Merge branch 'bpf-fix-broken-uapi-for-pt-regs'

Hendrik Brueckner says:

====================
Perf tool bpf selftests revealed a broken uapi for s390 and arm64.
With the BPF_PROG_TYPE_PERF_EVENT program type the bpf_perf_event
structure exports the pt_regs structure for all architectures.

This fails for s390 and arm64 because pt_regs are not part of the
user api and kept in-kernel only.  To mitigate the broken uapi,
introduce a wrapper that exports pt_regs in an asm-generic way.
For arm64, export the exising user_pt_regs structure.  For s390,
introduce a user_pt_regs structure that exports the beginning of
pt_regs.

Note that user_pt_regs must export from the beginning of pt_regs
as BPF_PROG_TYPE_PERF_EVENT program type is not the only type for
running BPF programs.

Some more background:

  For the bpf_perf_event, there is a uapi definition that is
  passed to the BPF program.  For other "probe" points like
  trace points, kprobes, and uprobes, there is no uapi and the
  BPF program is always passed pt_regs (which is OK as the BPF
  program runs in the kernel context).  The perf tool can attach
  BPF programs to all of these "probe" points and, optionally,
  can create a BPF prologue to access particular arguments
  (passed as registers).  For this, it uses DWARF/CFI
  information to obtain the register and calls a perf-arch
  backend function, regs_query_register_offset().  This function
  returns the index into (user_)pt_regs for a particular
  register.  Then, perf creates a BPF prologue that accesses
  this register based on the passed stucture from the "probe"
  point.

Part of this series, are also updates to the testing and bpf selftest
to deal with asm-specifics.  To complete the bpf support in perf, the
the regs_query_register_offset function is added for s390 to support
BPF prologue creation.

Changelog v1 -> v2:
- Correct kbuild test bot issues by including
  asm-generic/bpf_perf_event.h for archictectures that do not have
  their own asm version.
- Added patch to clean-up whitespace and coding style issues in s390
  asm/ptrace.h (#4/6) as suggested by Alexei.
====================

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

arch/alpha/include/uapi/asm/Kbuild

@@ -1,2 +1,4 @@
 # UAPI Header export list
 include include/uapi/asm-generic/Kbuild.asm
+
+generic-y += bpf_perf_event.h

arch/arc/include/uapi/asm/Kbuild

@@ -3,6 +3,7 @@ include include/uapi/asm-generic/Kbuild.asm
 
 generic-y += auxvec.h
 generic-y += bitsperlong.h
+generic-y += bpf_perf_event.h
 generic-y += errno.h
 generic-y += fcntl.h
 generic-y += ioctl.h

arch/arm/include/uapi/asm/Kbuild

@@ -7,6 +7,7 @@ generated-y += unistd-oabi.h
 generated-y += unistd-eabi.h
 
 generic-y += bitsperlong.h
+generic-y += bpf_perf_event.h
 generic-y += errno.h
 generic-y += ioctl.h
 generic-y += ipcbuf.h

arch/arm64/include/asm/perf_event.h

@@ -18,6 +18,7 @@
 #define __ASM_PERF_EVENT_H
 
 #include <asm/stack_pointer.h>
+#include <asm/ptrace.h>
 
 #define	ARMV8_PMU_MAX_COUNTERS	32
 #define	ARMV8_PMU_COUNTER_MASK	(ARMV8_PMU_MAX_COUNTERS - 1)
@@ -79,6 +80,7 @@ struct pt_regs;
 extern unsigned long perf_instruction_pointer(struct pt_regs *regs);
 extern unsigned long perf_misc_flags(struct pt_regs *regs);
 #define perf_misc_flags(regs)	perf_misc_flags(regs)
+#define perf_arch_bpf_user_pt_regs(regs) &regs->user_regs
 #endif
 
 #define perf_arch_fetch_caller_regs(regs, __ip) { \

arch/arm64/include/uapi/asm/bpf_perf_event.h

@@ -0,0 +1,9 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _UAPI__ASM_BPF_PERF_EVENT_H__
+#define _UAPI__ASM_BPF_PERF_EVENT_H__
+
+#include <asm/ptrace.h>
+
+typedef struct user_pt_regs bpf_user_pt_regs_t;
+
+#endif /* _UAPI__ASM_BPF_PERF_EVENT_H__ */

arch/blackfin/include/uapi/asm/Kbuild

@@ -3,6 +3,7 @@ include include/uapi/asm-generic/Kbuild.asm
 
 generic-y += auxvec.h
 generic-y += bitsperlong.h
+generic-y += bpf_perf_event.h
 generic-y += errno.h
 generic-y += ioctl.h
 generic-y += ipcbuf.h

arch/c6x/include/uapi/asm/Kbuild

@@ -3,6 +3,7 @@ include include/uapi/asm-generic/Kbuild.asm
 
 generic-y += auxvec.h
 generic-y += bitsperlong.h
+generic-y += bpf_perf_event.h
 generic-y += errno.h
 generic-y += fcntl.h
 generic-y += ioctl.h

arch/cris/include/uapi/asm/Kbuild

@@ -3,6 +3,7 @@ include include/uapi/asm-generic/Kbuild.asm
 
 generic-y += auxvec.h
 generic-y += bitsperlong.h
+generic-y += bpf_perf_event.h
 generic-y += errno.h
 generic-y += fcntl.h
 generic-y += ioctl.h

arch/frv/include/uapi/asm/Kbuild

@@ -1,2 +1,4 @@
 # UAPI Header export list
 include include/uapi/asm-generic/Kbuild.asm
+
+generic-y += bpf_perf_event.h

arch/h8300/include/uapi/asm/Kbuild

@@ -2,6 +2,7 @@
 include include/uapi/asm-generic/Kbuild.asm
 
 generic-y += auxvec.h
+generic-y += bpf_perf_event.h
 generic-y += errno.h
 generic-y += fcntl.h
 generic-y += ioctl.h

arch/hexagon/include/uapi/asm/Kbuild

@@ -2,6 +2,7 @@
 include include/uapi/asm-generic/Kbuild.asm
 
 generic-y += auxvec.h
+generic-y += bpf_perf_event.h
 generic-y += errno.h
 generic-y += fcntl.h
 generic-y += ioctl.h

arch/ia64/include/uapi/asm/Kbuild

@@ -1,4 +1,5 @@
 # UAPI Header export list
 include include/uapi/asm-generic/Kbuild.asm
 
+generic-y += bpf_perf_event.h
 generic-y += kvm_para.h

arch/m32r/include/uapi/asm/Kbuild

@@ -1,5 +1,6 @@
 # UAPI Header export list
 include include/uapi/asm-generic/Kbuild.asm
 
+generic-y += bpf_perf_event.h
 generic-y += kvm_para.h
 generic-y += siginfo.h

arch/m68k/include/uapi/asm/Kbuild

@@ -3,6 +3,7 @@ include include/uapi/asm-generic/Kbuild.asm
 
 generic-y += auxvec.h
 generic-y += bitsperlong.h
+generic-y += bpf_perf_event.h
 generic-y += errno.h
 generic-y += ioctl.h
 generic-y += ipcbuf.h

arch/metag/include/uapi/asm/Kbuild

@@ -3,6 +3,7 @@ include include/uapi/asm-generic/Kbuild.asm
 
 generic-y += auxvec.h
 generic-y += bitsperlong.h
+generic-y += bpf_perf_event.h
 generic-y += errno.h
 generic-y += fcntl.h
 generic-y += ioctl.h

arch/microblaze/include/uapi/asm/Kbuild

@@ -2,6 +2,7 @@
 include include/uapi/asm-generic/Kbuild.asm
 
 generic-y += bitsperlong.h
+generic-y += bpf_perf_event.h
 generic-y += errno.h
 generic-y += fcntl.h
 generic-y += ioctl.h

arch/mips/include/uapi/asm/Kbuild

@@ -1,4 +1,5 @@
 # UAPI Header export list
 include include/uapi/asm-generic/Kbuild.asm
 
+generic-y += bpf_perf_event.h
 generic-y += ipcbuf.h

arch/mn10300/include/uapi/asm/Kbuild

@@ -1,4 +1,5 @@
 # UAPI Header export list
 include include/uapi/asm-generic/Kbuild.asm
 
+generic-y	+= bpf_perf_event.h
 generic-y	+= siginfo.h

arch/nios2/include/uapi/asm/Kbuild

@@ -3,6 +3,7 @@ include include/uapi/asm-generic/Kbuild.asm
 
 generic-y += auxvec.h
 generic-y += bitsperlong.h
+generic-y += bpf_perf_event.h
 generic-y += errno.h
 generic-y += fcntl.h
 generic-y += ioctl.h

arch/openrisc/include/uapi/asm/Kbuild

@@ -3,6 +3,7 @@ include include/uapi/asm-generic/Kbuild.asm
 
 generic-y += auxvec.h
 generic-y += bitsperlong.h
+generic-y += bpf_perf_event.h
 generic-y += errno.h
 generic-y += fcntl.h
 generic-y += ioctl.h

arch/parisc/include/uapi/asm/Kbuild

@@ -2,6 +2,7 @@
 include include/uapi/asm-generic/Kbuild.asm
 
 generic-y += auxvec.h
+generic-y += bpf_perf_event.h
 generic-y += kvm_para.h
 generic-y += param.h
 generic-y += poll.h

arch/powerpc/include/uapi/asm/Kbuild

@@ -1,6 +1,7 @@
 # UAPI Header export list
 include include/uapi/asm-generic/Kbuild.asm
 
+generic-y += bpf_perf_event.h
 generic-y += param.h
 generic-y += poll.h
 generic-y += resource.h

arch/riscv/include/uapi/asm/Kbuild

@@ -3,6 +3,7 @@ include include/uapi/asm-generic/Kbuild.asm
 
 generic-y += setup.h
 generic-y += unistd.h
+generic-y += bpf_perf_event.h
 generic-y += errno.h
 generic-y += fcntl.h
 generic-y += ioctl.h

arch/s390/include/asm/perf_event.h

@@ -40,6 +40,7 @@ struct pt_regs;
 extern unsigned long perf_instruction_pointer(struct pt_regs *regs);
 extern unsigned long perf_misc_flags(struct pt_regs *regs);
 #define perf_misc_flags(regs) perf_misc_flags(regs)
+#define perf_arch_bpf_user_pt_regs(regs) &regs->user_regs
 
 /* Perf pt_regs extension for sample-data-entry indicators */
 struct perf_sf_sde_regs {

arch/s390/include/asm/ptrace.h

@@ -74,9 +74,14 @@ enum {
  */
 struct pt_regs 
 {
-	unsigned long args[1];
-	psw_t psw;
-	unsigned long gprs[NUM_GPRS];
+	union {
+		user_pt_regs user_regs;
+		struct {
+			unsigned long args[1];
+			psw_t psw;
+			unsigned long gprs[NUM_GPRS];
+		};
+	};
 	unsigned long orig_gpr2;
 	unsigned int int_code;
 	unsigned int int_parm;

arch/s390/include/uapi/asm/bpf_perf_event.h

@@ -0,0 +1,9 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _UAPI__ASM_BPF_PERF_EVENT_H__
+#define _UAPI__ASM_BPF_PERF_EVENT_H__
+
+#include <asm/ptrace.h>
+
+typedef user_pt_regs bpf_user_pt_regs_t;
+
+#endif /* _UAPI__ASM_BPF_PERF_EVENT_H__ */