From 926494943b7d9dbc998adb298a92a708232ce46b Mon Sep 17 00:00:00 2001 From: Mike Frysinger Date: Mon, 17 Aug 2009 19:05:07 +0000 Subject: [PATCH] Blackfin: optimize fixed code handling for the most common case The majority of the time we are returning to user space, it is not in the fixed atomic code region. So rather than branch to a function where we check the PC and return, do the check inline and branch only when needed. Also, tweak some of the fixed code handling based on assumptions we are aware of but cannot be expressed in C. Signed-off-by: Mike Frysinger --- arch/blackfin/kernel/process.c | 10 ++-------- arch/blackfin/mach-common/entry.S | 6 ++++++ 2 files changed, 8 insertions(+), 8 deletions(-) diff --git a/arch/blackfin/kernel/process.c b/arch/blackfin/kernel/process.c index 9da36bab7ccb..f5b286189647 100644 --- a/arch/blackfin/kernel/process.c +++ b/arch/blackfin/kernel/process.c @@ -282,25 +282,19 @@ void finish_atomic_sections (struct pt_regs *regs) { int __user *up0 = (int __user *)regs->p0; - if (regs->pc < ATOMIC_SEQS_START || regs->pc >= ATOMIC_SEQS_END) - return; - switch (regs->pc) { case ATOMIC_XCHG32 + 2: put_user(regs->r1, up0); - regs->pc += 2; + regs->pc = ATOMIC_XCHG32 + 4; break; case ATOMIC_CAS32 + 2: case ATOMIC_CAS32 + 4: if (regs->r0 == regs->r1) + case ATOMIC_CAS32 + 6: put_user(regs->r2, up0); regs->pc = ATOMIC_CAS32 + 8; break; - case ATOMIC_CAS32 + 6: - put_user(regs->r2, up0); - regs->pc += 2; - break; case ATOMIC_ADD32 + 2: regs->r0 = regs->r1 + regs->r0; diff --git a/arch/blackfin/mach-common/entry.S b/arch/blackfin/mach-common/entry.S index e7eb16355f74..a9b15aaf5254 100644 --- a/arch/blackfin/mach-common/entry.S +++ b/arch/blackfin/mach-common/entry.S @@ -1025,6 +1025,12 @@ ENTRY(_schedule_and_signal_from_int) #endif sti r0; + /* finish the userspace "atomic" functions for it */ + r1 = FIXED_CODE_END; + r2 = [sp + PT_PC]; + cc = r1 <= r2; + if cc jump .Lresume_userspace (bp); + r0 = sp; sp += -12; call _finish_atomic_sections;