[PATCH bpf-next 3/3] libbpf: Fix accessing the first syscall argument on s390

[Ilya Leoshkevich <iii@xxxxxxxxxxxxx>]

On s390, the first syscall argument should be accessed via orig_gpr2
(see arch/s390/include/asm/syscall.h). Currently gpr[2] is used
instead, leading to bpf_syscall_macro test failure. Fix by adding
__PT_PARM1_REG_SYSCALL macro, similar to the existing
__PT_PARM4_REG_SYSCALL.

Fixes: d084df3b7a4c ("libbpf: Fix the incorrect register read for syscalls on x86_64")
Reported-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
Signed-off-by: Ilya Leoshkevich <iii@xxxxxxxxxxxxx>
---
 tools/lib/bpf/bpf_tracing.h | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/tools/lib/bpf/bpf_tracing.h b/tools/lib/bpf/bpf_tracing.h
index 032ba809f3e5..9d6ff24c7abd 100644
--- a/tools/lib/bpf/bpf_tracing.h
+++ b/tools/lib/bpf/bpf_tracing.h
@@ -117,6 +117,7 @@
 /* s390 provides user_pt_regs instead of struct pt_regs to userspace */
 #define __PT_REGS_CAST(x) ((const user_pt_regs *)(x))
 #define __PT_PARM1_REG gprs[2]
+#define __PT_PARM1_REG_SYSCALL orig_gpr2
 #define __PT_PARM2_REG gprs[3]
 #define __PT_PARM3_REG gprs[4]
 #define __PT_PARM4_REG gprs[5]
@@ -265,7 +266,11 @@ struct pt_regs;
 
 #endif
 
+#ifdef __PT_PARM1_REG_SYSCALL
+#define PT_REGS_PARM1_SYSCALL(x) (__PT_REGS_CAST(x)->__PT_PARM1_REG_SYSCALL)
+#else /* __PT_PARM1_REG_SYSCALL */
 #define PT_REGS_PARM1_SYSCALL(x) PT_REGS_PARM1(x)
+#endif
 #define PT_REGS_PARM2_SYSCALL(x) PT_REGS_PARM2(x)
 #define PT_REGS_PARM3_SYSCALL(x) PT_REGS_PARM3(x)
 #ifdef __PT_PARM4_REG_SYSCALL
@@ -275,7 +280,11 @@ struct pt_regs;
 #endif
 #define PT_REGS_PARM5_SYSCALL(x) PT_REGS_PARM5(x)
 
+#ifdef __PT_PARM1_REG_SYSCALL
+#define PT_REGS_PARM1_CORE_SYSCALL(x) BPF_CORE_READ(__PT_REGS_CAST(x), __PT_PARM1_REG_SYSCALL)
+#else /* __PT_PARM1_REG_SYSCALL */
 #define PT_REGS_PARM1_CORE_SYSCALL(x) PT_REGS_PARM1_CORE(x)
+#endif
 #define PT_REGS_PARM2_CORE_SYSCALL(x) PT_REGS_PARM2_CORE(x)
 #define PT_REGS_PARM3_CORE_SYSCALL(x) PT_REGS_PARM3_CORE(x)
 #ifdef __PT_PARM4_REG_SYSCALL
-- 
2.34.1