aca9120977
Tony Jones reported that the ftrace self tests on s390 do not work: <6>Testing dynamic ftrace ops #1: (0 0 0 0 0) FAILED! <6>Testing tracer irqsoff: <3>failed to start irqsoff tracer <4>.. no entries found ..FAILED! <6>Testing tracer wakeup: <3>failed to start wakeup tracer <4>.. no entries found ..FAILED! <6>Testing tracer function_graph: <4>Failed to init function_graph tracer, init returned -19 <4>FAILED! This happens because we forgot to adjust the instruction pointer that gets passed to the ftrace trace function by MCOUNT_INSN_SIZE. In addition change MCOUNT_INSN_SIZE to the correct value on 31 bit. It only worked so far because the to be patched instruction was identical. Reported-by: Tony Jones <tonyj@suse.com> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
66 lines
1.2 KiB
ArmAsm
66 lines
1.2 KiB
ArmAsm
/*
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* Copyright IBM Corp. 2008, 2009
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*
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* Author(s): Heiko Carstens <heiko.carstens@de.ibm.com>,
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*
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*/
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#include <linux/linkage.h>
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#include <asm/asm-offsets.h>
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#include <asm/ftrace.h>
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.section .kprobes.text, "ax"
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ENTRY(ftrace_stub)
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br %r14
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ENTRY(_mcount)
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#ifdef CONFIG_DYNAMIC_FTRACE
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br %r14
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ENTRY(ftrace_caller)
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#endif
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larl %r1,function_trace_stop
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icm %r1,0xf,0(%r1)
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bnzr %r14
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stmg %r2,%r5,32(%r15)
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stg %r14,112(%r15)
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lgr %r1,%r15
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aghi %r15,-160
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stg %r1,__SF_BACKCHAIN(%r15)
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lgr %r2,%r14
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lg %r3,168(%r15)
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aghi %r2,-MCOUNT_INSN_SIZE
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larl %r14,ftrace_trace_function
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lg %r14,0(%r14)
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basr %r14,%r14
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#ifdef CONFIG_FUNCTION_GRAPH_TRACER
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lg %r2,168(%r15)
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lg %r3,272(%r15)
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ENTRY(ftrace_graph_caller)
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# The bras instruction gets runtime patched to call prepare_ftrace_return.
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# See ftrace_enable_ftrace_graph_caller. The patched instruction is:
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# bras %r14,prepare_ftrace_return
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bras %r14,0f
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0: stg %r2,168(%r15)
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#endif
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aghi %r15,160
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lmg %r2,%r5,32(%r15)
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lg %r14,112(%r15)
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br %r14
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#ifdef CONFIG_FUNCTION_GRAPH_TRACER
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ENTRY(return_to_handler)
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stmg %r2,%r5,32(%r15)
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lgr %r1,%r15
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aghi %r15,-160
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stg %r1,__SF_BACKCHAIN(%r15)
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brasl %r14,ftrace_return_to_handler
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aghi %r15,160
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lgr %r14,%r2
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lmg %r2,%r5,32(%r15)
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br %r14
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#endif
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