[Blackfin] arch: a rather old performance improvement for the signal handling code
This is a rather old performance improvement for the signal handling
code, which was originally only committed on the 2007R1 branch as a
workaround for what we suspected to be a hardware bug.
There's no point in constructing a sigreturn stub on the stack and
flushing caches; we can just make signal handlers return to a known
location in the fixed code area.
Signed-off-by: Bernd Schmidt <bernds_cb1@t-online.de>
Signed-off-by: Bryan Wu <cooloney@kernel.org>
diff --git a/arch/blackfin/kernel/signal.c b/arch/blackfin/kernel/signal.c
index 71cfcd2..d1fa244 100644
--- a/arch/blackfin/kernel/signal.c
+++ b/arch/blackfin/kernel/signal.c
@@ -38,6 +38,7 @@
#include <asm/cacheflush.h>
#include <asm/ucontext.h>
+#include <asm/fixed_code.h>
#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
@@ -50,6 +51,8 @@
int sig;
struct siginfo *pinfo;
void *puc;
+ /* This is no longer needed by the kernel, but unfortunately userspace
+ * code expects it to be there. */
char retcode[8];
struct siginfo info;
struct ucontext uc;
@@ -159,11 +162,6 @@
return err;
}
-static inline void push_cache(unsigned long vaddr, unsigned int len)
-{
- flush_icache_range(vaddr, vaddr + len);
-}
-
static inline void *get_sigframe(struct k_sigaction *ka, struct pt_regs *regs,
size_t frame_size)
{
@@ -209,19 +207,9 @@
err |= rt_setup_sigcontext(&frame->uc.uc_mcontext, regs);
err |= copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
- /* Set up to return from userspace. */
- err |= __put_user(0x28, &(frame->retcode[0]));
- err |= __put_user(0xe1, &(frame->retcode[1]));
- err |= __put_user(0xad, &(frame->retcode[2]));
- err |= __put_user(0x00, &(frame->retcode[3]));
- err |= __put_user(0xa0, &(frame->retcode[4]));
- err |= __put_user(0x00, &(frame->retcode[5]));
-
if (err)
goto give_sigsegv;
- push_cache((unsigned long)&frame->retcode, sizeof(frame->retcode));
-
/* Set up registers for signal handler */
wrusp((unsigned long)frame);
if (get_personality & FDPIC_FUNCPTRS) {
@@ -231,7 +219,7 @@
__get_user(regs->p3, &funcptr->GOT);
} else
regs->pc = (unsigned long)ka->sa.sa_handler;
- regs->rets = (unsigned long)(frame->retcode);
+ regs->rets = SIGRETURN_STUB;
regs->r0 = frame->sig;
regs->r1 = (unsigned long)(&frame->info);