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Commit 466698e6 authored by Hendrik Brueckner's avatar Hendrik Brueckner Committed by Daniel Borkmann
Browse files

s390/bpf: correct broken uapi for BPF_PROG_TYPE_PERF_EVENT program type 



To mitigate and correct the broken uapi for the BPF_PROG_TYPE_PERF_EVENT
program type, introduce a user_pt_regs structure (similar to arm64) that
exports parts from the beginnig of the pt_regs structure.

The export must start with the beginning of the pt_regs structure because
to correctly calculate BPF prologues for perf (regs_query_register_offset()).

For BPF_PROG_TYPE_PERF_EVENT program types, the BPF program is then passed
a user_pt_regs structure.

Note: Depending on future changes to the s390 pt_regs structure, consider
the user_pt_regs structure to be stable for a particular kernel version
only. (Of course, s390 tries to ensure keep it stable as much as possible.)

Signed-off-by: default avatarHendrik Brueckner <brueckner@linux.vnet.ibm.com>
Reviewed-and-tested-by: default avatarThomas Richter <tmricht@linux.vnet.ibm.com>
Acked-by: default avatarAlexei Starovoitov <ast@kernel.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
parent c895f6f7

arch/s390/include/asm/perf_event.h

+1 −0
Original line number Diff line number Diff line
@@ -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

+8 −3
Original line number Diff line number Diff line
@@ -74,9 +74,14 @@ enum { 
 */

struct pt_regs 

{

	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 → 100644
+9 −0
Original line number Diff line number Diff line 
/* 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__ */

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

+11 −0
Original line number Diff line number Diff line
@@ -290,6 +290,17 @@ typedef struct 
	unsigned long orig_gpr2;

} s390_regs;



/*

 * The user_pt_regs structure exports 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];

} user_pt_regs;



/*

 * Now for the user space program event recording (trace) definitions.

 * The following structures are used only for the ptrace interface, don't