Skip to content

Commit

Permalink
kernel/trace: Provide default impelentations defined in trace_probe_t…
Browse files Browse the repository at this point in the history 
…mpl.h

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@189.cn>
  • Loading branch information
@intel-lab-lkp
Song Chen authored and intel-lab-lkp committed Nov 24, 2022
1 parent 9e8eb0e commit 596b7db
Show file tree
Hide file tree
Showing 4 changed files with 138 additions and 255 deletions.
144 changes: 0 additions & 144 deletions kernel/trace/trace_eprobe.c
View file
Expand Up @@ -320,64 +320,6 @@ 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;
Expand Down Expand Up @@ -420,92 +362,6 @@ 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)
Expand Down
7 changes: 4 additions & 3 deletions kernel/trace/trace_events_synth.c
View file
Expand Up @@ -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"
Expand Down Expand Up @@ -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 {
Expand Down Expand Up @@ -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;
}
Expand Down
102 changes: 0 additions & 102 deletions kernel/trace/trace_kprobe.c
View file
Expand Up @@ -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
Expand Down

0 comments on commit 596b7db

Please sign in to comment.