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Merge branch 'Support riscv libbpf USDT arg parsing logic'
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Pu Lehui says:

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

patch 1 fix a minor issue where usdt_cookie is cast to 32 bits.
patch 2 add support riscv libbpf USDT argument parsing logic,
both RV32 and RV64 tests have been passed as like follow:

# ./test_progs -t usdt
torvalds#169 usdt:OK
Summary: 1/4 PASSED, 0 SKIPPED, 0 FAILED
====================

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
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@anakryiko
anakryiko committed Apr 20, 2022
2 parents dcf456c + 58ca8b0 commit c7655df
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Showing 3 changed files with 113 additions and 6 deletions.
2 changes: 1 addition & 1 deletion tools/lib/bpf/libbpf.c
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Original file line number Diff line number Diff line change
Expand Up @@ -10993,7 +10993,7 @@ struct bpf_link *bpf_program__attach_usdt(const struct bpf_program *prog,
char resolved_path[512];
struct bpf_object *obj = prog->obj;
struct bpf_link *link;
long usdt_cookie;
__u64 usdt_cookie;
int err;

if (!OPTS_VALID(opts, bpf_uprobe_opts))
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2 changes: 1 addition & 1 deletion tools/lib/bpf/libbpf_internal.h
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Original file line number Diff line number Diff line change
Expand Up @@ -571,6 +571,6 @@ struct bpf_link * usdt_manager_attach_usdt(struct usdt_manager *man,
const struct bpf_program *prog,
pid_t pid, const char *path,
const char *usdt_provider, const char *usdt_name,
long usdt_cookie);
__u64 usdt_cookie);

#endif /* __LIBBPF_LIBBPF_INTERNAL_H */
115 changes: 111 additions & 4 deletions tools/lib/bpf/usdt.c
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Original file line number Diff line number Diff line change
Expand Up @@ -10,6 +10,11 @@
#include <linux/ptrace.h>
#include <linux/kernel.h>

/* s8 will be marked as poison while it's a reg of riscv */
#if defined(__riscv)
#define rv_s8 s8
#endif

#include "bpf.h"
#include "libbpf.h"
#include "libbpf_common.h"
Expand Down Expand Up @@ -557,10 +562,10 @@ static int parse_usdt_note(Elf *elf, const char *path, long base_addr,
GElf_Nhdr *nhdr, const char *data, size_t name_off, size_t desc_off,
struct usdt_note *usdt_note);

static int parse_usdt_spec(struct usdt_spec *spec, const struct usdt_note *note, long usdt_cookie);
static int parse_usdt_spec(struct usdt_spec *spec, const struct usdt_note *note, __u64 usdt_cookie);

static int collect_usdt_targets(struct usdt_manager *man, Elf *elf, const char *path, pid_t pid,
const char *usdt_provider, const char *usdt_name, long usdt_cookie,
const char *usdt_provider, const char *usdt_name, __u64 usdt_cookie,
struct usdt_target **out_targets, size_t *out_target_cnt)
{
size_t off, name_off, desc_off, seg_cnt = 0, lib_seg_cnt = 0, target_cnt = 0;
Expand Down Expand Up @@ -939,7 +944,7 @@ static int allocate_spec_id(struct usdt_manager *man, struct hashmap *specs_hash
struct bpf_link *usdt_manager_attach_usdt(struct usdt_manager *man, const struct bpf_program *prog,
pid_t pid, const char *path,
const char *usdt_provider, const char *usdt_name,
long usdt_cookie)
__u64 usdt_cookie)
{
int i, fd, err, spec_map_fd, ip_map_fd;
LIBBPF_OPTS(bpf_uprobe_opts, opts);
Expand Down Expand Up @@ -1141,7 +1146,7 @@ static int parse_usdt_note(Elf *elf, const char *path, long base_addr,

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

static int parse_usdt_spec(struct usdt_spec *spec, const struct usdt_note *note, long usdt_cookie)
static int parse_usdt_spec(struct usdt_spec *spec, const struct usdt_note *note, __u64 usdt_cookie)
{
const char *s;
int len;
Expand Down Expand Up @@ -1400,6 +1405,108 @@ static int parse_usdt_arg(const char *arg_str, int arg_num, struct usdt_arg_spec
return len;
}

#elif defined(__riscv)

static int calc_pt_regs_off(const char *reg_name)
{
static struct {
const char *name;
size_t pt_regs_off;
} reg_map[] = {
{ "ra", offsetof(struct user_regs_struct, ra) },
{ "sp", offsetof(struct user_regs_struct, sp) },
{ "gp", offsetof(struct user_regs_struct, gp) },
{ "tp", offsetof(struct user_regs_struct, tp) },
{ "a0", offsetof(struct user_regs_struct, a0) },
{ "a1", offsetof(struct user_regs_struct, a1) },
{ "a2", offsetof(struct user_regs_struct, a2) },
{ "a3", offsetof(struct user_regs_struct, a3) },
{ "a4", offsetof(struct user_regs_struct, a4) },
{ "a5", offsetof(struct user_regs_struct, a5) },
{ "a6", offsetof(struct user_regs_struct, a6) },
{ "a7", offsetof(struct user_regs_struct, a7) },
{ "s0", offsetof(struct user_regs_struct, s0) },
{ "s1", offsetof(struct user_regs_struct, s1) },
{ "s2", offsetof(struct user_regs_struct, s2) },
{ "s3", offsetof(struct user_regs_struct, s3) },
{ "s4", offsetof(struct user_regs_struct, s4) },
{ "s5", offsetof(struct user_regs_struct, s5) },
{ "s6", offsetof(struct user_regs_struct, s6) },
{ "s7", offsetof(struct user_regs_struct, s7) },
{ "s8", offsetof(struct user_regs_struct, rv_s8) },
{ "s9", offsetof(struct user_regs_struct, s9) },
{ "s10", offsetof(struct user_regs_struct, s10) },
{ "s11", offsetof(struct user_regs_struct, s11) },
{ "t0", offsetof(struct user_regs_struct, t0) },
{ "t1", offsetof(struct user_regs_struct, t1) },
{ "t2", offsetof(struct user_regs_struct, t2) },
{ "t3", offsetof(struct user_regs_struct, t3) },
{ "t4", offsetof(struct user_regs_struct, t4) },
{ "t5", offsetof(struct user_regs_struct, t5) },
{ "t6", offsetof(struct user_regs_struct, t6) },
};
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)
{
char *reg_name = NULL;
int arg_sz, len, reg_off;
long off;

if (sscanf(arg_str, " %d @ %ld ( %m[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);
free(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 @ %m[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;
reg_off = calc_pt_regs_off(reg_name);
free(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;
}

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)
Expand Down

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