[PATCH v4 2/2] kernel/trace: Provide default impelentations defined in trace_probe_tmpl.h

From: Song Chen
Date: Wed Dec 28 2022 - 02:01:42 EST

There are 7 function definitions in trace_probe_tmpl.h, they are:

1, process_fetch_insn
2, fetch_store_strlen
3, fetch_store_string
4, fetch_store_strlen_user
5, fetch_store_string_user
6, probe_mem_read
7, probe_mem_read_user

Every C file which includes trace_probe_tmpl.h has to implement them,
otherwise it gets warnings and errors. However, some of them are identical,
like kprobe and eprobe, as a result, there is a lot redundant code in those
2 files.

This patch would like to provide default behaviors for those functions
which kprobe and eprobe can share by just including trace_probe_kernel.h
with trace_probe_tmpl.h together.

It removes redundant code, increases readability, and more importantly,
makes it easier to introduce a new feature based on trace probe
(it's possible).

Signed-off-by: Song Chen <chensong_2000@xxxxxx>
Reported-by: kernel test robot <lkp@xxxxxxxxx>

---
v2:
1, reorganize patchset

v3:
1, mark nokprobe_inline for get_event_field
2, remove warnings reported from kernel test robot
3, fix errors reported from kernel test robot

v4:
1, reset changes in v3(2) and v3(3), they are not reasonable fix.
2, I intended to introduce a new header file to exclude
trace_events_synth.c out of the patch. However, after looking
further, i found the errors in [1] are introduced by this patch,
but the warning in [1] are not. The errors can be fixed by adding
"#ifdef CONFIG_HAVE_REGS_AND_STACK_ACCESS_API".

[1]:https://lore.kernel.org/lkml/202211301946.pkLE4PDp-lkp@xxxxxxxxx/
---
kernel/trace/trace_eprobe.c | 144 ------------------------------
kernel/trace/trace_events_synth.c | 7 +-
kernel/trace/trace_kprobe.c | 102 ---------------------
kernel/trace/trace_probe_kernel.h | 143 +++++++++++++++++++++++++++--
4 files changed, 141 insertions(+), 255 deletions(-)

diff --git a/kernel/trace/trace_eprobe.c b/kernel/trace/trace_eprobe.c
index bdb26eee7a0c..60ced4a7a25d 100644
--- a/kernel/trace/trace_eprobe.c
+++ b/kernel/trace/trace_eprobe.c
@@ -319,64 +319,6 @@ print_eprobe_event(struct trace_iterator *iter, int flags,
return trace_handle_return(s);
}

-static unsigned long get_event_field(struct fetch_insn *code, void *rec)
-{
- struct ftrace_event_field *field = code->data;
- unsigned long val;
- void *addr;
-
- addr = rec + field->offset;
-
- if (is_string_field(field)) {
- switch (field->filter_type) {
- case FILTER_DYN_STRING:
- val = (unsigned long)(rec + (*(unsigned int *)addr & 0xffff));
- break;
- case FILTER_RDYN_STRING:
- val = (unsigned long)(addr + (*(unsigned int *)addr & 0xffff));
- break;
- case FILTER_STATIC_STRING:
- val = (unsigned long)addr;
- break;
- case FILTER_PTR_STRING:
- val = (unsigned long)(*(char *)addr);
- break;
- default:
- WARN_ON_ONCE(1);
- return 0;
- }
- return val;
- }
-
- switch (field->size) {
- case 1:
- if (field->is_signed)
- val = *(char *)addr;
- else
- val = *(unsigned char *)addr;
- break;
- case 2:
- if (field->is_signed)
- val = *(short *)addr;
- else
- val = *(unsigned short *)addr;
- break;
- case 4:
- if (field->is_signed)
- val = *(int *)addr;
- else
- val = *(unsigned int *)addr;
- break;
- default:
- if (field->is_signed)
- val = *(long *)addr;
- else
- val = *(unsigned long *)addr;
- break;
- }
- return val;
-}
-
static int get_eprobe_size(struct trace_probe *tp, void *rec)
{
struct fetch_insn *code;
@@ -419,92 +361,6 @@ static int get_eprobe_size(struct trace_probe *tp, void *rec)
return ret;
}

-/* Kprobe specific fetch functions */
-
-/* Note that we don't verify it, since the code does not come from user space */
-static int
-process_fetch_insn(struct fetch_insn *code, void *rec, void *dest,
- void *base)
-{
- unsigned long val;
-
- retry:
- switch (code->op) {
- case FETCH_OP_TP_ARG:
- val = get_event_field(code, rec);
- break;
- case FETCH_OP_IMM:
- val = code->immediate;
- break;
- case FETCH_OP_COMM:
- val = (unsigned long)current->comm;
- break;
- case FETCH_OP_DATA:
- val = (unsigned long)code->data;
- break;
- case FETCH_NOP_SYMBOL: /* Ignore a place holder */
- code++;
- goto retry;
- default:
- return -EILSEQ;
- }
- code++;
- return process_fetch_insn_bottom(code, val, dest, base);
-}
-NOKPROBE_SYMBOL(process_fetch_insn)
-
-/* Return the length of string -- including null terminal byte */
-static nokprobe_inline int
-fetch_store_strlen_user(unsigned long addr)
-{
- return kern_fetch_store_strlen_user(addr);
-}
-
-/* Return the length of string -- including null terminal byte */
-static nokprobe_inline int
-fetch_store_strlen(unsigned long addr)
-{
- return kern_fetch_store_strlen(addr);
-}
-
-/*
- * Fetch a null-terminated string from user. Caller MUST set *(u32 *)buf
- * with max length and relative data location.
- */
-static nokprobe_inline int
-fetch_store_string_user(unsigned long addr, void *dest, void *base)
-{
- return kern_fetch_store_string_user(addr, dest, base);
-}
-
-/*
- * Fetch a null-terminated string. Caller MUST set *(u32 *)buf with max
- * length and relative data location.
- */
-static nokprobe_inline int
-fetch_store_string(unsigned long addr, void *dest, void *base)
-{
- return kern_fetch_store_string(addr, dest, base);
-}
-
-static nokprobe_inline int
-probe_mem_read_user(void *dest, void *src, size_t size)
-{
- const void __user *uaddr = (__force const void __user *)src;
-
- return copy_from_user_nofault(dest, uaddr, size);
-}
-
-static nokprobe_inline int
-probe_mem_read(void *dest, void *src, size_t size)
-{
-#ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
- if ((unsigned long)src < TASK_SIZE)
- return probe_mem_read_user(dest, src, size);
-#endif
- return copy_from_kernel_nofault(dest, src, size);
-}
-
/* eprobe handler */
static inline void
__eprobe_trace_func(struct eprobe_data *edata, void *rec)
diff --git a/kernel/trace/trace_events_synth.c b/kernel/trace/trace_events_synth.c
index e310052dc83c..7460f18ba973 100644
--- a/kernel/trace/trace_events_synth.c
+++ b/kernel/trace/trace_events_synth.c
@@ -18,6 +18,7 @@
#include <linux/trace_events.h>
#include <trace/events/mmflags.h>
#include "trace_probe.h"
+#include "trace_probe_tmpl.h"
#include "trace_probe_kernel.h"

#include "trace_synth.h"
@@ -420,12 +421,12 @@ static unsigned int trace_string(struct synth_trace_event *entry,
data_offset += event->n_u64 * sizeof(u64);
data_offset += data_size;

- len = kern_fetch_store_strlen((unsigned long)str_val);
+ len = fetch_store_strlen((unsigned long)str_val);

data_offset |= len << 16;
*(u32 *)&entry->fields[*n_u64] = data_offset;

- ret = kern_fetch_store_string((unsigned long)str_val, &entry->fields[*n_u64], entry);
+ ret = fetch_store_string((unsigned long)str_val, &entry->fields[*n_u64], entry);

(*n_u64)++;
} else {
@@ -473,7 +474,7 @@ static notrace void trace_event_raw_event_synth(void *__data,
val_idx = var_ref_idx[field_pos];
str_val = (char *)(long)var_ref_vals[val_idx];

- len = kern_fetch_store_strlen((unsigned long)str_val);
+ len = fetch_store_strlen((unsigned long)str_val);

fields_size += len;
}
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index a4ffa864dbb7..c2e0b741ae82 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -1218,108 +1218,6 @@ static const struct file_operations kprobe_profile_ops = {
.release = seq_release,
};

-/* Kprobe specific fetch functions */
-
-/* Return the length of string -- including null terminal byte */
-static nokprobe_inline int
-fetch_store_strlen_user(unsigned long addr)
-{
- return kern_fetch_store_strlen_user(addr);
-}
-
-/* Return the length of string -- including null terminal byte */
-static nokprobe_inline int
-fetch_store_strlen(unsigned long addr)
-{
- return kern_fetch_store_strlen(addr);
-}
-
-/*
- * Fetch a null-terminated string from user. Caller MUST set *(u32 *)buf
- * with max length and relative data location.
- */
-static nokprobe_inline int
-fetch_store_string_user(unsigned long addr, void *dest, void *base)
-{
- return kern_fetch_store_string_user(addr, dest, base);
-}
-
-/*
- * Fetch a null-terminated string. Caller MUST set *(u32 *)buf with max
- * length and relative data location.
- */
-static nokprobe_inline int
-fetch_store_string(unsigned long addr, void *dest, void *base)
-{
- return kern_fetch_store_string(addr, dest, base);
-}
-
-static nokprobe_inline int
-probe_mem_read_user(void *dest, void *src, size_t size)
-{
- const void __user *uaddr = (__force const void __user *)src;
-
- return copy_from_user_nofault(dest, uaddr, size);
-}
-
-static nokprobe_inline int
-probe_mem_read(void *dest, void *src, size_t size)
-{
-#ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
- if ((unsigned long)src < TASK_SIZE)
- return probe_mem_read_user(dest, src, size);
-#endif
- return copy_from_kernel_nofault(dest, src, size);
-}
-
-/* Note that we don't verify it, since the code does not come from user space */
-static int
-process_fetch_insn(struct fetch_insn *code, void *rec, void *dest,
- void *base)
-{
- struct pt_regs *regs = rec;
- unsigned long val;
-
-retry:
- /* 1st stage: get value from context */
- switch (code->op) {
- case FETCH_OP_REG:
- val = regs_get_register(regs, code->param);
- break;
- case FETCH_OP_STACK:
- val = regs_get_kernel_stack_nth(regs, code->param);
- break;
- case FETCH_OP_STACKP:
- val = kernel_stack_pointer(regs);
- break;
- case FETCH_OP_RETVAL:
- val = regs_return_value(regs);
- break;
- case FETCH_OP_IMM:
- val = code->immediate;
- break;
- case FETCH_OP_COMM:
- val = (unsigned long)current->comm;
- break;
- case FETCH_OP_DATA:
- val = (unsigned long)code->data;
- break;
-#ifdef CONFIG_HAVE_FUNCTION_ARG_ACCESS_API
- case FETCH_OP_ARG:
- val = regs_get_kernel_argument(regs, code->param);
- break;
-#endif
- case FETCH_NOP_SYMBOL: /* Ignore a place holder */
- code++;
- goto retry;
- default:
- return -EILSEQ;
- }
- code++;
-
- return process_fetch_insn_bottom(code, val, dest, base);
-}
-NOKPROBE_SYMBOL(process_fetch_insn)

/* Kprobe handler */
static nokprobe_inline void
diff --git a/kernel/trace/trace_probe_kernel.h b/kernel/trace/trace_probe_kernel.h
index 77dbd9ff9782..39f44513ec4e 100644
--- a/kernel/trace/trace_probe_kernel.h
+++ b/kernel/trace/trace_probe_kernel.h
@@ -12,7 +12,7 @@
*/
/* Return the length of string -- including null terminal byte */
static nokprobe_inline int
-kern_fetch_store_strlen_user(unsigned long addr)
+fetch_store_strlen_user(unsigned long addr)
{
const void __user *uaddr = (__force const void __user *)addr;
int ret;
@@ -29,14 +29,14 @@ kern_fetch_store_strlen_user(unsigned long addr)

/* Return the length of string -- including null terminal byte */
static nokprobe_inline int
-kern_fetch_store_strlen(unsigned long addr)
+fetch_store_strlen(unsigned long addr)
{
int ret, len = 0;
u8 c;

#ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
if (addr < TASK_SIZE)
- return kern_fetch_store_strlen_user(addr);
+ return fetch_store_strlen_user(addr);
#endif

do {
@@ -63,7 +63,7 @@ static nokprobe_inline void set_data_loc(int ret, void *dest, void *__dest, void
* with max length and relative data location.
*/
static nokprobe_inline int
-kern_fetch_store_string_user(unsigned long addr, void *dest, void *base)
+fetch_store_string_user(unsigned long addr, void *dest, void *base)
{
const void __user *uaddr = (__force const void __user *)addr;
int maxlen = get_loc_len(*(u32 *)dest);
@@ -86,7 +86,7 @@ kern_fetch_store_string_user(unsigned long addr, void *dest, void *base)
* length and relative data location.
*/
static nokprobe_inline int
-kern_fetch_store_string(unsigned long addr, void *dest, void *base)
+fetch_store_string(unsigned long addr, void *dest, void *base)
{
int maxlen = get_loc_len(*(u32 *)dest);
void *__dest;
@@ -94,7 +94,7 @@ kern_fetch_store_string(unsigned long addr, void *dest, void *base)

#ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
if ((unsigned long)addr < TASK_SIZE)
- return kern_fetch_store_string_user(addr, dest, base);
+ return fetch_store_string_user(addr, dest, base);
#endif

if (unlikely(!maxlen))
@@ -112,4 +112,135 @@ kern_fetch_store_string(unsigned long addr, void *dest, void *base)
return ret;
}

+static nokprobe_inline int
+probe_mem_read_user(void *dest, void *src, size_t size)
+{
+ const void __user *uaddr = (__force const void __user *)src;
+
+ return copy_from_user_nofault(dest, uaddr, size);
+}
+
+static nokprobe_inline int
+probe_mem_read(void *dest, void *src, size_t size)
+{
+#ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
+ if ((unsigned long)src < TASK_SIZE)
+ return probe_mem_read_user(dest, src, size);
+#endif
+ return copy_from_kernel_nofault(dest, src, size);
+}
+
+static nokprobe_inline unsigned long
+get_event_field(struct fetch_insn *code, void *rec)
+{
+ struct ftrace_event_field *field = code->data;
+ unsigned long val;
+ void *addr;
+
+ addr = rec + field->offset;
+
+ if (is_string_field(field)) {
+ switch (field->filter_type) {
+ case FILTER_DYN_STRING:
+ val = (unsigned long)(rec + (*(unsigned int *)addr & 0xffff));
+ break;
+ case FILTER_RDYN_STRING:
+ val = (unsigned long)(addr + (*(unsigned int *)addr & 0xffff));
+ break;
+ case FILTER_STATIC_STRING:
+ val = (unsigned long)addr;
+ break;
+ case FILTER_PTR_STRING:
+ val = (unsigned long)(*(char *)addr);
+ break;
+ default:
+ WARN_ON_ONCE(1);
+ return 0;
+ }
+ return val;
+ }
+
+ switch (field->size) {
+ case 1:
+ if (field->is_signed)
+ val = *(char *)addr;
+ else
+ val = *(unsigned char *)addr;
+ break;
+ case 2:
+ if (field->is_signed)
+ val = *(short *)addr;
+ else
+ val = *(unsigned short *)addr;
+ break;
+ case 4:
+ if (field->is_signed)
+ val = *(int *)addr;
+ else
+ val = *(unsigned int *)addr;
+ break;
+ default:
+ if (field->is_signed)
+ val = *(long *)addr;
+ else
+ val = *(unsigned long *)addr;
+ break;
+ }
+ return val;
+}
+
+/* Note that we don't verify it, since the code does not come from user space */
+static int
+process_fetch_insn(struct fetch_insn *code, void *rec, void *dest,
+ void *base)
+{
+ struct pt_regs *regs = rec;
+ unsigned long val;
+
+retry:
+ /* 1st stage: get value from context */
+ switch (code->op) {
+#ifdef CONFIG_HAVE_REGS_AND_STACK_ACCESS_API
+ case FETCH_OP_REG:
+ val = regs_get_register(regs, code->param);
+ break;
+ case FETCH_OP_STACK:
+ val = regs_get_kernel_stack_nth(regs, code->param);
+ break;
+ case FETCH_OP_STACKP:
+ val = kernel_stack_pointer(regs);
+ break;
+ case FETCH_OP_RETVAL:
+ val = regs_return_value(regs);
+ break;
+#endif
+ case FETCH_OP_IMM:
+ val = code->immediate;
+ break;
+ case FETCH_OP_COMM:
+ val = (unsigned long)current->comm;
+ break;
+ case FETCH_OP_DATA:
+ val = (unsigned long)code->data;
+ break;
+#ifdef CONFIG_HAVE_FUNCTION_ARG_ACCESS_API
+ case FETCH_OP_ARG:
+ val = regs_get_kernel_argument(regs, code->param);
+ break;
+#endif
+ case FETCH_NOP_SYMBOL: /* Ignore a place holder */
+ code++;
+ goto retry;
+ case FETCH_OP_TP_ARG:
+ val = get_event_field(code, rec);
+ break;
+ default:
+ return -EILSEQ;
+ }
+ code++;
+
+ return process_fetch_insn_bottom(code, val, dest, base);
+}
+NOKPROBE_SYMBOL(process_fetch_insn)
+
#endif /* __TRACE_PROBE_KERNEL_H_ */
--
2.25.1