. Utilize the fact that Z bit is set if Intr taken in U mode
+	; 2. Upon entry SP is always saved (for any inspection, unwinding etc),
+	;    but on return, restored only if U mode
+
 	mov.nz	r9, sp
-	add.nz	r9, r9, SZ_PT_REGS - PT_sp - 4
+	add.nz	r9, r9, SZ_PT_REGS - PT_sp - 4		; K mode SP
 	bnz	1f
 
-	lr	r9, [AUX_USER_SP]
+	lr	r9, [AUX_USER_SP]			; U mode SP
 1:
-	PUSH	r9	; SP
+	PUSH	r9					; SP (pt_regs->sp)
 
 	PUSH	fp
 	PUSH	gp
@@ -85,6 +127,8 @@
 /*------------------------------------------------------------------------*/
 .macro INTERRUPT_EPILOGUE	called_from
 
+	; INPUT: r0 has STAT32 of calling context
+	; INPUT: Z flag set if returning to K mode
 .ifnc \called_from, exception
 	add	sp, sp, 12	; skip BTA/ECR/orig_r0 placeholderss
 .endif
@@ -98,9 +142,10 @@
 	POP	gp
 	POP	fp
 
-	; Don't touch AUX_USER_SP if returning to K mode (Z bit set)
-	; (Z bit set on K mode is inverse of INTERRUPT_PROLOGUE)
-	add.z	sp, sp, 4
+	; Restore SP (into AUX_USER_SP) only if returning to U mode
+	;  - for K mode, it will be implicitly restored as stack is unwound
+	;  - Z flag set on K is inverse of what hardware does on interrupt entry
+	;    but that doesn't really matter
 	bz	1f
 
 	POPAX	AUX_USER_SP
@@ -145,11 +190,11 @@
 /*------------------------------------------------------------------------*/
 .macro EXCEPTION_PROLOGUE
 
-	; Before jumping to Exception Vector, hardware micro-ops did following:
+	; (A) Before jumping to Exception Vector, hardware micro-ops did following:
 	;   1. SP auto-switched to kernel mode stack
-	;   2. STATUS32.Z flag set to U mode at time of interrupt (U:1,K:0)
+	;   2. STATUS32.Z flag set if in U mode at time of exception (U:1,K:0)
 	;
-	; Now manually save the complete reg file
+	; (B) Manually save the complete reg file below
 
 	PUSH	r9		; freeup a register: slot of erstatus
 
@@ -195,12 +240,13 @@
 	PUSHAX	ecr		; r9 contains ECR, expected by EV_Trap
 
 	PUSH	r0		; orig_r0
+	; OUTPUT: r9 has ECR
 .endm
 
 /*------------------------------------------------------------------------*/
 .macro EXCEPTION_EPILOGUE
 
-	; Assumes r0 has PT_status32
+	; INPUT: r0 has STAT32 of calling context
 	btst   r0, STATUS_U_BIT	; Z flag set if K, used in INTERRUPT_EPILOGUE
 
 	add	sp, sp, 8	; orig_r0/ECR don't need restoring
-- 
cgit v1.2.3-58-ga151


From 23c0cbd0c75c3b564850294427fd2be2bc2a015b Mon Sep 17 00:00:00 2001
From: Vineet Gupta <vgupta@synopsys.com>
Date: Tue, 9 Apr 2019 19:16:37 -0700
Subject: ARCv2: entry: push out the Z flag unclobber from common
 EXCEPTION_PROLOGUE

Upon a taken interrupt/exception from User mode, HS hardware auto sets Z flag.
This helps shave a few instructions from EXCEPTION_PROLOGUE by eliding
re-reading ERSTATUS and some bit fiddling.

However TLB Miss Exception handler can clobber the CPU flags and still end
up in EXCEPTION_PROLOGUE in the slow path handling TLB handling case:

   EV_TLBMissD
     do_slow_path_pf
       EV_TLBProtV (aliased to call_do_page_fault)
          EXCEPTION_PROLOGUE

As a result, EXCEPTION_PROLOGUE need to "unclobber" the Z flag which this
patch changes. It is now pushed out to TLB Miss Exception handler.
The reasons beings:

 - The flag restoration is only needed for slowpath TLB Miss Exception
   handling, but currently being in EXCEPTION_PROLOGUE penalizes all
   exceptions such as ProtV and syscall Trap, where Z flag is already
   as expected.

 - Pushing unclobber out to where it was clobbered is much cleaner and
   also serves to document the fact.

 - Makes EXCEPTION_PROLGUE similar to INTERRUPT_PROLOGUE so easier to
   refactor the common parts which is what this series aims to do

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
---
 arch/arc/include/asm/entry-arcv2.h |  8 --------
 arch/arc/mm/tlbex.S                | 11 +++++++++++
 2 files changed, 11 insertions(+), 8 deletions(-)

(limited to 'arch/arc')

diff --git a/arch/arc/include/asm/entry-arcv2.h b/arch/arc/include/asm/entry-arcv2.h
index 1c3520d1fa42..3209a6762960 100644
--- a/arch/arc/include/asm/entry-arcv2.h
+++ b/arch/arc/include/asm/entry-arcv2.h
@@ -225,14 +225,6 @@
 
 	; -- for interrupts, regs above are auto-saved by h/w in that order --
 	; Now do what ISR prologue does (manually save r12, sp, fp, gp, r25)
-	;
-	; Set Z flag if this was from U mode (expected by INTERRUPT_PROLOGUE)
-	; Although H/w exception micro-ops do set Z flag for U mode (just like
-	; for interrupts), it could get clobbered in case we soft land here from
-	; a TLB Miss exception handler (tlbex.S)
-
-	and	r10, r10, STATUS_U_MASK
-	xor.f	0, r10, STATUS_U_MASK
 
 	INTERRUPT_PROLOGUE  exception
 
diff --git a/arch/arc/mm/tlbex.S b/arch/arc/mm/tlbex.S
index 471a97bf492d..c55d95dd2f39 100644
--- a/arch/arc/mm/tlbex.S
+++ b/arch/arc/mm/tlbex.S
@@ -393,6 +393,17 @@ EV_TLBMissD_fast_ret:	; additional label for VDK OS-kit instrumentation
 ;-------- Common routine to call Linux Page Fault Handler -----------
 do_slow_path_pf:
 
+#ifdef CONFIG_ISA_ARCV2
+	; Set Z flag if exception in U mode. Hardware micro-ops do this on any
+	; taken interrupt/exception, and thus is already the case at the entry
+	; above, but ensuing code would have already clobbered.
+	; EXCEPTION_PROLOGUE called in slow path, relies on correct Z flag set
+
+	lr	r2, [erstatus]
+	and	r2, r2, STATUS_U_MASK
+	bxor.f	0, r2, STATUS_U_BIT
+#endif
+
 	; Restore the 4-scratch regs saved by fast path miss handler
 	TLBMISS_RESTORE_REGS
 
-- 
cgit v1.2.3-58-ga151


From ab854bfcd310b5872fe12eb8d3f2c30fe427f8f7 Mon Sep 17 00:00:00 2001
From: Vineet Gupta <vgupta@synopsys.com>
Date: Fri, 10 May 2019 16:24:15 -0700
Subject: ARCv2: entry: avoid a branch

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
---
 arch/arc/include/asm/entry-arcv2.h | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

(limited to 'arch/arc')

diff --git a/arch/arc/include/asm/entry-arcv2.h b/arch/arc/include/asm/entry-arcv2.h
index 3209a6762960..beaf655666cb 100644
--- a/arch/arc/include/asm/entry-arcv2.h
+++ b/arch/arc/include/asm/entry-arcv2.h
@@ -100,12 +100,11 @@
 	; 2. Upon entry SP is always saved (for any inspection, unwinding etc),
 	;    but on return, restored only if U mode
 
+	lr	r9, [AUX_USER_SP]			; U mode SP
+
 	mov.nz	r9, sp
 	add.nz	r9, r9, SZ_PT_REGS - PT_sp - 4		; K mode SP
-	bnz	1f
 
-	lr	r9, [AUX_USER_SP]			; U mode SP
-1:
 	PUSH	r9					; SP (pt_regs->sp)
 
 	PUSH	fp
-- 
cgit v1.2.3-58-ga151


From a4880801a72ecc2dcdfa432f81a754f3e7438567 Mon Sep 17 00:00:00 2001
From: Vineet Gupta <vgupta@synopsys.com>
Date: Wed, 15 May 2019 15:36:46 -0700
Subject: ARCv2: entry: rewrite to enable use of double load/stores LDD/STD

 - the motivation was to be remove blatent copy-paste due to hasty support
   of CONFIG_ARC_IRQ_NO_AUTOSAVE support

 - but with refactoring we could use LDD/STD to greatly optimize the code

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
---
 arch/arc/include/asm/entry-arcv2.h | 297 +++++++++++++++++--------------------
 arch/arc/include/asm/linkage.h     |  18 +++
 arch/arc/kernel/asm-offsets.c      |   7 +
 arch/arc/kernel/entry-arcv2.S      |   4 +-
 4 files changed, 167 insertions(+), 159 deletions(-)

(limited to 'arch/arc')

diff --git a/arch/arc/include/asm/entry-arcv2.h b/arch/arc/include/asm/entry-arcv2.h
index beaf655666cb..0733752ce7fe 100644
--- a/arch/arc/include/asm/entry-arcv2.h
+++ b/arch/arc/include/asm/entry-arcv2.h
@@ -46,7 +46,8 @@
  */
 
 /*------------------------------------------------------------------------*/
-.macro INTERRUPT_PROLOGUE	called_from
+.macro INTERRUPT_PROLOGUE
+
 	; (A) Before jumping to Interrupt Vector, hardware micro-ops did following:
 	;   1. SP auto-switched to kernel mode stack
 	;   2. STATUS32.Z flag set if in U mode at time of interrupt (U:1,K:0)
@@ -57,39 +58,87 @@
 	; (B) Manually saved some regs: r12,r25,r30, sp,fp,gp, ACCL pair
 
 #ifdef CONFIG_ARC_IRQ_NO_AUTOSAVE
-.ifnc \called_from, exception
-	st.as	r9, [sp, -10]	; save r9 in it's final stack slot
-	sub	sp, sp, 12	; skip JLI, LDI, EI
-
-	PUSH	lp_count
-	PUSHAX	lp_start
-	PUSHAX	lp_end
-	PUSH	blink
-
-	PUSH	r11
-	PUSH	r10
-
-	sub	sp, sp, 4	; skip r9
-
-	PUSH	r8
-	PUSH	r7
-	PUSH	r6
-	PUSH	r5
-	PUSH	r4
-	PUSH	r3
-	PUSH	r2
-	PUSH	r1
-	PUSH	r0
-.endif
-#endif
+	; carve pt_regs on stack (case #3), PC/STAT32 already on stack
+	sub	sp, sp, SZ_PT_REGS - 8
 
-#ifdef CONFIG_ARC_HAS_ACCL_REGS
-	PUSH	r59
-	PUSH	r58
+	__SAVE_REGFILE_HARD
+#else
+	; carve pt_regs on stack (case #4), which grew partially already
+	sub	sp, sp, PT_r0
 #endif
 
-	PUSH	r30
-	PUSH	r12
+	__SAVE_REGFILE_SOFT
+.endm
+
+/*------------------------------------------------------------------------*/
+.macro EXCEPTION_PROLOGUE
+
+	; (A) Before jumping to Exception Vector, hardware micro-ops did following:
+	;   1. SP auto-switched to kernel mode stack
+	;   2. STATUS32.Z flag set if in U mode at time of exception (U:1,K:0)
+	;
+	; (B) Manually save the complete reg file below
+
+	sub	sp, sp, SZ_PT_REGS	; carve pt_regs
+
+	; _HARD saves r10 clobbered by _SOFT as scratch hence comes first
+
+	__SAVE_REGFILE_HARD
+	__SAVE_REGFILE_SOFT
+
+	st	r0, [sp]	; orig_r0
+
+	lr	r10, [eret]
+	lr	r11, [erstatus]
+	ST2	r10, r11, PT_ret
+
+	lr	r10, [ecr]
+	lr	r11, [erbta]
+	ST2	r10, r11, PT_event
+	mov	r9, r10
+
+	; OUTPUT: r9 has ECR
+.endm
+
+/*------------------------------------------------------------------------
+ * This macro saves the registers manually which would normally be autosaved
+ * by hardware on taken interrupts. It is used by
+ *   - exception handlers (which don't have autosave)
+ *   - interrupt autosave disabled due to CONFIG_ARC_IRQ_NO_AUTOSAVE
+ */
+.macro __SAVE_REGFILE_HARD
+
+	ST2	r0,  r1,  PT_r0
+	ST2	r2,  r3,  PT_r2
+	ST2	r4,  r5,  PT_r4
+	ST2	r6,  r7,  PT_r6
+	ST2	r8,  r9,  PT_r8
+	ST2	r10, r11, PT_r10
+
+	st	blink, [sp, PT_blink]
+
+	lr	r10, [lp_end]
+	lr	r11, [lp_start]
+	ST2	r10, r11, PT_lpe
+
+	st	lp_count, [sp, PT_lpc]
+
+	; skip JLI, LDI, EI for now
+.endm
+
+/*------------------------------------------------------------------------
+ * This macros saves a bunch of other registers which can't be autosaved for
+ * various reasons:
+ *   - r12: the last caller saved scratch reg since hardware saves in pairs so r0-r11
+ *   - r30: free reg, used by gcc as scratch
+ *   - ACCL/ACCH pair when they exist
+ */
+.macro __SAVE_REGFILE_SOFT
+
+	ST2	gp, fp, PT_r26		; gp (r26), fp (r27)
+
+	st	r12, [sp, PT_sp + 4]
+	st	r30, [sp, PT_sp + 8]
 
 	; Saving pt_regs->sp correctly requires some extra work due to the way
 	; Auto stack switch works
@@ -100,46 +149,32 @@
 	; 2. Upon entry SP is always saved (for any inspection, unwinding etc),
 	;    but on return, restored only if U mode
 
-	lr	r9, [AUX_USER_SP]			; U mode SP
+	lr	r10, [AUX_USER_SP]	; U mode SP
 
-	mov.nz	r9, sp
-	add.nz	r9, r9, SZ_PT_REGS - PT_sp - 4		; K mode SP
+	; ISA requires ADD.nz to have same dest and src reg operands
+	mov.nz	r10, sp
+	add.nz	r10, r10, SZ_PT_REGS	; K mode SP
 
-	PUSH	r9					; SP (pt_regs->sp)
-
-	PUSH	fp
-	PUSH	gp
+	st	r10, [sp, PT_sp]	; SP (pt_regs->sp)
 
 #ifdef CONFIG_ARC_CURR_IN_REG
-	PUSH	r25			; user_r25
+	st	r25, [sp, PT_user_r25]
 	GET_CURR_TASK_ON_CPU	r25
-#else
-	sub	sp, sp, 4
 #endif
 
-.ifnc \called_from, exception
-	sub	sp, sp, 12	; BTA/ECR/orig_r0 placeholder per pt_regs
-.endif
+#ifdef CONFIG_ARC_HAS_ACCL_REGS
+	ST2	r58, r59, PT_sp + 12
+#endif
 
 .endm
 
 /*------------------------------------------------------------------------*/
-.macro INTERRUPT_EPILOGUE	called_from
+.macro __RESTORE_REGFILE_SOFT
 
-	; INPUT: r0 has STAT32 of calling context
-	; INPUT: Z flag set if returning to K mode
-.ifnc \called_from, exception
-	add	sp, sp, 12	; skip BTA/ECR/orig_r0 placeholderss
-.endif
-
-#ifdef CONFIG_ARC_CURR_IN_REG
-	POP	r25
-#else
-	add	sp, sp, 4
-#endif
+	LD2	gp, fp, PT_r26		; gp (r26), fp (r27)
 
-	POP	gp
-	POP	fp
+	ld	r12, [sp, PT_sp + 4]
+	ld	r30, [sp, PT_sp + 8]
 
 	; Restore SP (into AUX_USER_SP) only if returning to U mode
 	;  - for K mode, it will be implicitly restored as stack is unwound
@@ -147,129 +182,77 @@
 	;    but that doesn't really matter
 	bz	1f
 
-	POPAX	AUX_USER_SP
+	ld	r10, [sp, PT_sp]	; SP (pt_regs->sp)
+	sr	r10, [AUX_USER_SP]
 1:
-	POP	r12
-	POP	r30
 
-#ifdef CONFIG_ARC_HAS_ACCL_REGS
-	POP	r58
-	POP	r59
+#ifdef CONFIG_ARC_CURR_IN_REG
+	ld	r25, [sp, PT_user_r25]
 #endif
 
-#ifdef CONFIG_ARC_IRQ_NO_AUTOSAVE
-.ifnc \called_from, exception
-	POP	r0
-	POP	r1
-	POP	r2
-	POP	r3
-	POP	r4
-	POP	r5
-	POP	r6
-	POP	r7
-	POP	r8
-	POP	r9
-	POP	r10
-	POP	r11
-
-	POP	blink
-	POPAX	lp_end
-	POPAX	lp_start
-
-	POP	r9
-	mov	lp_count, r9
-
-	add	sp, sp, 12	; skip JLI, LDI, EI
-	ld.as	r9, [sp, -10]	; reload r9 which got clobbered
-.endif
+#ifdef CONFIG_ARC_HAS_ACCL_REGS
+	LD2	r58, r59, PT_sp + 12
 #endif
-
 .endm
 
 /*------------------------------------------------------------------------*/
-.macro EXCEPTION_PROLOGUE
+.macro __RESTORE_REGFILE_HARD
 
-	; (A) Before jumping to Exception Vector, hardware micro-ops did following:
-	;   1. SP auto-switched to kernel mode stack
-	;   2. STATUS32.Z flag set if in U mode at time of exception (U:1,K:0)
-	;
-	; (B) Manually save the complete reg file below
+	ld	blink, [sp, PT_blink]
 
-	PUSH	r9		; freeup a register: slot of erstatus
+	LD2	r10, r11, PT_lpe
+	sr	r10, [lp_end]
+	sr	r11, [lp_start]
 
-	PUSHAX	eret
-	sub	sp, sp, 12	; skip JLI, LDI, EI
-	PUSH	lp_count
-	PUSHAX	lp_start
-	PUSHAX	lp_end
-	PUSH	blink
+	ld	r10, [sp, PT_lpc]	; lp_count can't be target of LD
+	mov	lp_count, r10
 
-	PUSH	r11
-	PUSH	r10
+	LD2	r0,  r1,  PT_r0
+	LD2	r2,  r3,  PT_r2
+	LD2	r4,  r5,  PT_r4
+	LD2	r6,  r7,  PT_r6
+	LD2	r8,  r9,  PT_r8
+	LD2	r10, r11, PT_r10
+.endm
 
-	ld.as	r9,  [sp, 10]	; load stashed r9 (status32 stack slot)
-	lr	r10, [erstatus]
-	st.as	r10, [sp, 10]	; save status32 at it's right stack slot
 
-	PUSH	r9
-	PUSH	r8
-	PUSH	r7
-	PUSH	r6
-	PUSH	r5
-	PUSH	r4
-	PUSH	r3
-	PUSH	r2
-	PUSH	r1
-	PUSH	r0
+/*------------------------------------------------------------------------*/
+.macro INTERRUPT_EPILOGUE
 
-	; -- for interrupts, regs above are auto-saved by h/w in that order --
-	; Now do what ISR prologue does (manually save r12, sp, fp, gp, r25)
+	; INPUT: r0 has STAT32 of calling context
+	; INPUT: Z flag set if returning to K mode
 
-	INTERRUPT_PROLOGUE  exception
+	; _SOFT clobbers r10 restored by _HARD hence the order
 
-	PUSHAX	erbta
-	PUSHAX	ecr		; r9 contains ECR, expected by EV_Trap
+	__RESTORE_REGFILE_SOFT
+
+#ifdef CONFIG_ARC_IRQ_NO_AUTOSAVE
+	__RESTORE_REGFILE_HARD
+	add	sp, sp, SZ_PT_REGS - 8
+#else
+	add	sp, sp, PT_r0
+#endif
 
-	PUSH	r0		; orig_r0
-	; OUTPUT: r9 has ECR
 .endm
 
 /*------------------------------------------------------------------------*/
 .macro EXCEPTION_EPILOGUE
 
 	; INPUT: r0 has STAT32 of calling context
-	btst   r0, STATUS_U_BIT	; Z flag set if K, used in INTERRUPT_EPILOGUE
-
-	add	sp, sp, 8	; orig_r0/ECR don't need restoring
-	POPAX	erbta
-
-	INTERRUPT_EPILOGUE  exception
-
-	POP	r0
-	POP	r1
-	POP	r2
-	POP	r3
-	POP	r4
-	POP	r5
-	POP	r6
-	POP	r7
-	POP	r8
-	POP	r9
-	POP	r10
-	POP	r11
-
-	POP	blink
-	POPAX	lp_end
-	POPAX	lp_start
-
-	POP	r9
-	mov	lp_count, r9
-
-	add	sp, sp, 12	; skip JLI, LDI, EI
-	POPAX	eret
-	POPAX	erstatus
-
-	ld.as	r9, [sp, -12]	; reload r9 which got clobbered
+
+	btst	r0, STATUS_U_BIT	; Z flag set if K, used in restoring SP
+
+	ld	r10, [sp, PT_event + 4]
+	sr	r10, [erbta]
+
+	LD2	r10, r11, PT_ret
+	sr	r10, [eret]
+	sr	r11, [erstatus]
+
+	__RESTORE_REGFILE_SOFT
+	__RESTORE_REGFILE_HARD
+
+	add	sp, sp, SZ_PT_REGS
 .endm
 
 .macro FAKE_RET_FROM_EXCPN
diff --git a/arch/arc/include/asm/linkage.h b/arch/arc/include/asm/linkage.h
index 54f5ec5c1759..a0eeb9f8f0a9 100644
--- a/arch/arc/include/asm/linkage.h
+++ b/arch/arc/include/asm/linkage.h
@@ -10,6 +10,24 @@
 
 #ifdef __ASSEMBLY__
 
+.macro ST2 e, o, off
+#ifdef CONFIG_ARC_HAS_LL64
+	std	\e, [sp, \off]
+#else
+	st	\e, [sp, \off]
+	st	\o, [sp, \off+4]
+#endif
+.endm
+
+.macro LD2 e, o, off
+#ifdef CONFIG_ARC_HAS_LL64
+	ldd	\e, [sp, \off]
+#else
+	ld	\e, [sp, \off]
+	ld	\o, [sp, \off+4]
+#endif
+.endm
+
 #define ASM_NL		 `	/* use '`' to mark new line in macro */
 
 /* annotation for data we want in DCCM - if enabled in .config */
diff --git a/arch/arc/kernel/asm-offsets.c b/arch/arc/kernel/asm-offsets.c
index dba116535005..1f621e416521 100644
--- a/arch/arc/kernel/asm-offsets.c
+++ b/arch/arc/kernel/asm-offsets.c
@@ -55,7 +55,14 @@ int main(void)
 	DEFINE(PT_r5, offsetof(struct pt_regs, r5));
 	DEFINE(PT_r6, offsetof(struct pt_regs, r6));
 	DEFINE(PT_r7, offsetof(struct pt_regs, r7));
+	DEFINE(PT_r8, offsetof(struct pt_regs, r8));
+	DEFINE(PT_r10, offsetof(struct pt_regs, r10));
+	DEFINE(PT_r26, offsetof(struct pt_regs, r26));
 	DEFINE(PT_ret, offsetof(struct pt_regs, ret));
+	DEFINE(PT_blink, offsetof(struct pt_regs, blink));
+	DEFINE(PT_lpe, offsetof(struct pt_regs, lp_end));
+	DEFINE(PT_lpc, offsetof(struct pt_regs, lp_count));
+	DEFINE(PT_user_r25, offsetof(struct pt_regs, user_r25));
 
 	DEFINE(SZ_CALLEE_REGS, sizeof(struct callee_regs));
 	DEFINE(SZ_PT_REGS, sizeof(struct pt_regs));
diff --git a/arch/arc/kernel/entry-arcv2.S b/arch/arc/kernel/entry-arcv2.S
index 14254b866fdc..0fc408ec0814 100644
--- a/arch/arc/kernel/entry-arcv2.S
+++ b/arch/arc/kernel/entry-arcv2.S
@@ -67,7 +67,7 @@ reserved:
 
 ENTRY(handle_interrupt)
 
-	INTERRUPT_PROLOGUE  irq
+	INTERRUPT_PROLOGUE
 
 	# irq control APIs local_irq_save/restore/disable/enable fiddle with
 	# global interrupt enable bits in STATUS32 (.IE for 1 prio, .E[] for 2 prio)
@@ -223,7 +223,7 @@ debug_marker_l1:
 	bset.nz	r11, r11, AUX_IRQ_ACT_BIT_U	; NZ means U
 	sr	r11, [AUX_IRQ_ACT]
 
-	INTERRUPT_EPILOGUE  irq
+	INTERRUPT_EPILOGUE
 	rtie
 
 ;####### Return from Exception / pure kernel mode #######
-- 
cgit v1.2.3-58-ga151


From 68e5c6f073bcf70da5f8eef88eb2d98f7c560bb6 Mon Sep 17 00:00:00 2001
From: Vineet Gupta <vgupta@synopsys.com>
Date: Wed, 15 May 2019 16:08:10 -0700
Subject: ARC: entry: EV_Trap expects r10 (vs. r9) to have exception cause

avoids 1 MOV instruction in light of double load/store code

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
---
 arch/arc/include/asm/entry-arcv2.h   | 3 +--
 arch/arc/include/asm/entry-compact.h | 4 ++--
 arch/arc/kernel/entry-compact.S      | 2 +-
 arch/arc/kernel/entry.S              | 4 ++--
 4 files changed, 6 insertions(+), 7 deletions(-)

(limited to 'arch/arc')

diff --git a/arch/arc/include/asm/entry-arcv2.h b/arch/arc/include/asm/entry-arcv2.h
index 0733752ce7fe..f5ae394ebe06 100644
--- a/arch/arc/include/asm/entry-arcv2.h
+++ b/arch/arc/include/asm/entry-arcv2.h
@@ -95,9 +95,8 @@
 	lr	r10, [ecr]
 	lr	r11, [erbta]
 	ST2	r10, r11, PT_event
-	mov	r9, r10
 
-	; OUTPUT: r9 has ECR
+	; OUTPUT: r10 has ECR expected by EV_Trap
 .endm
 
 /*------------------------------------------------------------------------
diff --git a/arch/arc/include/asm/entry-compact.h b/arch/arc/include/asm/entry-compact.h
index 66ba1bf21d28..66a292335ee6 100644
--- a/arch/arc/include/asm/entry-compact.h
+++ b/arch/arc/include/asm/entry-compact.h
@@ -195,8 +195,8 @@
 	PUSHAX  CTOP_AUX_EFLAGS
 #endif
 
-	lr	r9, [ecr]
-	st      r9, [sp, PT_event]    /* EV_Trap expects r9 to have ECR */
+	lr	r10, [ecr]
+	st      r10, [sp, PT_event]    /* EV_Trap expects r10 to have ECR */
 .endm
 
 /*--------------------------------------------------------------
diff --git a/arch/arc/kernel/entry-compact.S b/arch/arc/kernel/entry-compact.S
index 7fe59880c16b..5cb0cd7e4eab 100644
--- a/arch/arc/kernel/entry-compact.S
+++ b/arch/arc/kernel/entry-compact.S
@@ -256,7 +256,7 @@ ENTRY(EV_TLBProtV)
 
 	EXCEPTION_PROLOGUE
 
-	mov r2, r9	; ECR set into r9 already
+	mov r2, r10	; ECR set into r10 already
 	lr  r0, [efa]	; Faulting Data address (not part of pt_regs saved above)
 
 	; Exception auto-disables further Intr/exceptions.
diff --git a/arch/arc/kernel/entry.S b/arch/arc/kernel/entry.S
index a2bfacbcfce1..72be01270e24 100644
--- a/arch/arc/kernel/entry.S
+++ b/arch/arc/kernel/entry.S
@@ -232,8 +232,8 @@ ENTRY(EV_Trap)
 	EXCEPTION_PROLOGUE
 
 	;============ TRAP 1   :breakpoints
-	; Check ECR for trap with arg (PROLOGUE ensures r9 has ECR)
-	bmsk.f 0, r9, 7
+	; Check ECR for trap with arg (PROLOGUE ensures r10 has ECR)
+	bmsk.f 0, r10, 7
 	bnz    trap_with_param
 
 	;============ TRAP  (no param): syscall top level
-- 
cgit v1.2.3-58-ga151


From 75370ad44075e832966a6dd1f6a649b8aee2325b Mon Sep 17 00:00:00 2001
From: Vineet Gupta <vgupta@synopsys.com>
Date: Wed, 22 May 2019 08:47:13 -0700
Subject: ARCv2: entry: simplify return to Delay Slot via interrupt

Commit 4255b07f2c9c43540 ("ARCv2: STAR 9000793984: Handle return
from intr to Delay Slot") involved a complex 2 staged trampoline.

Apparently this can be greatly simplified by returning from pure
kernel mode (iso interrupt) so drop to pure kernel mdoe and execute
the normal exception return path.

Testing this was a bit of challenge as return from interrupt is rarely
executed now after commit 4de0e52867d83105767 ("ARCv2: STAR 9000814690:
Really Re-enable interrupts to avoid deadlocks"). That fix is necessary
evil and pct interrupts etc do exercise intr return path.
Anyhow after a revert of above in my local test setup I was able to hit
this case and verify the patch works.

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
---
 arch/arc/kernel/entry-arcv2.S | 58 ++++++++-----------------------------------
 1 file changed, 10 insertions(+), 48 deletions(-)

(limited to 'arch/arc')

diff --git a/arch/arc/kernel/entry-arcv2.S b/arch/arc/kernel/entry-arcv2.S
index 0fc408ec0814..12d5f12d10d2 100644
--- a/arch/arc/kernel/entry-arcv2.S
+++ b/arch/arc/kernel/entry-arcv2.S
@@ -79,7 +79,7 @@ ENTRY(handle_interrupt)
 	#
 	# Note this disable is only for consistent book-keeping as further interrupts
 	# will be disabled anyways even w/o this. Hardware tracks active interrupts
-	# seperately in AUX_IRQ_ACTIVE.active and will not take new interrupts
+	# seperately in AUX_IRQ_ACT.active and will not take new interrupts
 	# unless this one returns (or higher prio becomes pending in 2-prio scheme)
 
 	IRQ_DISABLE
@@ -200,17 +200,18 @@ restore_regs:
 	ld	r0, [sp, PT_status32]	; U/K mode at time of entry
 	lr	r10, [AUX_IRQ_ACT]
 
-	bmsk	r11, r10, 15	; AUX_IRQ_ACT.ACTIVE
+	bmsk	r11, r10, 15		; extract AUX_IRQ_ACT.active
 	breq	r11, 0, .Lexcept_ret	; No intr active, ret from Exception
 
 ;####### Return from Intr #######
 
+.Lisr_ret:
+
 debug_marker_l1:
 	; bbit1.nt r0, STATUS_DE_BIT, .Lintr_ret_to_delay_slot
 	btst	r0, STATUS_DE_BIT		; Z flag set if bit clear
 	bnz	.Lintr_ret_to_delay_slot	; branch if STATUS_DE_BIT set
 
-.Lisr_ret_fast_path:
 	; Handle special case #1: (Entry via Exception, Return via IRQ)
 	;
 	; Exception in U mode, preempted in kernel, Intr taken (K mode), orig
@@ -244,8 +245,8 @@ debug_marker_syscall:
 ;
 ; IRQ RTIE won't reliably restore DE bit and/or BTA, needs workaround
 ;
-; Solution is return from Intr w/o any delay slot quirks into a kernel trampoline
-; and from pure kernel mode return to delay slot which handles DS bit/BTA correctly
+; Solution is to drop out of interrupt context into pure kernel mode
+; and return from pure kernel mode which does right things for delay slot
 
 .Lintr_ret_to_delay_slot:
 debug_marker_ds:
@@ -254,48 +255,9 @@ debug_marker_ds:
 	add	r2, r2, 1
 	st	r2, [@intr_to_DE_cnt]
 
-	ld	r2, [sp, PT_ret]
-	ld	r3, [sp, PT_status32]
-
-	; STAT32 for Int return created from scratch
-	; (No delay dlot, disable Further intr in trampoline)
-
-	bic  	r0, r3, STATUS_U_MASK|STATUS_DE_MASK|STATUS_IE_MASK|STATUS_L_MASK
-	st	r0, [sp, PT_status32]
-
-	mov	r1, .Lintr_ret_to_delay_slot_2
-	st	r1, [sp, PT_ret]
-
-	; Orig exception PC/STAT32 safekept @orig_r0 and @event stack slots
-	st	r2, [sp, 0]
-	st	r3, [sp, 4]
-
-	b	.Lisr_ret_fast_path
-
-.Lintr_ret_to_delay_slot_2:
-	; Trampoline to restore orig exception PC/STAT32/BTA/AUX_USER_SP
-	sub	sp, sp, SZ_PT_REGS
-	st	r9, [sp, -4]
-
-	ld	r9, [sp, 0]
-	sr	r9, [eret]
-
-	ld	r9, [sp, 4]
-	sr	r9, [erstatus]
-
-	; restore AUX_USER_SP if returning to U mode
-	bbit0	r9, STATUS_U_BIT, 1f
-	ld	r9, [sp, PT_sp]
-	sr	r9, [AUX_USER_SP]
-
-1:
-	ld	r9, [sp, 8]
-	sr	r9, [erbta]
-
-	ld	r9, [sp, -4]
-	add	sp, sp, SZ_PT_REGS
-
-	; return from pure kernel mode to delay slot
-	rtie
+	; drop out of interrupt context (clear AUX_IRQ_ACT.active)
+	bmskn	r11, r10, 15
+	sr	r11, [AUX_IRQ_ACT]
+	b	.Lexcept_ret
 
 END(ret_from_exception)
-- 
cgit v1.2.3-58-ga151


From 94b8beb972c524f42078281c9950ed3a946455fa Mon Sep 17 00:00:00 2001
From: Alexey Brodkin <Alexey.Brodkin@synopsys.com>
Date: Tue, 2 Jul 2019 19:40:33 +0300
Subject: ARC: [haps] Add Virtio support

As a preparation for QEMU usage for ARC let's add basic Virtio-MMIO
peripherals support for the platform we're going to use.

For now we add 5 Virtio slots in .dts and enable block and network devices
via Virtio-MMIO.

Note even though typically Virtio register set fits in 0x200 bytes
we "allocate" here 0x2000 so that it matches ARC's default 8KiB page size
and so remapping of that area is done clearly.

We also enable DEVTMPFS automount for more convenient use
of external root file-stystem. Before that we used to use built-in
Initramfs which didn't automount DEVTMPFS anyways so we didn't need
that option, while now it starts making sense.

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Cc: Rob Herring <robh+dt@kernel.org>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
---
 arch/arc/boot/dts/haps_hs.dts      | 30 ++++++++++++++++++++++++++++++
 arch/arc/configs/haps_hs_defconfig |  5 ++++-
 2 files changed, 34 insertions(+), 1 deletion(-)

(limited to 'arch/arc')

diff --git a/arch/arc/boot/dts/haps_hs.dts b/arch/arc/boot/dts/haps_hs.dts
index 1ebfa046492b..44bc522fdec8 100644
--- a/arch/arc/boot/dts/haps_hs.dts
+++ b/arch/arc/boot/dts/haps_hs.dts
@@ -62,5 +62,35 @@
 			#interrupt-cells = <1>;
 			interrupts = <20>;
 		};
+
+		virtio0: virtio@f0100000 {
+			compatible = "virtio,mmio";
+			reg = <0xf0100000 0x2000>;
+			interrupts = <31>;
+		};
+
+		virtio1: virtio@f0102000 {
+			compatible = "virtio,mmio";
+			reg = <0xf0102000 0x2000>;
+			interrupts = <32>;
+		};
+
+		virtio2: virtio@f0104000 {
+			compatible = "virtio,mmio";
+			reg = <0xf0104000 0x2000>;
+			interrupts = <33>;
+		};
+
+		virtio3: virtio@f0106000 {
+			compatible = "virtio,mmio";
+			reg = <0xf0106000 0x2000>;
+			interrupts = <34>;
+		};
+
+		virtio4: virtio@f0108000 {
+			compatible = "virtio,mmio";
+			reg = <0xf0108000 0x2000>;
+			interrupts = <35>;
+		};
 	};
 };
diff --git a/arch/arc/configs/haps_hs_defconfig b/arch/arc/configs/haps_hs_defconfig
index b117e6c16d41..436f2135bdc1 100644
--- a/arch/arc/configs/haps_hs_defconfig
+++ b/arch/arc/configs/haps_hs_defconfig
@@ -35,10 +35,12 @@ CONFIG_INET=y
 # CONFIG_IPV6 is not set
 # CONFIG_WIRELESS is not set
 CONFIG_DEVTMPFS=y
+CONFIG_DEVTMPFS_MOUNT=y
 # CONFIG_STANDALONE is not set
 # CONFIG_PREVENT_FIRMWARE_BUILD is not set
-# CONFIG_BLK_DEV is not set
+CONFIG_VIRTIO_BLK=y
 CONFIG_NETDEVICES=y
+CONFIG_VIRTIO_NET=y
 # CONFIG_NET_VENDOR_ARC is not set
 # CONFIG_NET_VENDOR_BROADCOM is not set
 # CONFIG_NET_VENDOR_INTEL is not set
@@ -68,6 +70,7 @@ CONFIG_FRAMEBUFFER_CONSOLE=y
 CONFIG_LOGO=y
 # CONFIG_HID is not set
 # CONFIG_USB_SUPPORT is not set
+CONFIG_VIRTIO_MMIO=y
 # CONFIG_IOMMU_SUPPORT is not set
 CONFIG_EXT2_FS=y
 CONFIG_EXT2_FS_XATTR=y
-- 
cgit v1.2.3-58-ga151


From fd5de2721ea7d16e2b16c4049ac49f229551b290 Mon Sep 17 00:00:00 2001
From: Arnd Bergmann <arnd@arndb.de>
Date: Wed, 3 Jul 2019 15:39:25 +0200
Subject: ARC: hide unused function unw_hdr_alloc

As kernelci.org reports, this function is not used in
vdk_hs38_defconfig:

arch/arc/kernel/unwind.c:188:14: warning: 'unw_hdr_alloc' defined but not used [-Wunused-function]

Fixes: bc79c9a72165 ("ARC: dw2 unwind: Reinstante unwinding out of modules")
Link: https://kernelci.org/build/id/5d1cae3f59b514300340c132/logs/
Cc: stable@vger.kernel.org
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
---
 arch/arc/kernel/unwind.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

(limited to 'arch/arc')

diff --git a/arch/arc/kernel/unwind.c b/arch/arc/kernel/unwind.c
index 182ce67dfe10..c2663fce7f6c 100644
--- a/arch/arc/kernel/unwind.c
+++ b/arch/arc/kernel/unwind.c
@@ -181,11 +181,6 @@ static void *__init unw_hdr_alloc_early(unsigned long sz)
 	return memblock_alloc_from(sz, sizeof(unsigned int), MAX_DMA_ADDRESS);
 }
 
-static void *unw_hdr_alloc(unsigned long sz)
-{
-	return kmalloc(sz, GFP_KERNEL);
-}
-
 static void init_unwind_table(struct unwind_table *table, const char *name,
 			      const void *core_start, unsigned long core_size,
 			      const void *init_start, unsigned long init_size,
@@ -366,6 +361,10 @@ ret_err:
 }
 
 #ifdef CONFIG_MODULES
+static void *unw_hdr_alloc(unsigned long sz)
+{
+	return kmalloc(sz, GFP_KERNEL);
+}
 
 static struct unwind_table *last_table;
 
-- 
cgit v1.2.3-58-ga151


From aab128d006e709954f2a67b5e27a4c587a0584bd Mon Sep 17 00:00:00 2001
From: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Date: Fri, 7 Jun 2019 17:48:00 +0300
Subject: ARC: [plat-hsdk]: enable DW SPI controller

HSDK SoC has DW SPI controller. Enable it in preparation of
enabling on-board SPI peripherals.

Acked-by: Alexey Brodkin <abrodkin@synopsys.com>
Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
---
 arch/arc/boot/dts/hsdk.dts      | 14 ++++++++++++++
 arch/arc/configs/hsdk_defconfig |  3 +++
 2 files changed, 17 insertions(+)

(limited to 'arch/arc')

diff --git a/arch/arc/boot/dts/hsdk.dts b/arch/arc/boot/dts/hsdk.dts
index 9a45cb093096..bfc7f5f5d6f2 100644
--- a/arch/arc/boot/dts/hsdk.dts
+++ b/arch/arc/boot/dts/hsdk.dts
@@ -8,6 +8,7 @@
  */
 /dts-v1/;
 
+#include <dt-bindings/gpio/gpio.h>
 #include <dt-bindings/reset/snps,hsdk-reset.h>
 
 / {
@@ -252,6 +253,19 @@
 			dma-coherent;
 		};
 
+		spi0: spi@20000 {
+			compatible = "snps,dw-apb-ssi";
+			reg = <0x20000 0x100>;
+			#address-cells = <1>;
+			#size-cells = <0>;
+			interrupts = <16>;
+			num-cs = <2>;
+			reg-io-width = <4>;
+			clocks = <&input_clk>;
+			cs-gpios = <&creg_gpio 0 GPIO_ACTIVE_LOW>,
+				   <&creg_gpio 1 GPIO_ACTIVE_LOW>;
+		};
+
 		creg_gpio: gpio@14b0 {
 			compatible = "snps,creg-gpio-hsdk";
 			reg = <0x14b0 0x4>;
diff --git a/arch/arc/configs/hsdk_defconfig b/arch/arc/configs/hsdk_defconfig
index c8fb5d60c53f..d01b567328dc 100644
--- a/arch/arc/configs/hsdk_defconfig
+++ b/arch/arc/configs/hsdk_defconfig
@@ -46,6 +46,9 @@ CONFIG_SERIAL_8250_CONSOLE=y
 CONFIG_SERIAL_8250_DW=y
 CONFIG_SERIAL_OF_PLATFORM=y
 # CONFIG_HW_RANDOM is not set
+CONFIG_SPI=y
+CONFIG_SPI_DESIGNWARE=y
+CONFIG_SPI_DW_MMIO=y
 CONFIG_GPIOLIB=y
 CONFIG_GPIO_SYSFS=y
 CONFIG_GPIO_DWAPB=y
-- 
cgit v1.2.3-58-ga151


From 24a20b0a443fd485852d51d08e98bbd9d212e0ec Mon Sep 17 00:00:00 2001
From: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Date: Fri, 5 Jul 2019 19:24:09 +0300
Subject: ARC: [plat-hsdk]: Enable AXI DW DMAC in defconfig

For some reasons my previous patch "Enable AXI DW DMAC support"
was applied only partially (only device tree part).
So enable AXI DW DMAC in HSDK defconfig to be able to use it in
verification flow.

Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
---
 arch/arc/configs/hsdk_defconfig | 2 ++
 1 file changed, 2 insertions(+)

(limited to 'arch/arc')

diff --git a/arch/arc/configs/hsdk_defconfig b/arch/arc/configs/hsdk_defconfig
index d01b567328dc..403125d9c9a3 100644
--- a/arch/arc/configs/hsdk_defconfig
+++ b/arch/arc/configs/hsdk_defconfig
@@ -69,6 +69,8 @@ CONFIG_MMC=y
 CONFIG_MMC_SDHCI=y
 CONFIG_MMC_SDHCI_PLTFM=y
 CONFIG_MMC_DW=y
+CONFIG_DMADEVICES=y
+CONFIG_DW_AXI_DMAC=y
 CONFIG_EXT3_FS=y
 CONFIG_VFAT_FS=y
 CONFIG_TMPFS=y
-- 
cgit v1.2.3-58-ga151