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authorRich Felker <dalias@aerifal.cx>2016-01-21 19:28:15 +0000
committerRich Felker <dalias@aerifal.cx>2016-01-21 19:43:04 +0000
commit61b1e75f7d8004461f2e18f171c26c2f545eed32 (patch)
tree7a88f8d51ee3f049745b147b7f36fc8ee22e0e62 /src
parent1315596b510189b5159e742110b504177bdd4932 (diff)
downloadmusl-61b1e75f7d8004461f2e18f171c26c2f545eed32.tar.gz
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.
Diffstat (limited to 'src')
-rw-r--r--src/thread/sh/__set_thread_area.c40
-rw-r--r--src/thread/sh/__set_thread_area.s0
-rw-r--r--src/thread/sh/atomics.s65
3 files changed, 105 insertions, 0 deletions
diff --git a/src/thread/sh/__set_thread_area.c b/src/thread/sh/__set_thread_area.c
new file mode 100644
index 00000000..9c47f78d
--- /dev/null
+++ b/src/thread/sh/__set_thread_area.c
@@ -0,0 +1,40 @@
+#include "pthread_impl.h"
+#include "libc.h"
+#include <elf.h>
+
+/* Also perform sh-specific init */
+
+#define CPU_HAS_LLSC 0x0040
+#define CPU_HAS_CAS_L 0x0400
+
+__attribute__((__visibility__("hidden")))
+extern const char __sh_cas_gusa[], __sh_cas_llsc[], __sh_cas_imask[], __sh_cas_cas_l[];
+
+__attribute__((__visibility__("hidden")))
+const void *__sh_cas_ptr;
+
+__attribute__((__visibility__("hidden")))
+unsigned __sh_nommu;
+
+int __set_thread_area(void *p)
+{
+ size_t *aux;
+ __asm__ __volatile__ ( "ldc %0, gbr" : : "r"(p) : "memory" );
+#ifndef __SH4A__
+ __sh_cas_ptr = __sh_cas_gusa;
+#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_cas_ptr = __sh_cas_imask;
+ __sh_nommu = 1;
+ }
+#endif
+ if (__hwcap & CPU_HAS_CAS_L)
+ __sh_cas_ptr = __sh_cas_cas_l;
+ else if (__hwcap & CPU_HAS_LLSC)
+ __sh_cas_ptr = __sh_cas_llsc;
+#endif
+ return 0;
+}
diff --git a/src/thread/sh/__set_thread_area.s b/src/thread/sh/__set_thread_area.s
deleted file mode 100644
index e69de29b..00000000
--- a/src/thread/sh/__set_thread_area.s
+++ /dev/null
diff --git a/src/thread/sh/atomics.s b/src/thread/sh/atomics.s
new file mode 100644
index 00000000..3b58cccc
--- /dev/null
+++ b/src/thread/sh/atomics.s
@@ -0,0 +1,65 @@
+/* Contract for all versions is same as cas.l r2,r3,@r0
+ * pr and r1 are also clobbered (by jsr & r1 as temp).
+ * r0,r2,r4-r15 must be preserved.
+ * r3 contains result (==r2 iff cas succeeded). */
+
+ .align 2
+.global __sh_cas_gusa
+.hidden __sh_cas_gusa
+__sh_cas_gusa:
+ mov.l r5,@-r15
+ mov.l r4,@-r15
+ mov r0,r4
+ mova 1f,r0
+ mov r15,r1
+ mov #(0f-1f),r15
+0: mov.l @r4,r5
+ cmp/eq r5,r2
+ bf 1f
+ mov.l r3,@r4
+1: mov r1,r15
+ mov r5,r3
+ mov r4,r0
+ mov.l @r15+,r4
+ rts
+ mov.l @r15+,r5
+
+.global __sh_cas_llsc
+.hidden __sh_cas_llsc
+__sh_cas_llsc:
+ mov r0,r1
+ synco
+0: movli.l @r1,r0
+ cmp/eq r0,r2
+ bf 1f
+ mov r3,r0
+ movco.l r0,@r1
+ bf 0b
+ mov r2,r0
+1: synco
+ mov r0,r3
+ rts
+ mov r1,r0
+
+.global __sh_cas_imask
+.hidden __sh_cas_imask
+__sh_cas_imask:
+ mov r0,r1
+ stc sr,r0
+ mov.l r0,@-r15
+ or #0xf0,r0
+ ldc r0,sr
+ mov.l @r1,r0
+ cmp/eq r0,r2
+ bf 1f
+ mov.l r3,@r1
+1: ldc.l @r15+,sr
+ mov r0,r3
+ rts
+ mov r1,r0
+
+.global __sh_cas_cas_l
+.hidden __sh_cas_cas_l
+__sh_cas_cas_l:
+ rts
+ .word 0x2323 /* cas.l r2,r3,@r0 */