On arm64, the first syscall argument should be accessed via orig_x0
(see arch/arm64/include/asm/syscall.h). Currently regs[0] is used
instead, leading to bpf_syscall_macro test failure.
orig_x0 cannot be added to struct user_pt_regs, since its layout is a
part of the ABI. Therefore provide access to it only through
PT_REGS_PARM1_CORE_SYSCALL() by using a struct pt_regs flavor.
Reported-by: Heiko Carstens <hca@xxxxxxxxxxxxx>
Signed-off-by: Ilya Leoshkevich <iii@xxxxxxxxxxxxx>
---
tools/lib/bpf/bpf_tracing.h | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/tools/lib/bpf/bpf_tracing.h b/tools/lib/bpf/bpf_tracing.h
index f364f1f4710e..928f85f7961c 100644
--- a/tools/lib/bpf/bpf_tracing.h
+++ b/tools/lib/bpf/bpf_tracing.h
@@ -142,8 +142,18 @@
#elif defined(bpf_target_arm64)
+struct pt_regs___arm64 {
+ unsigned long orig_x0;
+} __attribute__((preserve_access_index));
+
/* arm64 provides struct user_pt_regs instead of struct pt_regs to userspace */
#define __PT_REGS_CAST(x) ((const struct user_pt_regs *)(x))
+#define PT_REGS_PARM1_SYSCALL(x) ({ \
+ _Pragma("GCC error \"PT_REGS_PARM1_SYSCALL() is not supported on arm64, use PT_REGS_PARM1_CORE_SYSCALL() instead\""); \
+ 0l; \
+})
+#define PT_REGS_PARM1_CORE_SYSCALL(x) \
+ BPF_CORE_READ((const struct pt_regs___arm64 *)(x), orig_x0)
#define __PT_PARM1_REG regs[0]
#define __PT_PARM2_REG regs[1]
#define __PT_PARM3_REG regs[2]
--
2.34.1
