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.

1 files changed, 0 insertions, 34 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;
-}