Commit 697a9d65 authored by Bernd Schmidt's avatar Bernd Schmidt Committed by Bryan Wu
Browse files

[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: default avatarBernd Schmidt <bernds_cb1@t-online.de>
Signed-off-by: default avatarBryan Wu <cooloney@kernel.org>
parent 5af29f59

arch/blackfin/kernel/signal.c

+4 −16
Original line number Diff line number Diff line
@@ -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 @@ struct rt_sigframe { 
	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 @@ static inline int rt_setup_sigcontext(struct sigcontext *sc, struct pt_regs *reg 
	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 @@ setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t * info, 
	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 @@ setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t * info, 
		__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);

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