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2e5c4dd7f8
Currently, there is a problem with tracex2, as it doesn't print the
histogram properly and the results are misleading. (all results report
as 0)
The problem is caused by a change in arguments of the function to which
the kprobe connects. This tracex2 bpf program uses kprobe (attached
to __x64_sys_write) to figure out the size of the write system call. In
order to achieve this, the third argument 'count' must be intact.
The following is a prototype of the sys_write variant. (checked with
pfunct)
~/git/linux$ pfunct -P fs/read_write.o | grep sys_write
ssize_t ksys_write(unsigned int fd, const char * buf, size_t count);
long int __x64_sys_write(const struct pt_regs * regs);
... cross compile with s390x ...
long int __s390_sys_write(struct pt_regs * regs);
Since the nature of SYSCALL_WRAPPER function wraps the argument once,
additional process of argument extraction is required to properly parse
the argument.
#define BPF_KSYSCALL(name, args...)
... snip ...
struct pt_regs *regs = LINUX_HAS_SYSCALL_WRAPPER \
? (struct pt_regs *)PT_REGS_PARM1(ctx) \
: ctx; \
In order to fix this problem, the BPF_SYSCALL macro has been used. This
reduces the hassle of parsing arguments from pt_regs. Since the macro
uses the CORE version of argument extraction, additional portability
comes too.
Signed-off-by: Daniel T. Lee <danieltimlee@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20221224071527.2292-5-danieltimlee@gmail.com
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| .. | ||
| acrn | ||
| auxdisplay | ||
| binderfs | ||
| bpf | ||
| configfs | ||
| connector | ||
| coresight | ||
| fanotify | ||
| fprobe | ||
| ftrace | ||
| hidraw | ||
| hw_breakpoint | ||
| kdb | ||
| kfifo | ||
| kmemleak | ||
| kobject | ||
| kprobes | ||
| landlock | ||
| livepatch | ||
| mei | ||
| nitro_enclaves | ||
| pidfd | ||
| pktgen | ||
| qmi | ||
| rpmsg | ||
| rust | ||
| seccomp | ||
| timers | ||
| trace_events | ||
| trace_printk | ||
| uhid | ||
| user_events | ||
| v4l | ||
| vfio-mdev | ||
| vfs | ||
| watch_queue | ||
| watchdog | ||
| Kconfig | ||
| Makefile | ||