[PATCH bpf-next 1/2] s390/bpf: Introduce user_pt_regs_v2

[Ilya Leoshkevich <iii@linux.ibm.com>]

Extending user_pt_regs breaks struct bpf_perf_event_data ABI, so
instead of exposing orig_gpr2 through it, create its copy with
orig_gpr2 at the end and use it in libbpf.

The existing members are copy-pasted, so now there are 3 copies in
total. It might be tempting to add a user_pt_regs member to
user_pt_regs_v2 instead, however, there is no guarantee that then
user_pt_regs_v2.orig_gpr2 would be at the same offset as
pt_regs.orig_gpr2.

Fixes: 61f88e88f263 ("s390/bpf: Add orig_gpr2 to user_pt_regs")
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
---
 arch/s390/include/asm/ptrace.h      |  1 +
 arch/s390/include/uapi/asm/ptrace.h | 10 ++++++++--
 tools/lib/bpf/bpf_tracing.h         |  4 ++--
 3 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/arch/s390/include/asm/ptrace.h b/arch/s390/include/asm/ptrace.h
index c8698e643904..1a08f36395e5 100644
--- a/arch/s390/include/asm/ptrace.h
+++ b/arch/s390/include/asm/ptrace.h
@@ -79,6 +79,7 @@ enum {
 struct pt_regs {
 	union {
 		user_pt_regs user_regs;
+		user_pt_regs_v2 user_regs_v2;
 		struct {
 			unsigned long args[1];
 			psw_t psw;
diff --git a/arch/s390/include/uapi/asm/ptrace.h b/arch/s390/include/uapi/asm/ptrace.h
index b3dec603f507..b9405b8f0d47 100644
--- a/arch/s390/include/uapi/asm/ptrace.h
+++ b/arch/s390/include/uapi/asm/ptrace.h
@@ -288,16 +288,22 @@ typedef struct {
 } s390_regs;
 
 /*
- * The user_pt_regs structure exports the beginning of
+ * The user_pt_regs and user_pt_regs_v2 structures export the beginning of
  * the in-kernel pt_regs structure to user space.
  */
 typedef struct {
 	unsigned long args[1];
 	psw_t psw;
 	unsigned long gprs[NUM_GPRS];
-	unsigned long orig_gpr2;
 } user_pt_regs;
 
+typedef struct {
+	unsigned long args[1];
+	psw_t psw;
+	unsigned long gprs[NUM_GPRS];
+	unsigned long orig_gpr2;
+} user_pt_regs_v2;
+
 /*
  * Now for the user space program event recording (trace) definitions.
  * The following structures are used only for the ptrace interface, don't
diff --git a/tools/lib/bpf/bpf_tracing.h b/tools/lib/bpf/bpf_tracing.h
index cf980e54d331..76abbc5ff2e8 100644
--- a/tools/lib/bpf/bpf_tracing.h
+++ b/tools/lib/bpf/bpf_tracing.h
@@ -114,8 +114,8 @@
 
 #elif defined(bpf_target_s390)
 
-/* s390 provides user_pt_regs instead of struct pt_regs to userspace */
-#define __PT_REGS_CAST(x) ((const user_pt_regs *)(x))
+/* s390 provides user_pt_regs_v2 instead of struct pt_regs to userspace */
+#define __PT_REGS_CAST(x) ((const user_pt_regs_v2 *)(x))
 #define __PT_PARM1_REG gprs[2]
 #define __PT_PARM1_REG_SYSCALL orig_gpr2
 #define __PT_PARM2_REG gprs[3]
-- 
2.34.1