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(I'm so sorry!) Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel os linux
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#include <vmlinux.h>#include <bpf/bpf_core_read.h>#include <bpf/bpf_helpers.h>#include <bpf/bpf_tracing.h>#include "bpf_misc.h"
char _license[] SEC("license") = "GPL";
/* typically virtio scsi has max SGs of 6 */#define VIRTIO_MAX_SGS 6
/* Verifier will fail with SG_MAX = 128. The failure can be * workarounded with a smaller SG_MAX, e.g. 10. */#define WORKAROUND#ifdef WORKAROUND#define SG_MAX 10#else/* typically virtio blk has max SEG of 128 */#define SG_MAX 128#endif
#define SG_CHAIN 0x01UL#define SG_END 0x02UL
#define sg_is_chain(sg) ((sg)->page_link & SG_CHAIN)#define sg_is_last(sg) ((sg)->page_link & SG_END)#define sg_chain_ptr(sg) \ ((struct scatterlist *) ((sg)->page_link & ~(SG_CHAIN | SG_END)))
static inline struct scatterlist *__sg_next(struct scatterlist *sgp){ struct scatterlist sg;
bpf_probe_read_kernel(&sg, sizeof(sg), sgp); if (sg_is_last(&sg)) return NULL;
sgp++;
bpf_probe_read_kernel(&sg, sizeof(sg), sgp); if (sg_is_chain(&sg)) sgp = sg_chain_ptr(&sg);
return sgp;}
static inline struct scatterlist *get_sgp(struct scatterlist **sgs, int i){ struct scatterlist *sgp;
bpf_probe_read_kernel(&sgp, sizeof(sgp), sgs + i); return sgp;}
int run_once = 0;int result = 0;
SEC("kprobe/virtqueue_add_sgs")int BPF_KPROBE(trace_virtqueue_add_sgs, void *unused, struct scatterlist **sgs, unsigned int out_sgs, unsigned int in_sgs){ struct scatterlist *sgp = NULL; __u64 length1 = 0, length2 = 0; unsigned int i, n, len;
if (run_once != 0) return 0;
for (i = 0; (i < VIRTIO_MAX_SGS) && (i < out_sgs); i++) { __sink(out_sgs); for (n = 0, sgp = get_sgp(sgs, i); sgp && (n < SG_MAX); sgp = __sg_next(sgp)) { len = BPF_CORE_READ(sgp, length); length1 += len; n++; } }
for (i = 0; (i < VIRTIO_MAX_SGS) && (i < in_sgs); i++) { __sink(in_sgs); for (n = 0, sgp = get_sgp(sgs, i); sgp && (n < SG_MAX); sgp = __sg_next(sgp)) { len = BPF_CORE_READ(sgp, length); length2 += len; n++; } }
run_once = 1; result = length2 - length1; return 0;}