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Commit 02413cab authored by Daniel Borkmann's avatar Daniel Borkmann Committed by David S. Miller
Browse files

bpf, samples: don't zero data when not needed 



Remove the zero initialization in the sample programs where appropriate.
Note that this is an optimization which is now possible, old programs
still doing the zero initialization are just fine as well. Also, make
sure we don't have padding issues when we don't memset() the entire
struct anymore.

Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Acked-by: default avatarAlexei Starovoitov <ast@kernel.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 074f528e

samples/bpf/offwaketime_kern.c

+6 −4
Original line number Diff line number Diff line
@@ -11,7 +11,7 @@ 
#include <linux/version.h>

#include <linux/sched.h>



#define _(P) ({typeof(P) val = 0; bpf_probe_read(&val, sizeof(val), &P); val;})

#define _(P) ({typeof(P) val; bpf_probe_read(&val, sizeof(val), &P); val;})



#define MINBLOCK_US	1
@@ -61,7 +61,7 @@ SEC("kprobe/try_to_wake_up") 
int waker(struct pt_regs *ctx)

{

	struct task_struct *p = (void *) PT_REGS_PARM1(ctx);

	struct wokeby_t woke = {};

	struct wokeby_t woke;

	u32 pid;



	pid = _(p->pid);
@@ -75,17 +75,19 @@ int waker(struct pt_regs *ctx) 


static inline int update_counts(void *ctx, u32 pid, u64 delta)

{

	struct key_t key = {};

	struct wokeby_t *woke;

	u64 zero = 0, *val;

	struct key_t key;



	__builtin_memset(&key.waker, 0, sizeof(key.waker));

	bpf_get_current_comm(&key.target, sizeof(key.target));

	key.tret = bpf_get_stackid(ctx, &stackmap, STACKID_FLAGS);

	key.wret = 0;



	woke = bpf_map_lookup_elem(&wokeby, &pid);

	if (woke) {

		key.wret = woke->ret;

		__builtin_memcpy(&key.waker, woke->name, TASK_COMM_LEN);

		__builtin_memcpy(&key.waker, woke->name, sizeof(key.waker));

		bpf_map_delete_elem(&wokeby, &pid);

	}

samples/bpf/tracex1_kern.c

+1 −3
Original line number Diff line number Diff line
@@ -23,16 +23,14 @@ int bpf_prog1(struct pt_regs *ctx) 
	/* attaches to kprobe netif_receive_skb,

	 * looks for packets on loobpack device and prints them

	 */

	char devname[IFNAMSIZ] = {};

	char devname[IFNAMSIZ];

	struct net_device *dev;

	struct sk_buff *skb;

	int len;



	/* non-portable! works for the given kernel only */

	skb = (struct sk_buff *) PT_REGS_PARM1(ctx);



	dev = _(skb->dev);



	len = _(skb->len);



	bpf_probe_read(devname, sizeof(devname), dev->name);

samples/bpf/tracex2_kern.c

+2 −2
Original line number Diff line number Diff line
@@ -66,7 +66,7 @@ struct hist_key { 
	char comm[16];

	u64 pid_tgid;

	u64 uid_gid;

	u32 index;

	u64 index;

};



struct bpf_map_def SEC("maps") my_hist_map = {
@@ -82,7 +82,7 @@ int bpf_prog3(struct pt_regs *ctx) 
	long write_size = PT_REGS_PARM3(ctx);

	long init_val = 1;

	long *value;

	struct hist_key key = {};

	struct hist_key key;



	key.index = log2l(write_size);

	key.pid_tgid = bpf_get_current_pid_tgid();

samples/bpf/tracex5_kern.c

+3 −3
Original line number Diff line number Diff line
@@ -22,7 +22,7 @@ struct bpf_map_def SEC("maps") progs = { 
SEC("kprobe/seccomp_phase1")

int bpf_prog1(struct pt_regs *ctx)

{

	struct seccomp_data sd = {};

	struct seccomp_data sd;



	bpf_probe_read(&sd, sizeof(sd), (void *)PT_REGS_PARM1(ctx));
@@ -40,7 +40,7 @@ int bpf_prog1(struct pt_regs *ctx) 
/* we jump here when syscall number == __NR_write */

PROG(__NR_write)(struct pt_regs *ctx)

{

	struct seccomp_data sd = {};

	struct seccomp_data sd;



	bpf_probe_read(&sd, sizeof(sd), (void *)PT_REGS_PARM1(ctx));

	if (sd.args[2] == 512) {
@@ -53,7 +53,7 @@ PROG(__NR_write)(struct pt_regs *ctx) 


PROG(__NR_read)(struct pt_regs *ctx)

{

	struct seccomp_data sd = {};

	struct seccomp_data sd;



	bpf_probe_read(&sd, sizeof(sd), (void *)PT_REGS_PARM1(ctx));

	if (sd.args[2] > 128 && sd.args[2] <= 1024) {