path: root/scripts/Makefile.build
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authorSteven Rostedt <srostedt@redhat.com>2010-10-15 11:49:47 -0400
committerSteven Rostedt <rostedt@goodmis.org>2010-10-15 11:49:47 -0400
commit444758636439810f110f86a3042c2dfd3626a9e2 (patch)
tree5aa9ff2f34daa5d1bf0f2bd7134d011b38303e19 /scripts/Makefile.build
parentcf4db2597ae93b60efc0a7a4ec08690b75d629b1 (diff)
ftrace: Do not process kernel/trace/ftrace.o with C recordmcount program
The file kernel/trace/ftrace.c references the mcount() call to convert the mcount() callers to nops. But because it references mcount(), the mcount() address is placed in the relocation table. The C version of recordmcount reads the relocation table of all object files, and it will add all references to mcount to the __mcount_loc table that is used to find the places that call mcount() and change the call to a nop. When recordmcount finds the mcount reference in kernel/trace/ftrace.o, it saves that location even though the code is not a call, but references mcount as data. On boot up, when all calls are converted to nops, the code has a safety check to determine what op code it is actually replacing before it replaces it. If that op code at the address does not match, then a warning is printed and the function tracer is disabled. The reference to mcount in ftrace.c, causes this warning to trigger, since the reference is not a call to mcount(). The ftrace.c file is not compiled with the -pg flag, so no calls to mcount() should be expected. This patch simply makes recordmcount.c skip the kernel/trace/ftrace.c file. This was the same solution used by the perl version of recordmcount. Reported-by: Ingo Molnar <mingo@elte.hu> Cc: John Reiser <jreiser@bitwagon.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'scripts/Makefile.build')
0 files changed, 0 insertions, 0 deletions

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