[PATCH 5/7] powerpc/ftrace: Update ftrace_location() for powerpc -mprofile-kernel
From: Naveen N. Rao <hidden>
Date: 2019-06-18 14:50:17
Also in:
lkml
Subsystem:
function hooks (ftrace), linux for powerpc (32-bit and 64-bit), the rest, tracing · Maintainers:
Steven Rostedt, Masami Hiramatsu, Madhavan Srinivasan, Linus Torvalds
Now that we are patching the preceding 'mflr r0' instruction with -mprofile-kernel, we need to update ftrace_location[_range]() to recognise that as being part of ftrace. To do this, we make a small change to ftrace_location_range() and convert ftrace_cmp_recs() into a weak function. We implement a custom version of ftrace_cmp_recs() which looks at the instruction preceding the branch to _mcount() and marks that instruction as belonging to ftrace if it is a 'nop' or 'mflr r0'. Signed-off-by: Naveen N. Rao <redacted> --- arch/powerpc/kernel/trace/ftrace.c | 31 ++++++++++++++++++++++++++++++ include/linux/ftrace.h | 1 + kernel/trace/ftrace.c | 4 ++-- 3 files changed, 34 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/kernel/trace/ftrace.c b/arch/powerpc/kernel/trace/ftrace.c
index 5e2b29808af1..b84046e43207 100644
--- a/arch/powerpc/kernel/trace/ftrace.c
+++ b/arch/powerpc/kernel/trace/ftrace.c@@ -951,6 +951,37 @@ void arch_ftrace_update_code(int command) } #ifdef CONFIG_MPROFILE_KERNEL +/* + * We need to check if the previous instruction is a 'nop' or 'mflr r0'. + * If so, we will patch those subsequently and that instruction must be + * considered as part of ftrace. + */ +int ftrace_cmp_recs(const void *a, const void *b) +{ + const struct dyn_ftrace *key = a; + const struct dyn_ftrace *rec = b; + unsigned int op; + + if (key->flags < rec->ip - MCOUNT_INSN_SIZE) + return -1; + if (key->ip >= rec->ip + MCOUNT_INSN_SIZE) + return 1; + + if (key->flags > rec->ip) + return 0; + + /* check the previous instruction */ + if (probe_kernel_read(&op, (void *)rec->ip - MCOUNT_INSN_SIZE, + sizeof(op))) + /* assume we own it */ + return 0; + + if (op != PPC_INST_NOP && op != PPC_INST_MFLR) + return -1; + + return 0; +} + /* Returns 1 if we patched in the mflr */ static int __ftrace_make_call_prep(struct dyn_ftrace *rec) {
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index fa653a561da5..9941987bf510 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h@@ -435,6 +435,7 @@ struct dyn_ftrace *ftrace_rec_iter_record(struct ftrace_rec_iter *iter); int ftrace_update_record(struct dyn_ftrace *rec, int enable); int ftrace_test_record(struct dyn_ftrace *rec, int enable); void ftrace_run_stop_machine(int command); +int ftrace_cmp_recs(const void *a, const void *b); unsigned long ftrace_location(unsigned long ip); unsigned long ftrace_location_range(unsigned long start, unsigned long end); unsigned long ftrace_get_addr_new(struct dyn_ftrace *rec);
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 21d8e201ee80..b5c61db0b452 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c@@ -1517,7 +1517,7 @@ ftrace_ops_test(struct ftrace_ops *ops, unsigned long ip, void *regs) } -static int ftrace_cmp_recs(const void *a, const void *b) +int __weak ftrace_cmp_recs(const void *a, const void *b) { const struct dyn_ftrace *key = a; const struct dyn_ftrace *rec = b;
@@ -1551,7 +1551,7 @@ unsigned long ftrace_location_range(unsigned long start, unsigned long end) key.flags = end; /* overload flags, as it is unsigned long */ for (pg = ftrace_pages_start; pg; pg = pg->next) { - if (end < pg->records[0].ip || + if (end <= pg->records[0].ip || start >= (pg->records[pg->index - 1].ip + MCOUNT_INSN_SIZE)) continue; rec = bsearch(&key, pg->records, pg->index,
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2.22.0