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ARC: dw2 unwind: enable cfi pseudo ops in string lib

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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>
This commit is contained in:
Vineet Gupta
2016-09-19 16:42:25 -07:00
parent 5a205a32ff
commit 86effd0dc6
11 changed files with 26 additions and 25 deletions
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4
arch/arc/lib/strcmp-archs.S
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@@ -8,7 +8,7 @@
#include <linux/linkage.h>
ENTRY(strcmp)
ENTRY_CFI(strcmp)
or r2, r0, r1
bmsk_s r2, r2, 1
brne r2, 0, @.Lcharloop
@@ -75,4 +75,4 @@ ENTRY(strcmp)
.Lcmpend:
j_s.d [blink]
sub r0, r2, r3
END(strcmp)
END_CFI(strcmp)