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Backport r7043 from upstream: partially replaces use of SWP with LDREX/STREX
on systems where SWP is no longer available. This fix is incomplete,
but sufficient for our purposes.
Fri Mar 11 14:51:54 GMT 2016 Lee Noar <leenoar@sky.com>
* sys/_cpucaps.s: New file. Provide functions to probe the
OS for details of the CPU (currently SWP, LDREX/STREX
availability).
* Makefile.am: Add above file.
* include/unixlib/local.h: Add declarations for user facing
functions provided above.
* incl-local/internal/asm_dec.s(__ul_global): Add entry to
record CPU flags.
* incl-local/internal/unix.h: Likewise.
* pthread/_ints.s(__pthread_disable_ints,__pthread_protect_unsafe):
Use CPU flags to determine whether to use the SWP instruction or
LRDEX/STREX.
* sys/_syslib.s(__main): Add call to __probe_cpu_caps.
(__unixlib_fatal): Use CPU flags to determine whether to use the
SWP instruction or LRDEX/STREX.
Index: gcc4/recipe/files/gcc/libunixlib/pthread/_ints.s
===================================================================
--- gcc4/recipe/files/gcc/libunixlib/pthread/_ints.s (revision 7042)
+++ gcc4/recipe/files/gcc/libunixlib/pthread/_ints.s (revision 7043)
@@ -2,7 +2,7 @@
@ disable_ints can be called multiple times, provided enable_ints is
@ subsequently called an equal number of times
@ Written by Martin Piper and Alex Waugh
-@ Copyright (c) 2002-2008 UnixLib Developers
+@ Copyright (c) 2002-2016 UnixLib Developers
#include "internal/asm_dec.s"
@@ -20,15 +20,26 @@
PICEQ "LDR a2, [a2, #0]"
PICEQ "LDR a2, [a2, #__GOTT_INDEX__]" @ a2 = GOT ptr
- LDR a1, .L0 @=__ul_global
+ LDR a1, .L0 @ =__ul_global
PICEQ "LDR a1, [a2, a1]"
+ LDR a4, [a1, #GBL_CPU_FLAGS]
ADD a1, a1, #GBL_PTH_WORKSEMAPHORE
+ TST a4, #__CPUCAP_HAVE_SWP
+ @ From this point onwards we will not be interrupted by the callback
+ BEQ 0f
+
MOV a3, #1
SWP a2, a3, [a1]
- @ From this point onwards we will not be interrupted by the callback
ADD a2, a2, #1
STR a2, [a1]
MOV pc, lr
+0:
+ LDREX a2, [a1]
+ ADD a2, a2, #1
+ STREX a3, a2, [a1]
+ TEQ a3, #1
+ BEQ 0b
+ MOV pc, lr
.L0:
WORD __ul_global
DECLARE_FUNCTION __pthread_disable_ints
@@ -78,18 +89,32 @@
PICEQ "LDR a1, [a1, #0]"
PICEQ "LDR a1, [a1, #__GOTT_INDEX__]" @ a1 = GOT ptr
- LDR a4, .L2 @=__ul_global
+ LDR a4, .L2 @ =__ul_global
PICEQ "LDR a4, [a1, a4]"
+ LDR a2, [a4, #GBL_CPU_FLAGS]
ADD a1, a4, #GBL_PTH_WORKSEMAPHORE
+ TST a2, #__CPUCAP_HAVE_SWP
+ @ From this point onwards we cannot be interrupted by the callback
+ BEQ 0f
+
MOV a2, #1
SWP a3, a2, [a1]
- @ From this point onwards we cannot be interrupted by the callback
CMP a3, #0
- STRNE a3, [a1, #0] @ Restore original value
+ BEQ 1f
+ STR a3, [a1, #0] @ Restore original value
@ Return, as if ints are disabled on entry to the
@ calling function then they should not be reenabled
@ until the calling function has returned
+ MOV pc, lr
+0:
+ LDREX a3, [a1]
+ MOV ip, #1
+ STREX a2, ip, [a1]
+ TEQ a2, #1
+ BEQ 0b
+ TEQ a3, #0
MOVNE pc, lr
+1:
#if __UNIXLIB_PARANOID
LDR a3, [a4, #GBL_PTH_RETURN_ADDRESS]
Index: gcc4/recipe/files/gcc/libunixlib/include/unixlib/local.h
===================================================================
--- gcc4/recipe/files/gcc/libunixlib/include/unixlib/local.h (revision 7042)
+++ gcc4/recipe/files/gcc/libunixlib/include/unixlib/local.h (revision 7043)
@@ -133,6 +133,16 @@
socket. Is -1 when socket handle is not valid. */
extern int __get_ro_socket (int __sockfd);
+/* Return 1 if the SWP instruction is available, otherwise 0. */
+extern unsigned int __cpucap_have_swp (void);
+
+/* Return 1 if the LDREX/STREX instructions are available, otherwise 0. */
+extern unsigned int __cpucap_have_rex (void);
+
+/* Return 1 if the LDREX/STREX instructions that operate on bytes, half-words
+ and double words are available, otherwise 0. */
+extern unsigned int __cpucap_have_rexbhd (void);
+
__END_DECLS
#endif
* incl-local/internal/asm_dec.s(XSOM_DeregisterClient): Add
Index: gcc4/recipe/files/gcc/libunixlib/Makefile.am
===================================================================
--- gcc4/recipe/files/gcc/libunixlib/Makefile.am (revision 7042)
+++ gcc4/recipe/files/gcc/libunixlib/Makefile.am (revision 7043)
@@ -1027,6 +1027,7 @@
sys/sigsetjmp.c \
sys/stackalloc.c \
sys/vfork.c \
+ sys/_cpucaps.s \
sys/_getcpuarch.s \
sys/_jmp.s \
sys/_mman.s \
Index: gcc4/recipe/files/gcc/libunixlib/incl-local/internal/asm_dec.s
===================================================================
--- gcc4/recipe/files/gcc/libunixlib/incl-local/internal/asm_dec.s (revision 7042)
+++ gcc4/recipe/files/gcc/libunixlib/incl-local/internal/asm_dec.s (revision 7043)
@@ -269,8 +269,10 @@
.set GBL_FLS_LBSTM_ON_RD, 108 @ = __ul_global.fls_lbstm_on_rd
.set GBL_PTH_CALLEVERY_RMA, 112 @ = __ul_global.pthread_callevery_rma
+.set GBL_CPU_FLAGS, 116 @ = __ul_global.cpu_flags
+
#if !defined(__SOFTFP__) && defined(__VFP_FP__)
-.set GBL_VFP_REGCOUNT, 116 @ = __ul_global.vfp_regcount
+.set GBL_VFP_REGCOUNT, 120 @ = __ul_global.vfp_regcount
#endif
@ Entries in the __ul_memory table. Must be kept in sync with
@@ -322,3 +324,7 @@
.set CRT1_LIB_FINI, 32 @ Ptr to function to finalise shared libraries
@ at program exit - can be NULL.
#endif
+
+#define __CPUCAP_HAVE_SWP 0x1
+#define __CPUCAP_HAVE_REX 0x2
+#define __CPUCAP_HAVE_REXBHD 0x4
Index: gcc4/recipe/files/gcc/libunixlib/incl-local/internal/unix.h
===================================================================
--- gcc4/recipe/files/gcc/libunixlib/incl-local/internal/unix.h (revision 7042)
+++ gcc4/recipe/files/gcc/libunixlib/incl-local/internal/unix.h (revision 7043)
@@ -197,6 +197,8 @@
the life of the program. This block is passed to the call_every handler in
r12. */
+ unsigned int cpu_flags; /* Flags indicating the capabilities of the CPU. */
+
#if !defined(__SOFTFP__) && defined(__VFP_FP__)
int vfp_regcount; /* Number of doubleword registers we should request for
VFP contexts */
Index: gcc4/recipe/files/gcc/libunixlib/sys/_cpucaps.s
===================================================================
--- gcc4/recipe/files/gcc/libunixlib/sys/_cpucaps.s (revision 0)
+++ gcc4/recipe/files/gcc/libunixlib/sys/_cpucaps.s (revision 7043)
@@ -0,0 +1,91 @@
+@ Determine the capabilities of the CPU and allow callers to enquire
+@ what they are.
+@ Copyright (c) 2016 UnixLib Developers.
+@ Written by Lee Noar.
+
+#include "internal/asm_dec.s"
+
+ .text
+
+@ Determine what the CPU capabilities are, and record them.
+@ Called early on during program initialisation in _syslib.s.
+ .global __probe_cpu_caps
+ NAME __probe_cpu_caps
+__probe_cpu_caps:
+ MOV r0, #0
+ SWI XOS_PlatformFeatures
+ MOVVS r0, #0
+
+ MOV r2, #0
+ @ The OS flag is set to 1 to indicate _no_ SWP instruction available (for
+ @ backwards compatibility). We reverse it here and set our flag to 1 to
+ @ indicate that SWP _is_ available.
+ TST r0, #1<<11 @ SWP{B} not available
+ ORREQ r2, r2, #__CPUCAP_HAVE_SWP
+ TST r0, #1<<12 @ LDREX/STREX available
+ ORRNE r2, r2, #__CPUCAP_HAVE_REX
+ TST r0, #1<<13 @ LDREX/STREX{B/H/D} available
+ ORRNE r2, r2, #__CPUCAP_HAVE_REXBHD
+
+ PICEQ "LDR r0, =__GOTT_BASE__"
+ PICEQ "LDR r0, [r0, #0]"
+ PICEQ "LDR r0, [r0, #__GOTT_INDEX__]" @ r0 = GOT ptr
+ LDR r1, .L0 @ =__ul_global
+ PICEQ "LDR r1, [r0, r1]"
+ STR r2, [r1, #GBL_CPU_FLAGS]
+
+ MOV pc, lr
+.L0:
+ WORD __ul_global
+ DECLARE_FUNCTION __probe_cpu_caps
+
+ .global __cpucap_have_swp
+ NAME __cpucap_have_swp
+__cpucap_have_swp:
+ PICEQ "LDR r0, =__GOTT_BASE__"
+ PICEQ "LDR r0, [r0, #0]"
+ PICEQ "LDR r0, [r0, #__GOTT_INDEX__]" @ r0 = GOT ptr
+ LDR r1, .L0 @ =__ul_global
+ PICEQ "LDR r1, [r0, r1]"
+ LDR r0, [r1, #GBL_CPU_FLAGS]
+ TST r0, #__CPUCAP_HAVE_SWP
+ MOVEQ r0, #0
+ MOVNE r0, #1
+
+ MOV pc, lr
+ DECLARE_FUNCTION __cpucap_have_swp
+
+@ Return 1 if LDREX/STREX instructions are available on the CPU, otherwise 0.
+ .global __cpucap_have_rex
+ NAME __cpucap_have_rex
+__cpucap_have_rex:
+ PICEQ "LDR r0, =__GOTT_BASE__"
+ PICEQ "LDR r0, [r0, #0]"
+ PICEQ "LDR r0, [r0, #__GOTT_INDEX__]" @ r0 = GOT ptr
+ LDR r1, .L0 @ =__ul_global
+ PICEQ "LDR r1, [r0, r1]"
+ LDR r0, [r1, #GBL_CPU_FLAGS]
+ TST r0, #__CPUCAP_HAVE_REX
+ MOVEQ r0, #0
+ MOVNE r0, #1
+
+ MOV pc, lr
+ DECLARE_FUNCTION __cpucap_have_rex
+
+@ Return 1 if LDREX/STREX instructions that work on non-32 bit data sizes
+@ are available on the CPU, otherwise 0.
+ .global __cpucap_have_rexbhd
+ NAME __cpucap_have_rexbhd
+__cpucap_have_rexbhd:
+ PICEQ "LDR r0, =__GOTT_BASE__"
+ PICEQ "LDR r0, [r0, #0]"
+ PICEQ "LDR r0, [r0, #__GOTT_INDEX__]" @ r0 = GOT ptr
+ LDR r1, .L0 @ =__ul_global
+ PICEQ "LDR r1, [r0, r1]"
+ LDR r0, [r1, #GBL_CPU_FLAGS]
+ TST r0, #__CPUCAP_HAVE_REXBHD
+ MOVEQ r0, #0
+ MOVNE r0, #1
+
+ MOV pc, lr
+ DECLARE_FUNCTION __cpucap_have_rexbhd
Index: gcc4/recipe/files/gcc/libunixlib/sys/_syslib.s
===================================================================
--- gcc4/recipe/files/gcc/libunixlib/sys/_syslib.s (revision 7042)
+++ gcc4/recipe/files/gcc/libunixlib/sys/_syslib.s (revision 7043)
@@ -255,6 +255,8 @@
BCC __exit_with_error_num
unknown_cpu_arch:
+ BL __probe_cpu_caps
+
@ Use of DAs explicitly overridden if __dynamic_no_da is declared
MOV lr, #-1
STR lr, [ip, #GBL_DYNAMIC_NUM]
@@ -1286,9 +1288,21 @@
@ error handling. As last resort to avoid an infinite loop
@ we go for a straight OS_Exit scenario. Anything better we
@ can do ?
+ ADD a3, a4, #GBL_PANIC_MODE
+ LDR a2, [a4, #GBL_CPU_FLAGS]
+ TST a2, #__CPUCAP_HAVE_SWP
+ BEQ 0f
+
MOV a2, #1
- ADD a3, a4, #GBL_PANIC_MODE
SWP a2, a2, [a3]
+ B 1f
+0:
+ LDREX a2, [a3]
+ MOV ip, #1
+ STREX lr, ip, [a3]
+ TEQ lr, #1
+ BEQ 0b
+1:
TEQ a2, #0
BEQ __unixlib_fatal_cont1
|
