Merge tag 'arc-5.0-final' of git://git.kernel.org/pub/scm/linux/kerne…

…l/git/vgupta/arc

Pull ARC fixes from Vineet Gupta:
 "Fixes for ARC for 5.0, bunch of those are stable fodder anyways so
  sooner the better.

   - Fix memcpy to prevent prefetchw beyond end of buffer [Eugeniy]

   - Enable unaligned access early to prevent exceptions given newer gcc
     code gen [Eugeniy]

   - Tighten up uboot arg checking to prevent false negatives and also
     allow both jtag and bootloading to coexist w/o config option as
     needed by kernelCi folks [Eugeniy]

   - Set slab alignment to 8 for ARC to avoid the atomic64_t unalign
     [Alexey]

   - Disable regfile auto save on interrupts on HSDK platform due to a
     silicon issue [Vineet]

   - Avoid HS38x boot printing crash by not reading HS48x only reg
     [Vineet]"

* tag 'arc-5.0-final' of git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc:
  ARCv2: don't assume core 0x54 has dual issue
  ARC: define ARCH_SLAB_MINALIGN = 8
  ARC: enable uboot support unconditionally
  ARC: U-boot: check arguments paranoidly
  ARCv2: support manual regfile save on interrupts
  ARC: uacces: remove lp_start, lp_end from clobber list
  ARC: fix actionpoints configuration detection
  ARCv2: lib: memcpy: fix doing prefetchw outside of buffer
  ARCv2: Enable unaligned access in early ASM code

arch/arc/Kconfig

@@ -191,7 +191,6 @@ config NR_CPUS
 
 config ARC_SMP_HALT_ON_RESET
 	bool "Enable Halt-on-reset boot mode"
-	default y if ARC_UBOOT_SUPPORT
 	help
 	  In SMP configuration cores can be configured as Halt-on-reset
 	  or they could all start at same time. For Halt-on-reset, non
@@ -407,6 +406,14 @@ config ARC_HAS_ACCL_REGS
 	  (also referred to as r58:r59). These can also be used by gcc as GPR so
 	  kernel needs to save/restore per process
 
+config ARC_IRQ_NO_AUTOSAVE
+	bool "Disable hardware autosave regfile on interrupts"
+	default n
+	help
+	  On HS cores, taken interrupt auto saves the regfile on stack.
+	  This is programmable and can be optionally disabled in which case
+	  software INTERRUPT_PROLOGUE/EPILGUE do the needed work
+
 endif	# ISA_ARCV2
 
 endmenu   # "ARC CPU Configuration"
@@ -515,17 +522,6 @@ config ARC_DBG_TLB_PARANOIA
 
 endif
 
-config ARC_UBOOT_SUPPORT
-	bool "Support uboot arg Handling"
-	help
-	  ARC Linux by default checks for uboot provided args as pointers to
-	  external cmdline or DTB. This however breaks in absence of uboot,
-	  when booting from Metaware debugger directly, as the registers are
-	  not zeroed out on reset by mdb and/or ARCv2 based cores. The bogus
-	  registers look like uboot args to kernel which then chokes.
-	  So only enable the uboot arg checking/processing if users are sure
-	  of uboot being in play.
-
 config ARC_BUILTIN_DTB_NAME
 	string "Built in DTB"
 	help

arch/arc/configs/nps_defconfig

@@ -31,7 +31,6 @@ CONFIG_ARC_CACHE_LINE_SHIFT=5
 # CONFIG_ARC_HAS_LLSC is not set
 CONFIG_ARC_KVADDR_SIZE=402
 CONFIG_ARC_EMUL_UNALIGNED=y
-CONFIG_ARC_UBOOT_SUPPORT=y
 CONFIG_PREEMPT=y
 CONFIG_NET=y
 CONFIG_UNIX=y

arch/arc/configs/vdk_hs38_defconfig

@@ -13,7 +13,6 @@ CONFIG_PARTITION_ADVANCED=y
 CONFIG_ARC_PLAT_AXS10X=y
 CONFIG_AXS103=y
 CONFIG_ISA_ARCV2=y
-CONFIG_ARC_UBOOT_SUPPORT=y
 CONFIG_ARC_BUILTIN_DTB_NAME="vdk_hs38"
 CONFIG_PREEMPT=y
 CONFIG_NET=y

arch/arc/configs/vdk_hs38_smp_defconfig

@@ -15,8 +15,6 @@ CONFIG_AXS103=y
 CONFIG_ISA_ARCV2=y
 CONFIG_SMP=y
 # CONFIG_ARC_TIMERS_64BIT is not set
-# CONFIG_ARC_SMP_HALT_ON_RESET is not set
-CONFIG_ARC_UBOOT_SUPPORT=y
 CONFIG_ARC_BUILTIN_DTB_NAME="vdk_hs38_smp"
 CONFIG_PREEMPT=y
 CONFIG_NET=y

arch/arc/include/asm/arcregs.h

@@ -151,6 +151,14 @@ struct bcr_isa_arcv2 {
 #endif
 };
 
+struct bcr_uarch_build_arcv2 {
+#ifdef CONFIG_CPU_BIG_ENDIAN
+	unsigned int pad:8, prod:8, maj:8, min:8;
+#else
+	unsigned int min:8, maj:8, prod:8, pad:8;
+#endif
+};
+
 struct bcr_mpy {
 #ifdef CONFIG_CPU_BIG_ENDIAN
 	unsigned int pad:8, x1616:8, dsp:4, cycles:2, type:2, ver:8;

arch/arc/include/asm/cache.h

@@ -52,6 +52,17 @@
 #define cache_line_size()	SMP_CACHE_BYTES
 #define ARCH_DMA_MINALIGN	SMP_CACHE_BYTES
 
+/*
+ * Make sure slab-allocated buffers are 64-bit aligned when atomic64_t uses
+ * ARCv2 64-bit atomics (LLOCKD/SCONDD). This guarantess runtime 64-bit
+ * alignment for any atomic64_t embedded in buffer.
+ * Default ARCH_SLAB_MINALIGN is __alignof__(long long) which has a relaxed
+ * value of 4 (and not 8) in ARC ABI.
+ */
+#if defined(CONFIG_ARC_HAS_LL64) && defined(CONFIG_ARC_HAS_LLSC)
+#define ARCH_SLAB_MINALIGN	8
+#endif
+
 extern void arc_cache_init(void);
 extern char *arc_cache_mumbojumbo(int cpu_id, char *buf, int len);
 extern void read_decode_cache_bcr(void);

arch/arc/include/asm/entry-arcv2.h

@@ -17,6 +17,33 @@
 	;
 	; Now manually save: r12, sp, fp, gp, r25
 
+#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
+
 #ifdef CONFIG_ARC_HAS_ACCL_REGS
 	PUSH	r59
 	PUSH	r58
@@ -86,6 +113,33 @@
 	POP	r59
 #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
+#endif
+
 .endm
 
 /*------------------------------------------------------------------------*/

arch/arc/include/asm/uaccess.h

@@ -207,7 +207,7 @@ raw_copy_from_user(void *to, const void __user *from, unsigned long n)
 		*/
 		  "=&r" (tmp), "+r" (to), "+r" (from)
 		:
-		: "lp_count", "lp_start", "lp_end", "memory");
+		: "lp_count", "memory");
 
 		return n;
 	}
@@ -433,7 +433,7 @@ raw_copy_to_user(void __user *to, const void *from, unsigned long n)
 		 */
 		  "=&r" (tmp), "+r" (to), "+r" (from)
 		:
-		: "lp_count", "lp_start", "lp_end", "memory");
+		: "lp_count", "memory");
 
 		return n;
 	}
@@ -653,7 +653,7 @@ static inline unsigned long __arc_clear_user(void __user *to, unsigned long n)
 	"	.previous			\n"
 	: "+r"(d_char), "+r"(res)
 	: "i"(0)
-	: "lp_count", "lp_start", "lp_end", "memory");
+	: "lp_count", "memory");
 
 	return res;
 }
@@ -686,7 +686,7 @@ __arc_strncpy_from_user(char *dst, const char __user *src, long count)
 	"	.previous			\n"
 	: "+r"(res), "+r"(dst), "+r"(src), "=r"(val)
 	: "g"(-EFAULT), "r"(count)
-	: "lp_count", "lp_start", "lp_end", "memory");
+	: "lp_count", "memory");
 
 	return res;
 }

arch/arc/kernel/entry-arcv2.S

@@ -209,7 +209,9 @@ restore_regs:
 ;####### Return from Intr #######
 
 debug_marker_l1:
-	bbit1.nt r0, STATUS_DE_BIT, .Lintr_ret_to_delay_slot
+	; 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)

arch/arc/kernel/head.S

@@ -17,6 +17,7 @@
 #include <asm/entry.h>
 #include <asm/arcregs.h>
 #include <asm/cache.h>
+#include <asm/irqflags.h>
 
 .macro CPU_EARLY_SETUP
 
@@ -47,6 +48,15 @@
 	sr	r5, [ARC_REG_DC_CTRL]
 
 1:
+
+#ifdef CONFIG_ISA_ARCV2
+	; Unaligned access is disabled at reset, so re-enable early as
+	; gcc 7.3.1 (ARC GNU 2018.03) onwards generates unaligned access
+	; by default
+	lr	r5, [status32]
+	bset	r5, r5, STATUS_AD_BIT
+	kflag	r5
+#endif
 .endm
 
 	.section .init.text, "ax",@progbits
@@ -90,15 +100,13 @@ ENTRY(stext)
 	st.ab   0, [r5, 4]
 1:
 
-#ifdef CONFIG_ARC_UBOOT_SUPPORT
 	; Uboot - kernel ABI
 	;    r0 = [0] No uboot interaction, [1] cmdline in r2, [2] DTB in r2
-	;    r1 = magic number (board identity, unused as of now
+	;    r1 = magic number (always zero as of now)
 	;    r2 = pointer to uboot provided cmdline or external DTB in mem
-	; These are handled later in setup_arch()
+	; These are handled later in handle_uboot_args()
 	st	r0, [@uboot_tag]
 	st	r2, [@uboot_arg]
-#endif
 
 	; setup "current" tsk and optionally cache it in dedicated r25
 	mov	r9, @init_task

arch/arc/kernel/intc-arcv2.c

@@ -49,11 +49,13 @@ void arc_init_IRQ(void)
 
 	*(unsigned int *)&ictrl = 0;
 
+#ifndef CONFIG_ARC_IRQ_NO_AUTOSAVE
 	ictrl.save_nr_gpr_pairs = 6;	/* r0 to r11 (r12 saved manually) */
 	ictrl.save_blink = 1;
 	ictrl.save_lp_regs = 1;		/* LP_COUNT, LP_START, LP_END */
 	ictrl.save_u_to_u = 0;		/* user ctxt saved on kernel stack */
 	ictrl.save_idx_regs = 1;	/* JLI, LDI, EI */
+#endif
 
 	WRITE_AUX(AUX_IRQ_CTRL, ictrl);