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: Hendrik Brueckner brueckner@linux.vnet.ibm.com Reviewed-and-tested-by: Thomas Richter tmricht@linux.vnet.ibm.com Cc: Martin Schwidefsky schwidefsky@de.ibm.com Cc: Heiko Carstens heiko.carstens@de.ibm.com Cc: Arnaldo Carvalho de Melo acme@kernel.org Cc: Alexei Starovoitov ast@kernel.org Cc: Daniel Borkmann daniel@iogearbox.net --- arch/s390/include/asm/perf_event.h | 1 + arch/s390/include/asm/ptrace.h | 11 ++++++++--- arch/s390/include/uapi/asm/bpf_perf_event.h | 9 +++++++++ arch/s390/include/uapi/asm/ptrace.h | 11 +++++++++++ 4 files changed, 29 insertions(+), 3 deletions(-) create mode 100644 arch/s390/include/uapi/asm/bpf_perf_event.h
diff --git a/arch/s390/include/asm/perf_event.h b/arch/s390/include/asm/perf_event.h index d6c9d1e..b9c0e36 100644 --- a/arch/s390/include/asm/perf_event.h +++ b/arch/s390/include/asm/perf_event.h @@ -40,6 +40,7 @@ extern ssize_t cpumf_events_sysfs_show(struct device *dev, 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) ®s->user_regs
/* Perf pt_regs extension for sample-data-entry indicators */ struct perf_sf_sde_regs { diff --git a/arch/s390/include/asm/ptrace.h b/arch/s390/include/asm/ptrace.h index a3788da..6f70d81 100644 --- a/arch/s390/include/asm/ptrace.h +++ b/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; diff --git a/arch/s390/include/uapi/asm/bpf_perf_event.h b/arch/s390/include/uapi/asm/bpf_perf_event.h new file mode 100644 index 0000000..cefe7c7 --- /dev/null +++ b/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__ */ diff --git a/arch/s390/include/uapi/asm/ptrace.h b/arch/s390/include/uapi/asm/ptrace.h index 0d23c8f..70f7cb2 100644 --- a/arch/s390/include/uapi/asm/ptrace.h +++ b/arch/s390/include/uapi/asm/ptrace.h @@ -291,6 +291,17 @@ } 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 * touch or even look at it if you don't want to modify the user-space