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selftests/bpf: Fix an endianness issue in bpf_syscall_macro test 

bpf_syscall_macro reads a long argument into an int variable, which
produces a wrong value on big-endian systems. Fix by reading the
argument into an intermediate long variable first.

Fixes: 77fc0330df ("selftests/bpf: Add a test to confirm PT_REGS_PARM4_SYSCALL")
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220209021745.2215452-2-iii@linux.ibm.com
This commit is contained in:
Ilya Leoshkevich 2022-02-09 03:17:36 +01:00 committed by Andrii Nakryiko
parent cca62426ab
commit 4fc49b51ab
1 changed files with 4 additions and 1 deletions
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5
tools/testing/selftests/bpf/progs/bpf_syscall_macro.c
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@ -28,6 +28,7 @@ int BPF_KPROBE(handle_sys_prctl)
{
struct pt_regs *real_regs;
pid_t pid = bpf_get_current_pid_tgid() >> 32;
unsigned long tmp;
if (pid != filter_pid)
return 0;
@ -35,7 +36,9 @@ int BPF_KPROBE(handle_sys_prctl)
real_regs = (struct pt_regs *)PT_REGS_PARM1(ctx);
/* test for PT_REGS_PARM */
bpf_probe_read_kernel(&arg1, sizeof(arg1), &PT_REGS_PARM1_SYSCALL(real_regs));
bpf_probe_read_kernel(&tmp, sizeof(tmp), &PT_REGS_PARM1_SYSCALL(real_regs));
arg1 = tmp;
bpf_probe_read_kernel(&arg2, sizeof(arg2), &PT_REGS_PARM2_SYSCALL(real_regs));
bpf_probe_read_kernel(&arg3, sizeof(arg3), &PT_REGS_PARM3_SYSCALL(real_regs));
bpf_probe_read_kernel(&arg4_cx, sizeof(arg4_cx), &PT_REGS_PARM4(real_regs));