[PATCH bpf-next 2/2] arm64/bpf: Introduce struct user_pt_regs_v2

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

Extending struct user_pt_regs breaks struct bpf_perf_event_data ABI, so
instead of exposing orig_x0 through it, create its copy with orig_x0 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_x0 would be at the same offset as
pt_regs.orig_gpr2.

Fixes: d473f4062165 ("arm64/bpf: Add orig_x0 to user_pt_regs")
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
---
 arch/arm64/include/asm/ptrace.h      | 1 +
 arch/arm64/include/uapi/asm/ptrace.h | 7 +++++++
 tools/lib/bpf/bpf_tracing.h          | 6 ++++--
 3 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/include/asm/ptrace.h b/arch/arm64/include/asm/ptrace.h
index 1be22f7870f8..c5e098af5b70 100644
--- a/arch/arm64/include/asm/ptrace.h
+++ b/arch/arm64/include/asm/ptrace.h
@@ -178,6 +178,7 @@ static inline unsigned long pstate_to_compat_psr(const unsigned long pstate)
 struct pt_regs {
 	union {
 		struct user_pt_regs user_regs;
+		struct user_pt_regs_v2 user_regs_v2;
 		struct {
 			u64 regs[31];
 			u64 sp;
diff --git a/arch/arm64/include/uapi/asm/ptrace.h b/arch/arm64/include/uapi/asm/ptrace.h
index 3c118c5b0893..ab7a2f0cdca8 100644
--- a/arch/arm64/include/uapi/asm/ptrace.h
+++ b/arch/arm64/include/uapi/asm/ptrace.h
@@ -90,6 +90,13 @@ struct user_pt_regs {
 	__u64		sp;
 	__u64		pc;
 	__u64		pstate;
+};
+
+struct user_pt_regs_v2 {
+	__u64		regs[31];
+	__u64		sp;
+	__u64		pc;
+	__u64		pstate;
 	__u64		orig_x0;
 };
 
diff --git a/tools/lib/bpf/bpf_tracing.h b/tools/lib/bpf/bpf_tracing.h
index 76abbc5ff2e8..284cc4d6954e 100644
--- a/tools/lib/bpf/bpf_tracing.h
+++ b/tools/lib/bpf/bpf_tracing.h
@@ -143,8 +143,10 @@
 
 #elif defined(bpf_target_arm64)
 
-/* arm64 provides struct user_pt_regs instead of struct pt_regs to userspace */
-#define __PT_REGS_CAST(x) ((const struct user_pt_regs *)(x))
+/*
+ * arm64 provides struct user_pt_regs_v2 instead of struct pt_regs to userspace
+ */
+#define __PT_REGS_CAST(x) ((const struct user_pt_regs_v2 *)(x))
 #define __PT_PARM1_REG regs[0]
 #define __PT_PARM1_REG_SYSCALL orig_x0
 #define __PT_PARM2_REG regs[1]
-- 
2.34.1