Commit 700a6ef1 authored by Andrii Nakryiko's avatar Andrii Nakryiko
Browse files

Merge branch 'Add USDT support for s390' 



Ilya Leoshkevich says:

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

This series adds USDT support for s390, making the "usdt" test pass
there. Patch 1 is a collection of minor cleanups, patch 2 adds
BPF-side support, patch 3 adds userspace-side support.
====================

Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
parents ded6dffa bd022685

tools/lib/bpf/usdt.bpf.h

+5 −2
Original line number Diff line number Diff line
@@ -166,7 +166,7 @@ int bpf_usdt_arg(struct pt_regs *ctx, __u64 arg_num, long *res) 
	case BPF_USDT_ARG_REG_DEREF:

		/* Arg is in memory addressed by register, plus some offset

		 * (e.g., "-4@-1204(%rbp)" in USDT arg spec). Register is

		 * identified lik with BPF_USDT_ARG_REG case, and the offset

		 * identified like with BPF_USDT_ARG_REG case, and the offset

		 * is in arg_spec->val_off. We first fetch register contents

		 * from pt_regs, then do another user-space probe read to

		 * fetch argument value itself.
@@ -177,6 +177,9 @@ int bpf_usdt_arg(struct pt_regs *ctx, __u64 arg_num, long *res) 
		err = bpf_probe_read_user(&val, sizeof(val), (void *)val + arg_spec->val_off);

		if (err)

			return err;

#if __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__

		val >>= arg_spec->arg_bitshift;

#endif

		break;

	default:

		return -EINVAL;
@@ -198,7 +201,7 @@ int bpf_usdt_arg(struct pt_regs *ctx, __u64 arg_num, long *res) 
/* Retrieve user-specified cookie value provided during attach as

 * bpf_usdt_opts.usdt_cookie. This serves the same purpose as BPF cookie

 * returned by bpf_get_attach_cookie(). Libbpf's support for USDT is itself

 * utilizaing BPF cookies internally, so user can't use BPF cookie directly

 * utilizing BPF cookies internally, so user can't use BPF cookie directly

 * for USDT programs and has to use bpf_usdt_cookie() API instead.

 */

static inline __noinline

tools/lib/bpf/usdt.c

+61 −6
Original line number Diff line number Diff line
@@ -108,7 +108,7 @@ 
 * code through spec map. This allows BPF applications to quickly fetch the

 * actual value at runtime using a simple BPF-side code.

 *

 * With basics out of the way, let's go over less immeditately obvious aspects

 * With basics out of the way, let's go over less immediately obvious aspects

 * of supporting USDTs.

 *

 * First, there is no special USDT BPF program type. It is actually just
@@ -189,14 +189,14 @@ 
#define USDT_NOTE_TYPE 3

#define USDT_NOTE_NAME "stapsdt"



/* should match exactly enum __bpf_usdt_arg_type from bpf_usdt.bpf.h */

/* should match exactly enum __bpf_usdt_arg_type from usdt.bpf.h */

enum usdt_arg_type {

	USDT_ARG_CONST,

	USDT_ARG_REG,

	USDT_ARG_REG_DEREF,

};



/* should match exactly struct __bpf_usdt_arg_spec from bpf_usdt.bpf.h */

/* should match exactly struct __bpf_usdt_arg_spec from usdt.bpf.h */

struct usdt_arg_spec {

	__u64 val_off;

	enum usdt_arg_type arg_type;
@@ -328,9 +328,9 @@ static int sanity_check_usdt_elf(Elf *elf, const char *path) 
		return -EBADF;

	}



#if __BYTE_ORDER == __LITTLE_ENDIAN

#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__

	endianness = ELFDATA2LSB;

#elif __BYTE_ORDER == __BIG_ENDIAN

#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__

	endianness = ELFDATA2MSB;

#else

# error "Unrecognized __BYTE_ORDER__"
@@ -843,7 +843,7 @@ static int bpf_link_usdt_detach(struct bpf_link *link) 
						   sizeof(*new_free_ids));

		/* If we couldn't resize free_spec_ids, we'll just leak

		 * a bunch of free IDs; this is very unlikely to happen and if

		 * system is so exausted on memory, it's the least of user's

		 * system is so exhausted on memory, it's the least of user's

		 * concerns, probably.

		 * So just do our best here to return those IDs to usdt_manager.

		 */
@@ -1269,6 +1269,61 @@ static int parse_usdt_arg(const char *arg_str, int arg_num, struct usdt_arg_spec 
	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)

{

	unsigned int reg;

	int arg_sz, len;

	long off;



	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;

		if (reg > 15) {

			pr_warn("usdt: unrecognized register '%%r%u'\n", reg);

			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) {

		/* Register read case, e.g., -8@%r0 */

		arg->arg_type = USDT_ARG_REG;

		arg->val_off = 0;

		if (reg > 15) {

			pr_warn("usdt: unrecognized register '%%r%u'\n", reg);

			return -EINVAL;

		}

		arg->reg_off = offsetof(user_pt_regs, gprs[reg]);

	} 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;

		arg->reg_off = 0;

	} 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)