overhaul sh atomics for new atomics framework, add j-core cas.l backend

sh needs runtime-selected atomic backends since there are a number of
supported models that use non-forwards-compatible (non-smp-compatible)
atomic mechanisms. previously, the code paths for this were highly
inefficient since they involved C function calls with multiple
branches in the callee and heavy spills in the caller. the new code
performs calls the runtime-selected asm fragment from inline asm with
extremely minimal clobbers, rather than using a function call.

for the sh4a case where the atomic mechanism is known and there is no
forward-compatibility issue, the movli.l and movco.l instructions are
provided as a_ll and a_sc, allowing the new shared atomic.h to
generate efficient inline versions of all the basic atomic operations
without needing a cas loop.

3 files changed, 0 insertions, 207 deletions

diff --git a/arch/sh/src/__set_thread_area.c b/arch/sh/src/__set_thread_area.c
deleted file mode 100644
index 1d3e0225..00000000
--- a/arch/sh/src/__set_thread_area.c
+++ /dev/null
@@ -1,34 +0,0 @@
-#include "pthread_impl.h"
-#include "libc.h"
-#include "sh_atomic.h"
-#include <elf.h>
-
-/* Also perform sh-specific init */
-
-#define CPU_HAS_LLSC 0x0040
-
-__attribute__((__visibility__("hidden"))) unsigned __sh_atomic_model, __sh_nommu;
-
-int __set_thread_area(void *p)
-{
-	size_t *aux;
-	__asm__ __volatile__ ( "ldc %0, gbr" : : "r"(p) : "memory" );
-#ifndef __SH4A__
-	if (__hwcap & CPU_HAS_LLSC) {
-		__sh_atomic_model = SH_A_LLSC;
-		return 0;
-	}
-#if !defined(__SH3__) && !defined(__SH4__)
-	for (aux=libc.auxv; *aux; aux+=2) {
-		if (*aux != AT_PLATFORM) continue;
-		const char *s = (void *)aux[1];
-		if (s[0]!='s' || s[1]!='h' || s[2]!='2' || s[3]-'0'<10u) break;
-		__sh_atomic_model = SH_A_IMASK;
-		__sh_nommu = 1;
-		return 0;
-	}
-#endif
-	/* __sh_atomic_model = SH_A_GUSA; */ /* 0, default */
-#endif
-	return 0;
-}
diff --git a/arch/sh/src/atomic.c b/arch/sh/src/atomic.c
deleted file mode 100644
index 7fd73074..00000000
--- a/arch/sh/src/atomic.c
+++ /dev/null
@@ -1,158 +0,0 @@
-#ifndef __SH4A__
-
-#include "sh_atomic.h"
-#include "atomic.h"
-#include "libc.h"
-
-static inline unsigned mask()
-{
-	unsigned sr;
-	__asm__ __volatile__ ( "\n"
-	"	stc sr,r0 \n"
-	"	mov r0,%0 \n"
-	"	or #0xf0,r0 \n"
-	"	ldc r0,sr \n"
-	: "=&r"(sr) : : "memory", "r0" );
-	return sr;
-}
-
-static inline void unmask(unsigned sr)
-{
-	__asm__ __volatile__ ( "ldc %0,sr" : : "r"(sr) : "memory" );
-}
-
-/* gusa is a hack in the kernel which lets you create a sequence of instructions
- * which will be restarted if the process is preempted in the middle of the
- * sequence. It will do for implementing atomics on non-smp systems. ABI is:
- * r0  = address of first instruction after the atomic sequence
- * r1  = original stack pointer
- * r15 = -1 * length of atomic sequence in bytes
- */
-#define GUSA_CLOBBERS   "r0", "r1", "memory"
-#define GUSA_START(mem,old,nop)    \
-	"	.align 2\n"                \
-	"	mova 1f, r0\n"             \
-	nop                            \
-	"	mov r15, r1\n"             \
-	"	mov #(0f-1f), r15\n"       \
-	"0:	mov.l @" mem ", " old "\n"
-/* the target of mova must be 4 byte aligned, so we may need a nop */
-#define GUSA_START_ODD(mem,old)  GUSA_START(mem,old,"")
-#define GUSA_START_EVEN(mem,old) GUSA_START(mem,old,"\tnop\n")
-#define GUSA_END(mem,new)          \
-	"	mov.l " new ", @" mem "\n" \
-	"1:	mov r1, r15\n"
-
-int __sh_cas(volatile int *p, int t, int s)
-{
-	if (__sh_atomic_model == SH_A_LLSC) return __sh_cas_llsc(p, t, s);
-
-	if (__sh_atomic_model == SH_A_IMASK) {
-		unsigned sr = mask();
-		int old = *p;
-		if (old==t) *p = s;
-		unmask(sr);
-		return old;
-	}
-
-	int old;
-	__asm__ __volatile__(
-		GUSA_START_EVEN("%1", "%0")
-		"	cmp/eq %0, %2\n"
-		"	bf 1f\n"
-		GUSA_END("%1", "%3")
-		: "=&r"(old) : "r"(p), "r"(t), "r"(s) : GUSA_CLOBBERS, "t");
-	return old;
-}
-
-int __sh_swap(volatile int *x, int v)
-{
-	if (__sh_atomic_model == SH_A_LLSC) return __sh_swap_llsc(x, v);
-
-	if (__sh_atomic_model == SH_A_IMASK) {
-		unsigned sr = mask();
-		int old = *x;
-		*x = v;
-		unmask(sr);
-		return old;
-	}
-
-	int old;
-	__asm__ __volatile__(
-		GUSA_START_EVEN("%1", "%0")
-		GUSA_END("%1", "%2")
-		: "=&r"(old) : "r"(x), "r"(v) : GUSA_CLOBBERS);
-	return old;
-}
-
-int __sh_fetch_add(volatile int *x, int v)
-{
-	if (__sh_atomic_model == SH_A_LLSC) return __sh_fetch_add_llsc(x, v);
-
-	if (__sh_atomic_model == SH_A_IMASK) {
-		unsigned sr = mask();
-		int old = *x;
-		*x = old + v;
-		unmask(sr);
-		return old;
-	}
-
-	int old, dummy;
-	__asm__ __volatile__(
-		GUSA_START_EVEN("%2", "%0")
-		"	mov %0, %1\n"
-		"	add %3, %1\n"
-		GUSA_END("%2", "%1")
-		: "=&r"(old), "=&r"(dummy) : "r"(x), "r"(v) : GUSA_CLOBBERS);
-	return old;
-}
-
-void __sh_store(volatile int *p, int x)
-{
-	if (__sh_atomic_model == SH_A_LLSC) return __sh_store_llsc(p, x);
-	__asm__ __volatile__(
-		"	mov.l %1, @%0\n"
-		: : "r"(p), "r"(x) : "memory");
-}
-
-void __sh_and(volatile int *x, int v)
-{
-	if (__sh_atomic_model == SH_A_LLSC) return __sh_and_llsc(x, v);
-
-	if (__sh_atomic_model == SH_A_IMASK) {
-		unsigned sr = mask();
-		int old = *x;
-		*x = old & v;
-		unmask(sr);
-		return;
-	}
-
-	int dummy;
-	__asm__ __volatile__(
-		GUSA_START_ODD("%1", "%0")
-		"	and %2, %0\n"
-		GUSA_END("%1", "%0")
-		: "=&r"(dummy) : "r"(x), "r"(v) : GUSA_CLOBBERS);
-}
-
-void __sh_or(volatile int *x, int v)
-{
-	if (__sh_atomic_model == SH_A_LLSC) return __sh_or_llsc(x, v);
-
-	if (__sh_atomic_model == SH_A_IMASK) {
-		unsigned sr = mask();
-		int old = *x;
-		*x = old | v;
-		unmask(sr);
-		return;
-	}
-
-	int dummy;
-	__asm__ __volatile__(
-		GUSA_START_ODD("%1", "%0")
-		"	or %2, %0\n"
-		GUSA_END("%1", "%0")
-		: "=&r"(dummy) : "r"(x), "r"(v) : GUSA_CLOBBERS);
-}
-
-#endif
diff --git a/arch/sh/src/sh_atomic.h b/arch/sh/src/sh_atomic.h
deleted file mode 100644
index 054c2a32..00000000
--- a/arch/sh/src/sh_atomic.h
+++ /dev/null
@@ -1,15 +0,0 @@
-#ifndef _SH_ATOMIC_H
-#define _SH_ATOMIC_H
-
-#define SH_A_GUSA 0
-#define SH_A_LLSC 1
-#define SH_A_CAS 2
-#if !defined(__SH3__) && !defined(__SH4__)
-#define SH_A_IMASK 3
-#else
-#define SH_A_IMASK -1LL /* unmatchable by unsigned int */
-#endif
-
-extern __attribute__((__visibility__("hidden"))) unsigned __sh_atomic_model;
-
-#endif