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Merge branch 'libbpf: usdt arm arg parsing support'
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Puranjay Mohan says:

====================

This series add the support of the ARM architecture to libbpf USDT. This
involves implementing the parse_usdt_arg() function for ARM.

It was seen that the last part of parse_usdt_arg() is repeated for all architectures,
so, the first patch in this series refactors these functions and moved the post
processing to parse_usdt_spec()

Changes in V2[1] to V3:

- Use a tabular approach to find register offsets.
- Add the patch for refactoring parse_usdt_arg()
====================

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
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Andrii Nakryiko committed Mar 7, 2023
2 parents 3ecde21 + 720d93b commit d1d51a6
Showing 1 changed file with 118 additions and 78 deletions.
196 changes: 118 additions & 78 deletions tools/lib/bpf/usdt.c
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Original file line number Diff line number Diff line change
@@ -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;
@@ -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++;
}
@@ -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;
@@ -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;
@@ -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;
@@ -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;
@@ -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;
@@ -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;
}

@@ -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;
@@ -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;
}

@@ -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;
@@ -1488,17 +1462,83 @@ 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;
return len;
}

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);
#elif defined(__arm__)

static int calc_pt_regs_off(const char *reg_name)
{
static struct {
const char *name;
size_t pt_regs_off;
} reg_map[] = {
{ "r0", offsetof(struct pt_regs, uregs[0]) },
{ "r1", offsetof(struct pt_regs, uregs[1]) },
{ "r2", offsetof(struct pt_regs, uregs[2]) },
{ "r3", offsetof(struct pt_regs, uregs[3]) },
{ "r4", offsetof(struct pt_regs, uregs[4]) },
{ "r5", offsetof(struct pt_regs, uregs[5]) },
{ "r6", offsetof(struct pt_regs, uregs[6]) },
{ "r7", offsetof(struct pt_regs, uregs[7]) },
{ "r8", offsetof(struct pt_regs, uregs[8]) },
{ "r9", offsetof(struct pt_regs, uregs[9]) },
{ "r10", offsetof(struct pt_regs, uregs[10]) },
{ "fp", offsetof(struct pt_regs, uregs[11]) },
{ "ip", offsetof(struct pt_regs, uregs[12]) },
{ "sp", offsetof(struct pt_regs, uregs[13]) },
{ "lr", offsetof(struct pt_regs, uregs[14]) },
{ "pc", offsetof(struct pt_regs, uregs[15]) },
};
int i;

for (i = 0; i < ARRAY_SIZE(reg_map); i++) {
if (strcmp(reg_name, reg_map[i].name) == 0)
return reg_map[i].pt_regs_off;
}

pr_warn("usdt: unrecognized register '%s'\n", reg_name);
return -ENOENT;
}

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 len, reg_off;
long off;

if (sscanf(arg_str, " %d @ \[ %15[a-z0-9] , #%ld ] %n",
arg_sz, reg_name, &off, &len) == 3) {
/* Memory dereference case, e.g., -4@[fp, #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) {
/* 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) {
/* 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) {
/* Register read case, e.g., -8@r4 */
arg->arg_type = USDT_ARG_REG;
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 {
pr_warn("usdt: unrecognized arg #%d spec '%s'\n", arg_num, arg_str);
return -EINVAL;
}

@@ -1507,7 +1547,7 @@ static int parse_usdt_arg(const char *arg_str, int arg_num, struct usdt_arg_spec

#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;

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