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Subject[RFC PATCH 2/3] tracing: introduce {calc,parse}_probe_offset() for FETCH_MTD_{symbol,deref}
Preparation to simplify the review of the next patch.

Add 2 "dummy" helpers used by FETCH_MTD_{symbol,deref} parse/fetch
code: calc_probe_offset(offset) which currently simply returns its
arg, and parse_probe_offset(name, offset) which calls kstrtol().

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
---
kernel/trace/trace_probe.c | 27 +++++++++++++++++++++------
1 files changed, 21 insertions(+), 6 deletions(-)

diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index dcf7780..723e6e9 100644
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -263,12 +263,14 @@ static struct symbol_cache *alloc_symbol_cache(const char *sym, long offset)
return sc;
}

+static long calc_probe_offset(unsigned long offset);
+
#define DEFINE_FETCH_symbol(type) \
static __kprobes void FETCH_FUNC_NAME(symbol, type)(struct pt_regs *regs,\
void *data, void *dest) \
{ \
struct symbol_cache *sc = data; \
- long off = sc->offset; \
+ long off = calc_probe_offset(sc->offset); \
if (sc->addr) \
fetch_memory_##type(regs, (void *)sc->addr + off, dest);\
else \
@@ -292,7 +294,7 @@ static __kprobes void FETCH_FUNC_NAME(deref, type)(struct pt_regs *regs,\
unsigned long addr; \
call_fetch(&dprm->orig, regs, &addr); \
if (addr) { \
- addr += dprm->offset; \
+ addr += calc_probe_offset(dprm->offset); \
fetch_memory_##type(regs, (void *)addr, dest); \
} else \
*(type *)dest = 0; \
@@ -487,6 +489,8 @@ static fetch_func_t get_fetch_size_function(const struct fetch_type *type,
return NULL;
}

+static int parse_probe_offset(const char *name, unsigned long *offset);
+
/* Split symbol and offset. */
int traceprobe_split_symbol_offset(char *symbol, unsigned long *offset)
{
@@ -495,8 +499,7 @@ int traceprobe_split_symbol_offset(char *symbol, unsigned long *offset)

tmp = strchr(symbol, '+');
if (tmp) {
- /* skip sign because kstrtoul doesn't accept '+' */
- ret = kstrtoul(tmp + 1, 0, offset);
+ ret = parse_probe_offset(tmp, offset);
if (ret)
return ret;

@@ -588,6 +591,19 @@ static int pseudo_reg_query_offset(const char *name)
return -EINVAL;
}

+static long calc_probe_offset(unsigned long offset)
+{
+ return offset;
+}
+
+static int parse_probe_offset(const char *name, unsigned long *offset)
+{
+ if (name[0] == '+') /* kstrtol() rejects '+' */
+ name++;
+
+ return kstrtol(name, 0, offset);
+}
+
/* Recursive argument parser */
static int parse_probe_arg(char *arg, const struct fetch_type *t,
struct fetch_param *f, bool is_return, bool is_kprobe)
@@ -641,14 +657,13 @@ static int parse_probe_arg(char *arg, const struct fetch_type *t,
break;

case '+': /* deref memory */
- arg++; /* Skip '+', because kstrtol() rejects it. */
case '-':
tmp = strchr(arg, '(');
if (!tmp)
break;

*tmp = '\0';
- ret = kstrtol(arg, 0, &offset);
+ ret = parse_probe_offset(arg, &offset);

if (ret)
break;
--
1.5.5.1



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