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86effd0dc6
This uses a new set of annoations viz. ENTRY_CFI/END_CFI to enabel cfi
ops generation.
Note that we didn't change the normal ENTRY/EXIT as we don't actually
want unwind info in the trap/exception/interrutp handlers which use
these, as unwinder then gets confused (it keeps recursing vs. stopping).
Semantically these are leaf routines and unwinding should stop when it
hits those routines.
Before
------
28.52% 1.19% 9929 hackbench libuClibc-1.0.17.so [.] __write_nocancel
|
---__write_nocancel
|--8.95%--EV_Trap
| --8.25%--sys_write
| |--3.93%--sock_write_iter
...
|--2.62%--memset <==== [LEAF entry as no unwind info]
^^^^^^
After
-----
29.46% 1.24% 13622 hackbench libuClibc-1.0.17.so [.] __write_nocancel
|
---__write_nocancel
|--9.31%--EV_Trap
| --8.62%--sys_write
| |--4.17%--sock_write_iter
...
|--6.19%--sys_write
| --6.19%--sock_write_iter
| unix_stream_sendmsg
| |--1.62%--sock_alloc_send_pskb
| |--0.89%--sock_def_readable
| |--0.88%--_raw_spin_unlock_irqrestore
| |--0.69%--memset
| | ^^^^^^ <==== [now in proper callframe]
| |
| --0.52%--skb_copy_datagram_from_iter
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
63 lines
1.7 KiB
ArmAsm
63 lines
1.7 KiB
ArmAsm
/*
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* Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* Vineetg: Aug 2009
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* -Moved core context switch macro out of entry.S into this file.
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* -This is the more "natural" hand written assembler
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*/
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#include <linux/linkage.h>
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#include <asm/entry.h> /* For the SAVE_* macros */
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#include <asm/asm-offsets.h>
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#define KSP_WORD_OFF ((TASK_THREAD + THREAD_KSP) / 4)
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;################### Low Level Context Switch ##########################
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.section .sched.text,"ax",@progbits
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.align 4
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.global __switch_to
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.type __switch_to, @function
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__switch_to:
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CFI_STARTPROC
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/* Save regs on kernel mode stack of task */
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st.a blink, [sp, -4]
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st.a fp, [sp, -4]
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SAVE_CALLEE_SAVED_KERNEL
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/* Save the now KSP in task->thread.ksp */
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#if KSP_WORD_OFF <= 255
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st.as sp, [r0, KSP_WORD_OFF]
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#else
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/* Workaround for NR_CPUS=4k as ST.as can only take s9 offset */
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add2 r24, r0, KSP_WORD_OFF
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st sp, [r24]
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#endif
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/*
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* Return last task in r0 (return reg)
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* On ARC, Return reg = First Arg reg = r0.
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* Since we already have last task in r0,
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* don't need to do anything special to return it
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*/
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/*
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* switch to new task, contained in r1
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* Temp reg r3 is required to get the ptr to store val
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*/
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SET_CURR_TASK_ON_CPU r1, r3
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/* reload SP with kernel mode stack pointer in task->thread.ksp */
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ld.as sp, [r1, (TASK_THREAD + THREAD_KSP)/4]
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/* restore the registers */
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RESTORE_CALLEE_SAVED_KERNEL
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ld.ab fp, [sp, 4]
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ld.ab blink, [sp, 4]
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j [blink]
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END_CFI(__switch_to)
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