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From a5b566da301f670302930a0af4a8102a29d27f7f Mon Sep 17 00:00:00 2001
From: Wu Zhangjin <wuzhangjin@gmail.com>
Date: Wed, 20 Oct 2010 02:27:26 +0800
Subject: [PATCH 7/9] MIPS: tracing/ftrace: Fixes mcount_regex for modules
In some situations, the modules may have the same address space as the
core kernel space, then, it should also match the regular R_MIPS_26
string.
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
---
scripts/recordmcount.pl | 46 +++++++++++++++++++++++++++++-----------------
1 file changed, 29 insertions(+), 17 deletions(-)
diff --git a/scripts/recordmcount.pl b/scripts/recordmcount.pl
index 826470d..9e6dc30 100755
--- a/scripts/recordmcount.pl
+++ b/scripts/recordmcount.pl
@@ -310,14 +310,33 @@ if ($arch eq "x86_64") {
$cc .= " -m64";
$objcopy .= " -O elf64-sparc";
} elsif ($arch eq "mips") {
- # To enable module support, we need to enable the -mlong-calls option
- # of gcc for module, after using this option, we can not get the real
- # offset of the calling to _mcount, but the offset of the lui
- # instruction or the addiu one. herein, we record the address of the
- # first one, and then we can replace this instruction by a branch
- # instruction to jump over the profiling function to filter the
- # indicated functions, or swith back to the lui instruction to trace
- # them, which means dynamic tracing.
+ # <For kernel>
+ # To disable tracing, just replace "jal _mcount" with nop;
+ # to enable tracing, replace back. so, the offset 14 is
+ # needed to be recorded.
+ #
+ # 10: 03e0082d move at,ra
+ # 14: 0c000000 jal 0
+ # 14: R_MIPS_26 _mcount
+ # 14: R_MIPS_NONE *ABS*
+ # 14: R_MIPS_NONE *ABS*
+ # 18: 00020021 nop
+ #
+ # <For module>
+ #
+ # If no long call(-mlong-calls), the same to kernel.
+ #
+ # If the module space differs from the kernel space, long
+ # call is needed, as a result, the address of _mcount is
+ # needed to be recorded in a register and then jump from
+ # module space to kernel space via "jalr <register>". To
+ # disable tracing, "jalr <register>" can be replaced by
+ # nop; to enable tracing, replace it back. Since the
+ # offset of "jalr <register>" is not easy to be matched,
+ # the offset of the 1st _mcount below is recorded and to
+ # disable tracing, "lui v1, 0x0" is substituted with "b
+ # label", which jumps over "jalr <register>"; to enable
+ # tracing, replace it back.
#
# c: 3c030000 lui v1,0x0
# c: R_MIPS_HI16 _mcount
@@ -329,19 +348,12 @@ if ($arch eq "x86_64") {
# 10: R_MIPS_NONE *ABS*
# 14: 03e0082d move at,ra
# 18: 0060f809 jalr v1
+ # label:
#
- # for the kernel:
- #
- # 10: 03e0082d move at,ra
- # 14: 0c000000 jal 0 <loongson_halt>
- # 14: R_MIPS_26 _mcount
- # 14: R_MIPS_NONE *ABS*
- # 14: R_MIPS_NONE *ABS*
- # 18: 00020021 nop
if ($is_module eq "0") {
$mcount_regex = "^\\s*([0-9a-fA-F]+): R_MIPS_26\\s+_mcount\$";
} else {
- $mcount_regex = "^\\s*([0-9a-fA-F]+): R_MIPS_HI16\\s+_mcount\$";
+ $mcount_regex = "^\\s*([0-9a-fA-F]+): R_MIPS_(HI16|26)\\s+_mcount\$";
}
$objdump .= " -Melf-trad".$endian."mips ";
--
2.4.3
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