Re: [PATCH 1/4] kernel/trace: Introduce new APIs to process probe arguments
From: Song Chen
Date: Mon Nov 21 2022 - 21:05:54 EST
Hi,
在 2022/11/22 06:16, Masami Hiramatsu (Google) 写道:
On Wed, 16 Nov 2022 20:25:07 +0800
Song Chen <chensong_2000@xxxxxx> 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
Those APIs are going to merge similar implementations respectively
in kprobe/uprobe/eprobe.
Signed-off-by: Song Chen <chensong_2000@xxxxxx>
---
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);
Also, I would not like to see this "is_uprobe" check in the code. That is useless
when running this in the kernel. This is why I did this in trace_probe_tmpl.h as
an inlined function.
one of the intention is to merge process_fetch_insn*, that's why
is_uprobe is introduced here, otherwise, process_fetch_insn* doesn't
know which kind of probe it's dealing with.
So, sorting print_args function is OK for me, but the process_fetch_insn* should be
kept as inlined. Maybe some common code can be move to the trace_probe_tmpl.h as
inlined functions?
if i understand you correctly, you would like to remain
process_fetch_insn* as the way they are, no change.
Maybe i went too far, i will submit a new patchset to restore.
/Song
+ 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;
Ditto.
will do.
/Song
+ 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
Please do not add an internal header file only just for 1 file.
Will remove.
/Song
@@ -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
Ditto.
Thank you,
Ditto, thanks.
/Song
@@ -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
Thanks,