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Blackfin arch: defines and provides entry points for certain user space functions at fixed addresses

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This patch defines (and provides) entry points for certain user space functions
at fixed addresses.  The Blackfin has no usable atomic instructions, but we can
ensure that these code sequences appear atomic from a user space point of view
by detecting when we're in the process of executing them during the interrupt
handler return path.  This allows much more efficient pthread lock
implementations than the bfin_spinlock syscall we're currently using.

Also provided is a small sys_rt_sigreturn stub which can be used by the signal
handler setup code.  The signal.c part will be committed separately.

Signed-off-by: Bernd Schmidt <bernd.schmidt@analog.com>
Signed-off-by: Bryan Wu <bryan.wu@analog.com>
This commit is contained in:
Bernd Schmidt
2007-06-21 11:34:16 +08:00
committed by Bryan Wu
parent 0ba9e350a2
commit 7adfb58fbd
9 changed files with 261 additions and 3 deletions
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22
arch/blackfin/kernel/setup.c
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@@ -42,6 +42,7 @@
#include <asm/cacheflush.h>
#include <asm/blackfin.h>
#include <asm/cplbinit.h>
#include <asm/fixed_code.h>
u16 _bfin_swrst;
@@ -404,6 +405,27 @@ void __init setup_arch(char **cmdline_p)
printk(KERN_INFO "Hardware Trace Enabled\n");
bfin_write_TBUFCTL(0x03);
/* Copy atomic sequences to their fixed location, and sanity check that
these locations are the ones that we advertise to userspace. */
memcpy((void *)FIXED_CODE_START, &fixed_code_start,
FIXED_CODE_END - FIXED_CODE_START);
BUG_ON((char *)&sigreturn_stub - (char *)&fixed_code_start
!= SIGRETURN_STUB - FIXED_CODE_START);
BUG_ON((char *)&atomic_xchg32 - (char *)&fixed_code_start
!= ATOMIC_XCHG32 - FIXED_CODE_START);
BUG_ON((char *)&atomic_cas32 - (char *)&fixed_code_start
!= ATOMIC_CAS32 - FIXED_CODE_START);
BUG_ON((char *)&atomic_add32 - (char *)&fixed_code_start
!= ATOMIC_ADD32 - FIXED_CODE_START);
BUG_ON((char *)&atomic_sub32 - (char *)&fixed_code_start
!= ATOMIC_SUB32 - FIXED_CODE_START);
BUG_ON((char *)&atomic_ior32 - (char *)&fixed_code_start
!= ATOMIC_IOR32 - FIXED_CODE_START);
BUG_ON((char *)&atomic_and32 - (char *)&fixed_code_start
!= ATOMIC_AND32 - FIXED_CODE_START);
BUG_ON((char *)&atomic_xor32 - (char *)&fixed_code_start
!= ATOMIC_XOR32 - FIXED_CODE_START);
}
static int __init topology_init(void)