lkml.org 
[lkml]   [2022]   [Nov]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 1/4] kernel/trace: Introduce new APIs to process probe arguments
Hi Song,

On Wed, 16 Nov 2022 20:25:07 +0800
Song Chen <chensong_2000@189.cn> wrote:

> Introduce 3 new APIs:
> 1. trace_probe_get_data_size: get arguments' data size
> 2. trace_probe_store_args: store aruguments into ring buffer
> 3. trace_probe_print_args: print arguments into trace file

Ah, I meant that split the patches into

Introduce trace_probe_get_data_size() and use it in *probes
Introduce trace_probe_store_args() and use it in *probes
Introduce trace_probe_print_args and use it in *probes

Then we can easily understand by its meaning.

Can you reform this series again?

Thank you,

>
> Those APIs are going to merge similar implementations respectively
> in kprobe/uprobe/eprobe.
>
> Signed-off-by: Song Chen <chensong_2000@189.cn>
> ---
> kernel/trace/trace_probe.c | 305 ++++++++++++++++++++++++++++++
> kernel/trace/trace_probe.h | 5 +
> kernel/trace/trace_probe_common.h | 69 +++++++
> kernel/trace/trace_probe_user.h | 95 ++++++++++
> 4 files changed, 474 insertions(+)
> create mode 100644 kernel/trace/trace_probe_common.h
> create mode 100644 kernel/trace/trace_probe_user.h
>
> diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
> index 36dff277de46..303f057bd2f7 100644
> --- a/kernel/trace/trace_probe.c
> +++ b/kernel/trace/trace_probe.c
> @@ -12,6 +12,9 @@
> #define pr_fmt(fmt) "trace_probe: " fmt
>
> #include "trace_probe.h"
> +#include "trace_probe_kernel.h"
> +#include "trace_probe_user.h"
> +#include "trace_probe_common.h"
>
> #undef C
> #define C(a, b) b
> @@ -1218,3 +1221,305 @@ int trace_probe_create(const char *raw_command, int (*createfn)(int, const char
>
> return ret;
> }
> +
> +/* From the 2nd stage, routine is same */
> +static nokprobe_inline int
> +process_fetch_insn_bottom(struct fetch_insn *code, unsigned long val,
> + void *dest, void *base, int flags)
> +{
> + struct fetch_insn *s3 = NULL;
> + int total = 0, ret = 0, i = 0;
> + u32 loc = 0;
> + unsigned long lval = val;
> + int is_uprobe = flags & TRACE_EVENT_FL_UPROBE;
> +
> +stage2:
> + /* 2nd stage: dereference memory if needed */
> + do {
> + if (code->op == FETCH_OP_DEREF) {
> + lval = val;
> + ret = probe_mem_read(&val, (void *)val + code->offset,
> + sizeof(val));
> + } else if (code->op == FETCH_OP_UDEREF) {
> + lval = val;
> + ret = probe_mem_read_user(&val,
> + (void *)val + code->offset, sizeof(val));
> + } else
> + break;
> + if (ret)
> + return ret;
> + code++;
> + } while (1);
> +
> + s3 = code;
> +stage3:
> + /* 3rd stage: store value to buffer */
> + if (unlikely(!dest)) {
> + if (code->op == FETCH_OP_ST_STRING) {
> + if (is_uprobe)
> + ret = user_fetch_store_strlen(val + code->offset);
> + else
> + ret = kern_fetch_store_strlen(val + code->offset);
> + code++;
> + goto array;
> + } else if (code->op == FETCH_OP_ST_USTRING) {
> + if (is_uprobe)
> + ret += user_fetch_store_strlen_user(val + code->offset);
> + else
> + ret += kern_fetch_store_strlen_user(val + code->offset);
> + code++;
> + goto array;
> + } else
> + return -EILSEQ;
> + }
> +
> + switch (code->op) {
> + case FETCH_OP_ST_RAW:
> + fetch_store_raw(val, code, dest);
> + break;
> + case FETCH_OP_ST_MEM:
> + probe_mem_read(dest, (void *)val + code->offset, code->size);
> + break;
> + case FETCH_OP_ST_UMEM:
> + probe_mem_read_user(dest, (void *)val + code->offset, code->size);
> + break;
> + case FETCH_OP_ST_STRING:
> + loc = *(u32 *)dest;
> + if (is_uprobe)
> + ret = user_fetch_store_string(val + code->offset, dest, base);
> + else
> + ret = kern_fetch_store_string(val + code->offset, dest, base);
> + break;
> + case FETCH_OP_ST_USTRING:
> + loc = *(u32 *)dest;
> + if (is_uprobe)
> + ret = user_fetch_store_string_user(val + code->offset, dest, base);
> + else
> + ret = kern_fetch_store_string_user(val + code->offset, dest, base);
> + break;
> + default:
> + return -EILSEQ;
> + }
> + code++;
> +
> + /* 4th stage: modify stored value if needed */
> + if (code->op == FETCH_OP_MOD_BF) {
> + fetch_apply_bitfield(code, dest);
> + code++;
> + }
> +
> +array:
> + /* the last stage: Loop on array */
> + if (code->op == FETCH_OP_LP_ARRAY) {
> + total += ret;
> + if (++i < code->param) {
> + code = s3;
> + if (s3->op != FETCH_OP_ST_STRING &&
> + s3->op != FETCH_OP_ST_USTRING) {
> + dest += s3->size;
> + val += s3->size;
> + goto stage3;
> + }
> + code--;
> + val = lval + sizeof(char *);
> + if (dest) {
> + dest += sizeof(u32);
> + *(u32 *)dest = update_data_loc(loc, ret);
> + }
> + goto stage2;
> + }
> + code++;
> + ret = total;
> + }
> +
> + return code->op == FETCH_OP_END ? ret : -EILSEQ;
> +}
> +
> +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;
> +}
> +
> +/* 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, int flags)
> +{
> + struct pt_regs *regs = rec;
> + unsigned long val;
> + int is_uprobe = flags & TRACE_EVENT_FL_UPROBE;
> +
> +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:
> + if (is_uprobe)
> + val = get_user_stack_nth(regs, code->param);
> + else
> + val = regs_get_kernel_stack_nth(regs, code->param);
> + break;
> + case FETCH_OP_STACKP:
> + if (is_uprobe)
> + val = user_stack_pointer(regs);
> + else
> + 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;
> + 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, flags);
> +}
> +NOKPROBE_SYMBOL(process_fetch_insn)
> +
> +/* Sum up total data length for dynamic arrays (strings) */
> +int trace_probe_get_data_size(struct trace_probe *tp, struct pt_regs *regs)
> +{
> + struct probe_arg *arg;
> + int i, len, ret = 0;
> + struct trace_event_call *call = trace_probe_event_call(tp);
> +
> + for (i = 0; i < tp->nr_args; i++) {
> + arg = tp->args + i;
> + if (unlikely(arg->dynamic)) {
> + len = process_fetch_insn(arg->code, regs, NULL, NULL, call->flags);
> + if (len > 0)
> + ret += len;
> + }
> + }
> +
> + return ret;
> +}
> +
> +void trace_probe_store_args(void *data, struct trace_probe *tp, void *rec,
> + int header_size, int maxlen)
> +{
> + struct probe_arg *arg;
> + void *base = data - header_size;
> + void *dyndata = data + tp->size;
> + u32 *dl; /* Data location */
> + int ret, i;
> + struct trace_event_call *call = trace_probe_event_call(tp);
> +
> + for (i = 0; i < tp->nr_args; i++) {
> + arg = tp->args + i;
> + dl = data + arg->offset;
> + /* Point the dynamic data area if needed */
> + if (unlikely(arg->dynamic))
> + *dl = make_data_loc(maxlen, dyndata - base);
> + ret = process_fetch_insn(arg->code, rec, dl, base, call->flags);
> + if (unlikely(ret < 0 && arg->dynamic)) {
> + *dl = make_data_loc(0, dyndata - base);
> + } else {
> + dyndata += ret;
> + maxlen -= ret;
> + }
> + }
> +}
> +
> +int trace_probe_print_args(struct trace_seq *s, struct probe_arg *args, int nr_args,
> + u8 *data, void *field)
> +{
> + void *p;
> + int i, j;
> +
> + for (i = 0; i < nr_args; i++) {
> + struct probe_arg *a = args + i;
> +
> + trace_seq_printf(s, " %s=", a->name);
> + if (likely(!a->count)) {
> + if (!a->type->print(s, data + a->offset, field))
> + return -ENOMEM;
> + continue;
> + }
> + trace_seq_putc(s, '{');
> + p = data + a->offset;
> + for (j = 0; j < a->count; j++) {
> + if (!a->type->print(s, p, field))
> + return -ENOMEM;
> + trace_seq_putc(s, j == a->count - 1 ? '}' : ',');
> + p += a->type->size;
> + }
> + }
> + return 0;
> +}
> diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
> index de38f1c03776..4f044047b748 100644
> --- a/kernel/trace/trace_probe.h
> +++ b/kernel/trace/trace_probe.h
> @@ -343,6 +343,11 @@ int trace_probe_compare_arg_type(struct trace_probe *a, struct trace_probe *b);
> bool trace_probe_match_command_args(struct trace_probe *tp,
> int argc, const char **argv);
> int trace_probe_create(const char *raw_command, int (*createfn)(int, const char **));
> +int trace_probe_get_data_size(struct trace_probe *tp, struct pt_regs *regs);
> +void trace_probe_store_args(void *data, struct trace_probe *tp, void *rec,
> + int header_size, int maxlen);
> +int trace_probe_print_args(struct trace_seq *s, struct probe_arg *args, int nr_args,
> + u8 *data, void *field);
>
> #define trace_probe_for_each_link(pos, tp) \
> list_for_each_entry(pos, &(tp)->event->files, list)
> diff --git a/kernel/trace/trace_probe_common.h b/kernel/trace/trace_probe_common.h
> new file mode 100644
> index 000000000000..b8d77447fe0c
> --- /dev/null
> +++ b/kernel/trace/trace_probe_common.h
> @@ -0,0 +1,69 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef __TRACE_PROBE_COMMON_H_
> +#define __TRACE_PROBE_COMMON_H_
> +
> +#define FAULT_STRING "(fault)"
> +
> +static nokprobe_inline void
> +fetch_store_raw(unsigned long val, struct fetch_insn *code, void *buf)
> +{
> + switch (code->size) {
> + case 1:
> + *(u8 *)buf = (u8)val;
> + break;
> + case 2:
> + *(u16 *)buf = (u16)val;
> + break;
> + case 4:
> + *(u32 *)buf = (u32)val;
> + break;
> + case 8:
> + //TBD: 32bit signed
> + *(u64 *)buf = (u64)val;
> + break;
> + default:
> + *(unsigned long *)buf = val;
> + }
> +}
> +
> +static nokprobe_inline void
> +fetch_apply_bitfield(struct fetch_insn *code, void *buf)
> +{
> + switch (code->basesize) {
> + case 1:
> + *(u8 *)buf <<= code->lshift;
> + *(u8 *)buf >>= code->rshift;
> + break;
> + case 2:
> + *(u16 *)buf <<= code->lshift;
> + *(u16 *)buf >>= code->rshift;
> + break;
> + case 4:
> + *(u32 *)buf <<= code->lshift;
> + *(u32 *)buf >>= code->rshift;
> + break;
> + case 8:
> + *(u64 *)buf <<= code->lshift;
> + *(u64 *)buf >>= code->rshift;
> + break;
> + }
> +}
> +
> +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);
> +}
> +#endif /* __TRACE_PROBE_COMMON_H_ */
> diff --git a/kernel/trace/trace_probe_user.h b/kernel/trace/trace_probe_user.h
> new file mode 100644
> index 000000000000..2104ccb44d56
> --- /dev/null
> +++ b/kernel/trace/trace_probe_user.h
> @@ -0,0 +1,95 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef __TRACE_PROBE_USER_H_
> +#define __TRACE_PROBE_USER_H_
> +
> +#define FAULT_STRING "(fault)"
> +
> +/*
> + * Fetch a null-terminated string. Caller MUST set *(u32 *)dest with max
> + * length and relative data location.
> + */
> +static nokprobe_inline int
> +user_fetch_store_string(unsigned long addr, void *dest, void *base)
> +{
> + long ret;
> + u32 loc = *(u32 *)dest;
> + int maxlen = get_loc_len(loc);
> + u8 *dst = get_loc_data(dest, base);
> + void __user *src = (void __force __user *) addr;
> +
> + if (unlikely(!maxlen))
> + return -ENOMEM;
> +
> + if (addr == FETCH_TOKEN_COMM)
> + ret = strlcpy(dst, current->comm, maxlen);
> + else
> + ret = strncpy_from_user(dst, src, maxlen);
> + if (ret >= 0) {
> + if (ret == maxlen)
> + dst[ret - 1] = '\0';
> + else
> + /*
> + * Include the terminating null byte. In this case it
> + * was copied by strncpy_from_user but not accounted
> + * for in ret.
> + */
> + ret++;
> + *(u32 *)dest = make_data_loc(ret, (void *)dst - base);
> + }
> +
> + return ret;
> +}
> +
> +static nokprobe_inline int
> +user_fetch_store_string_user(unsigned long addr, void *dest, void *base)
> +{
> + return user_fetch_store_string(addr, dest, base);
> +}
> +
> +/* Return the length of string -- including null terminal byte */
> +static nokprobe_inline int
> +user_fetch_store_strlen(unsigned long addr)
> +{
> + int len;
> + void __user *vaddr = (void __force __user *) addr;
> +
> + if (addr == FETCH_TOKEN_COMM)
> + len = strlen(current->comm) + 1;
> + else
> + len = strnlen_user(vaddr, MAX_STRING_SIZE);
> +
> + return (len > MAX_STRING_SIZE) ? 0 : len;
> +}
> +
> +static nokprobe_inline int
> +user_fetch_store_strlen_user(unsigned long addr)
> +{
> + return user_fetch_store_strlen(addr);
> +}
> +
> +#ifdef CONFIG_STACK_GROWSUP
> +static unsigned long adjust_stack_addr(unsigned long addr, unsigned int n)
> +{
> + return addr - (n * sizeof(long));
> +}
> +#else
> +static unsigned long adjust_stack_addr(unsigned long addr, unsigned int n)
> +{
> + return addr + (n * sizeof(long));
> +}
> +#endif
> +
> +static unsigned long get_user_stack_nth(struct pt_regs *regs, unsigned int n)
> +{
> + unsigned long ret;
> + unsigned long addr = user_stack_pointer(regs);
> +
> + addr = adjust_stack_addr(addr, n);
> +
> + if (copy_from_user(&ret, (void __force __user *) addr, sizeof(ret)))
> + return 0;
> +
> + return ret;
> +}
> +
> +#endif /* __TRACE_PROBE_USER_H_ */
> --
> 2.25.1
>


--
Masami Hiramatsu (Google) <mhiramat@kernel.org>

\
 
 \ /
  Last update: 2022-11-21 23:02    [W:1.947 / U:0.340 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site