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| author |   Ilya Leoshkevich <iii@linux.ibm.com> | 2021-07-28 23:25:45 +0200 |
|---|---|---|
| committer |   Heiko Carstens <hca@linux.ibm.com> | 2021-08-03 14:31:40 +0200 |
| commit | 67ccddf86621b18dbffe56f11a106774ee8f44bd (patch) | |
| tree | cbc130b1c3c4da92e7c87b8cd5c70942e697ab60 /kernel/trace | |
| parent | s390: move the install rule to arch/s390/Makefile (diff) | |
| download | linux-dev-67ccddf86621b18dbffe56f11a106774ee8f44bd.tar.xz linux-dev-67ccddf86621b18dbffe56f11a106774ee8f44bd.zip | |
ftrace: Introduce ftrace_need_init_nop()
Implementing live patching on s390 requires each function's prologue to
contain a very special kind of nop, which gcc and clang don't generate.
However, the current code assumes that if CC_USING_NOP_MCOUNT is
defined, then whatever the compiler generates is good enough.
Move the CC_USING_NOP_MCOUNT check into the new ftrace_need_init_nop()
macro, that the architectures can override.
An alternative solution is to disable using -mnop-mcount in the
Makefile, however, this makes the build logic (even) more complicated
and forces the arch-specific code to deal with the useless __fentry__
symbol.
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Link: https://lore.kernel.org/r/20210728212546.128248-2-iii@linux.ibm.com
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Diffstat (limited to 'kernel/trace')
| -rw-r--r-- | kernel/trace/ftrace.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 7b180f61e6d3..7efbc8aaf7f6 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -3100,6 +3100,7 @@ ops_references_rec(struct ftrace_ops *ops, struct dyn_ftrace *rec) static int ftrace_update_code(struct module *mod, struct ftrace_page *new_pgs) { + bool init_nop = ftrace_need_init_nop(); struct ftrace_page *pg; struct dyn_ftrace *p; u64 start, stop; @@ -3138,8 +3139,7 @@ static int ftrace_update_code(struct module *mod, struct ftrace_page *new_pgs) * Do the initial record conversion from mcount jump * to the NOP instructions. */ - if (!__is_defined(CC_USING_NOP_MCOUNT) && - !ftrace_nop_initialize(mod, p)) + if (init_nop && !ftrace_nop_initialize(mod, p)) break; update_cnt++; |