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libbpf: Refactor parse_usdt_arg() to re-use code
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The parse_usdt_arg() function is defined differently for each
architecture but the last part of the function is repeated
verbatim for each architecture.

Refactor parse_usdt_arg() to fill the arg_sz and then do the repeated
post-processing in parse_usdt_spec().

Signed-off-by: Puranjay Mohan <puranjay12@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20230307120440.25941-2-puranjay12@gmail.com
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Puranjay Mohan authored and Andrii Nakryiko committed Mar 7, 2023
1 parent 3ecde21 commit 98e678e
Showing 1 changed file with 42 additions and 82 deletions.
124 changes: 42 additions & 82 deletions tools/lib/bpf/usdt.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1141,12 +1141,13 @@ static int parse_usdt_note(Elf *elf, const char *path, GElf_Nhdr *nhdr,
return 0;
}

static int parse_usdt_arg(const char *arg_str, int arg_num, struct usdt_arg_spec *arg);
static int parse_usdt_arg(const char *arg_str, int arg_num, struct usdt_arg_spec *arg, int *arg_sz);

static int parse_usdt_spec(struct usdt_spec *spec, const struct usdt_note *note, __u64 usdt_cookie)
{
struct usdt_arg_spec *arg;
const char *s;
int len;
int arg_sz, len;

spec->usdt_cookie = usdt_cookie;
spec->arg_cnt = 0;
Expand All @@ -1159,10 +1160,25 @@ static int parse_usdt_spec(struct usdt_spec *spec, const struct usdt_note *note,
return -E2BIG;
}

len = parse_usdt_arg(s, spec->arg_cnt, &spec->args[spec->arg_cnt]);
arg = &spec->args[spec->arg_cnt];
len = parse_usdt_arg(s, spec->arg_cnt, arg, &arg_sz);
if (len < 0)
return len;

arg->arg_signed = arg_sz < 0;
if (arg_sz < 0)
arg_sz = -arg_sz;

switch (arg_sz) {
case 1: case 2: case 4: case 8:
arg->arg_bitshift = 64 - arg_sz * 8;
break;
default:
pr_warn("usdt: unsupported arg #%d (spec '%s') size: %d\n",
spec->arg_cnt, s, arg_sz);
return -EINVAL;
}

s += len;
spec->arg_cnt++;
}
Expand Down Expand Up @@ -1219,29 +1235,29 @@ static int calc_pt_regs_off(const char *reg_name)
return -ENOENT;
}

static int parse_usdt_arg(const char *arg_str, int arg_num, struct usdt_arg_spec *arg)
static int parse_usdt_arg(const char *arg_str, int arg_num, struct usdt_arg_spec *arg, int *arg_sz)
{
char reg_name[16];
int arg_sz, len, reg_off;
int len, reg_off;
long off;

if (sscanf(arg_str, " %d @ %ld ( %%%15[^)] ) %n", &arg_sz, &off, reg_name, &len) == 3) {
if (sscanf(arg_str, " %d @ %ld ( %%%15[^)] ) %n", arg_sz, &off, reg_name, &len) == 3) {
/* Memory dereference case, e.g., -4@-20(%rbp) */
arg->arg_type = USDT_ARG_REG_DEREF;
arg->val_off = off;
reg_off = calc_pt_regs_off(reg_name);
if (reg_off < 0)
return reg_off;
arg->reg_off = reg_off;
} else if (sscanf(arg_str, " %d @ ( %%%15[^)] ) %n", &arg_sz, reg_name, &len) == 2) {
} else if (sscanf(arg_str, " %d @ ( %%%15[^)] ) %n", arg_sz, reg_name, &len) == 2) {
/* Memory dereference case without offset, e.g., 8@(%rsp) */
arg->arg_type = USDT_ARG_REG_DEREF;
arg->val_off = 0;
reg_off = calc_pt_regs_off(reg_name);
if (reg_off < 0)
return reg_off;
arg->reg_off = reg_off;
} else if (sscanf(arg_str, " %d @ %%%15s %n", &arg_sz, reg_name, &len) == 2) {
} else if (sscanf(arg_str, " %d @ %%%15s %n", arg_sz, reg_name, &len) == 2) {
/* Register read case, e.g., -4@%eax */
arg->arg_type = USDT_ARG_REG;
arg->val_off = 0;
Expand All @@ -1250,7 +1266,7 @@ static int parse_usdt_arg(const char *arg_str, int arg_num, struct usdt_arg_spec
if (reg_off < 0)
return reg_off;
arg->reg_off = reg_off;
} else if (sscanf(arg_str, " %d @ $%ld %n", &arg_sz, &off, &len) == 2) {
} else if (sscanf(arg_str, " %d @ $%ld %n", arg_sz, &off, &len) == 2) {
/* Constant value case, e.g., 4@$71 */
arg->arg_type = USDT_ARG_CONST;
arg->val_off = off;
Expand All @@ -1260,34 +1276,20 @@ static int parse_usdt_arg(const char *arg_str, int arg_num, struct usdt_arg_spec
return -EINVAL;
}

arg->arg_signed = arg_sz < 0;
if (arg_sz < 0)
arg_sz = -arg_sz;

switch (arg_sz) {
case 1: case 2: case 4: case 8:
arg->arg_bitshift = 64 - arg_sz * 8;
break;
default:
pr_warn("usdt: unsupported arg #%d (spec '%s') size: %d\n",
arg_num, arg_str, arg_sz);
return -EINVAL;
}

return len;
}

#elif defined(__s390x__)

/* Do not support __s390__ for now, since user_pt_regs is broken with -m31. */

static int parse_usdt_arg(const char *arg_str, int arg_num, struct usdt_arg_spec *arg)
static int parse_usdt_arg(const char *arg_str, int arg_num, struct usdt_arg_spec *arg, int *arg_sz)
{
unsigned int reg;
int arg_sz, len;
int len;
long off;

if (sscanf(arg_str, " %d @ %ld ( %%r%u ) %n", &arg_sz, &off, &reg, &len) == 3) {
if (sscanf(arg_str, " %d @ %ld ( %%r%u ) %n", arg_sz, &off, &reg, &len) == 3) {
/* Memory dereference case, e.g., -2@-28(%r15) */
arg->arg_type = USDT_ARG_REG_DEREF;
arg->val_off = off;
Expand All @@ -1296,7 +1298,7 @@ static int parse_usdt_arg(const char *arg_str, int arg_num, struct usdt_arg_spec
return -EINVAL;
}
arg->reg_off = offsetof(user_pt_regs, gprs[reg]);
} else if (sscanf(arg_str, " %d @ %%r%u %n", &arg_sz, &reg, &len) == 2) {
} else if (sscanf(arg_str, " %d @ %%r%u %n", arg_sz, &reg, &len) == 2) {
/* Register read case, e.g., -8@%r0 */
arg->arg_type = USDT_ARG_REG;
arg->val_off = 0;
Expand All @@ -1305,7 +1307,7 @@ static int parse_usdt_arg(const char *arg_str, int arg_num, struct usdt_arg_spec
return -EINVAL;
}
arg->reg_off = offsetof(user_pt_regs, gprs[reg]);
} else if (sscanf(arg_str, " %d @ %ld %n", &arg_sz, &off, &len) == 2) {
} else if (sscanf(arg_str, " %d @ %ld %n", arg_sz, &off, &len) == 2) {
/* Constant value case, e.g., 4@71 */
arg->arg_type = USDT_ARG_CONST;
arg->val_off = off;
Expand All @@ -1315,20 +1317,6 @@ static int parse_usdt_arg(const char *arg_str, int arg_num, struct usdt_arg_spec
return -EINVAL;
}

arg->arg_signed = arg_sz < 0;
if (arg_sz < 0)
arg_sz = -arg_sz;

switch (arg_sz) {
case 1: case 2: case 4: case 8:
arg->arg_bitshift = 64 - arg_sz * 8;
break;
default:
pr_warn("usdt: unsupported arg #%d (spec '%s') size: %d\n",
arg_num, arg_str, arg_sz);
return -EINVAL;
}

return len;
}

Expand All @@ -1348,34 +1336,34 @@ static int calc_pt_regs_off(const char *reg_name)
return -ENOENT;
}

static int parse_usdt_arg(const char *arg_str, int arg_num, struct usdt_arg_spec *arg)
static int parse_usdt_arg(const char *arg_str, int arg_num, struct usdt_arg_spec *arg, int *arg_sz)
{
char reg_name[16];
int arg_sz, len, reg_off;
int len, reg_off;
long off;

if (sscanf(arg_str, " %d @ \[ %15[a-z0-9], %ld ] %n", &arg_sz, reg_name, &off, &len) == 3) {
if (sscanf(arg_str, " %d @ \[ %15[a-z0-9] , %ld ] %n", arg_sz, reg_name, &off, &len) == 3) {
/* Memory dereference case, e.g., -4@[sp, 96] */
arg->arg_type = USDT_ARG_REG_DEREF;
arg->val_off = off;
reg_off = calc_pt_regs_off(reg_name);
if (reg_off < 0)
return reg_off;
arg->reg_off = reg_off;
} else if (sscanf(arg_str, " %d @ \[ %15[a-z0-9] ] %n", &arg_sz, reg_name, &len) == 2) {
} else if (sscanf(arg_str, " %d @ \[ %15[a-z0-9] ] %n", arg_sz, reg_name, &len) == 2) {
/* Memory dereference case, e.g., -4@[sp] */
arg->arg_type = USDT_ARG_REG_DEREF;
arg->val_off = 0;
reg_off = calc_pt_regs_off(reg_name);
if (reg_off < 0)
return reg_off;
arg->reg_off = reg_off;
} else if (sscanf(arg_str, " %d @ %ld %n", &arg_sz, &off, &len) == 2) {
} else if (sscanf(arg_str, " %d @ %ld %n", arg_sz, &off, &len) == 2) {
/* Constant value case, e.g., 4@5 */
arg->arg_type = USDT_ARG_CONST;
arg->val_off = off;
arg->reg_off = 0;
} else if (sscanf(arg_str, " %d @ %15[a-z0-9] %n", &arg_sz, reg_name, &len) == 2) {
} else if (sscanf(arg_str, " %d @ %15[a-z0-9] %n", arg_sz, reg_name, &len) == 2) {
/* Register read case, e.g., -8@x4 */
arg->arg_type = USDT_ARG_REG;
arg->val_off = 0;
Expand All @@ -1388,20 +1376,6 @@ static int parse_usdt_arg(const char *arg_str, int arg_num, struct usdt_arg_spec
return -EINVAL;
}

arg->arg_signed = arg_sz < 0;
if (arg_sz < 0)
arg_sz = -arg_sz;

switch (arg_sz) {
case 1: case 2: case 4: case 8:
arg->arg_bitshift = 64 - arg_sz * 8;
break;
default:
pr_warn("usdt: unsupported arg #%d (spec '%s') size: %d\n",
arg_num, arg_str, arg_sz);
return -EINVAL;
}

return len;
}

Expand Down Expand Up @@ -1456,26 +1430,26 @@ static int calc_pt_regs_off(const char *reg_name)
return -ENOENT;
}

static int parse_usdt_arg(const char *arg_str, int arg_num, struct usdt_arg_spec *arg)
static int parse_usdt_arg(const char *arg_str, int arg_num, struct usdt_arg_spec *arg, int *arg_sz)
{
char reg_name[16];
int arg_sz, len, reg_off;
int len, reg_off;
long off;

if (sscanf(arg_str, " %d @ %ld ( %15[a-z0-9] ) %n", &arg_sz, &off, reg_name, &len) == 3) {
if (sscanf(arg_str, " %d @ %ld ( %15[a-z0-9] ) %n", arg_sz, &off, reg_name, &len) == 3) {
/* Memory dereference case, e.g., -8@-88(s0) */
arg->arg_type = USDT_ARG_REG_DEREF;
arg->val_off = off;
reg_off = calc_pt_regs_off(reg_name);
if (reg_off < 0)
return reg_off;
arg->reg_off = reg_off;
} else if (sscanf(arg_str, " %d @ %ld %n", &arg_sz, &off, &len) == 2) {
} else if (sscanf(arg_str, " %d @ %ld %n", arg_sz, &off, &len) == 2) {
/* Constant value case, e.g., 4@5 */
arg->arg_type = USDT_ARG_CONST;
arg->val_off = off;
arg->reg_off = 0;
} else if (sscanf(arg_str, " %d @ %15[a-z0-9] %n", &arg_sz, reg_name, &len) == 2) {
} else if (sscanf(arg_str, " %d @ %15[a-z0-9] %n", arg_sz, reg_name, &len) == 2) {
/* Register read case, e.g., -8@a1 */
arg->arg_type = USDT_ARG_REG;
arg->val_off = 0;
Expand All @@ -1488,26 +1462,12 @@ static int parse_usdt_arg(const char *arg_str, int arg_num, struct usdt_arg_spec
return -EINVAL;
}

arg->arg_signed = arg_sz < 0;
if (arg_sz < 0)
arg_sz = -arg_sz;

switch (arg_sz) {
case 1: case 2: case 4: case 8:
arg->arg_bitshift = 64 - arg_sz * 8;
break;
default:
pr_warn("usdt: unsupported arg #%d (spec '%s') size: %d\n",
arg_num, arg_str, arg_sz);
return -EINVAL;
}

return len;
}

#else

static int parse_usdt_arg(const char *arg_str, int arg_num, struct usdt_arg_spec *arg)
static int parse_usdt_arg(const char *arg_str, int arg_num, struct usdt_arg_spec *arg, int *arg_sz)
{
pr_warn("usdt: libbpf doesn't support USDTs on current architecture\n");
return -ENOTSUP;
Expand Down

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