lwn.git/arch/arm64/include/asm/insn.h, branch standardize-docs

arm64: Prevent cpu hotplug rwsem recursion

2017-05-26T08:10:45+00:00

The text patching functions which are invoked from jump_label and kprobes code are protected against cpu hotplug at the call sites. Use stop_machine_cpuslocked() to avoid recursion on the cpu hotplug rwsem. stop_machine_cpuslocked() contains a lockdep assertion to catch any unprotected callers. Signed-off-by: Thomas Gleixner Acked-by: Ingo Molnar Cc: Paul E. McKenney Cc: Mark Rutland Cc: Peter Zijlstra Cc: Catalin Marinas Cc: Sebastian Siewior Cc: Will Deacon Cc: Steven Rostedt Cc: linux-arm-kernel@lists.infradead.org Link: http://lkml.kernel.org/r/20170524081549.197070135@linutronix.de

bpf, arm64: implement jiting of BPF_XADD

2017-05-02T19:04:50+00:00

This work adds BPF_XADD for BPF_W/BPF_DW to the arm64 JIT and therefore completes JITing of all BPF instructions, meaning we can thus also remove the 'notyet' label and do not need to fall back to the interpreter when BPF_XADD is used in a program! This now also brings arm64 JIT in line with x86_64, s390x, ppc64, sparc64, where all current eBPF features are supported. BPF_W example from test_bpf: .u.insns_int = { BPF_ALU32_IMM(BPF_MOV, R0, 0x12), BPF_ST_MEM(BPF_W, R10, -40, 0x10), BPF_STX_XADD(BPF_W, R10, R0, -40), BPF_LDX_MEM(BPF_W, R0, R10, -40), BPF_EXIT_INSN(), }, [...] 00000020: 52800247 mov w7, #0x12 // #18 00000024: 928004eb mov x11, #0xffffffffffffffd8 // #-40 00000028: d280020a mov x10, #0x10 // #16 0000002c: b82b6b2a str w10, [x25,x11] // start of xadd mapping: 00000030: 928004ea mov x10, #0xffffffffffffffd8 // #-40 00000034: 8b19014a add x10, x10, x25 00000038: f9800151 prfm pstl1strm, [x10] 0000003c: 885f7d4b ldxr w11, [x10] 00000040: 0b07016b add w11, w11, w7 00000044: 880b7d4b stxr w11, w11, [x10] 00000048: 35ffffab cbnz w11, 0x0000003c // end of xadd mapping: [...] BPF_DW example from test_bpf: .u.insns_int = { BPF_ALU32_IMM(BPF_MOV, R0, 0x12), BPF_ST_MEM(BPF_DW, R10, -40, 0x10), BPF_STX_XADD(BPF_DW, R10, R0, -40), BPF_LDX_MEM(BPF_DW, R0, R10, -40), BPF_EXIT_INSN(), }, [...] 00000020: 52800247 mov w7, #0x12 // #18 00000024: 928004eb mov x11, #0xffffffffffffffd8 // #-40 00000028: d280020a mov x10, #0x10 // #16 0000002c: f82b6b2a str x10, [x25,x11] // start of xadd mapping: 00000030: 928004ea mov x10, #0xffffffffffffffd8 // #-40 00000034: 8b19014a add x10, x10, x25 00000038: f9800151 prfm pstl1strm, [x10] 0000003c: c85f7d4b ldxr x11, [x10] 00000040: 8b07016b add x11, x11, x7 00000044: c80b7d4b stxr w11, x11, [x10] 00000048: 35ffffab cbnz w11, 0x0000003c // end of xadd mapping: [...] Tested on Cavium ThunderX ARMv8, test suite results after the patch: No JIT: [ 3751.855362] test_bpf: Summary: 311 PASSED, 0 FAILED, [0/303 JIT'ed] With JIT: [ 3573.759527] test_bpf: Summary: 311 PASSED, 0 FAILED, [303/303 JIT'ed] Signed-off-by: Daniel Borkmann Acked-by: Alexei Starovoitov Signed-off-by: David S. Miller

arm64: Add helper to decode register from instruction

2017-01-10T17:11:23+00:00

Add a helper to extract the register field from a given instruction. Cc: Catalin Marinas Cc: Will Deacon Cc: Mark Rutland Reviewed-by: Catalin Marinas Signed-off-by: Suzuki K Poulose Signed-off-by: Will Deacon

arm64: insn: Add helpers for adrp offsets

2016-09-09T14:03:28+00:00

Adds helpers for decoding/encoding the PC relative addresses for adrp. This will be used for handling dynamic patching of 'adrp' instructions in alternative code patching. Cc: Mark Rutland Cc: Will Deacon Cc: Catalin Marinas Cc: Marc Zyngier Signed-off-by: Suzuki K Poulose Signed-off-by: Will Deacon

arm64: Kprobes with single stepping support

2016-07-19T14:03:20+00:00

Add support for basic kernel probes(kprobes) and jump probes (jprobes) for ARM64. Kprobes utilizes software breakpoint and single step debug exceptions supported on ARM v8. A software breakpoint is placed at the probe address to trap the kernel execution into the kprobe handler. ARM v8 supports enabling single stepping before the break exception return (ERET), with next PC in exception return address (ELR_EL1). The kprobe handler prepares an executable memory slot for out-of-line execution with a copy of the original instruction being probed, and enables single stepping. The PC is set to the out-of-line slot address before the ERET. With this scheme, the instruction is executed with the exact same register context except for the PC (and DAIF) registers. Debug mask (PSTATE.D) is enabled only when single stepping a recursive kprobe, e.g.: during kprobes reenter so that probed instruction can be single stepped within the kprobe handler -exception- context. The recursion depth of kprobe is always 2, i.e. upon probe re-entry, any further re-entry is prevented by not calling handlers and the case counted as a missed kprobe). Single stepping from the x-o-l slot has a drawback for PC-relative accesses like branching and symbolic literals access as the offset from the new PC (slot address) may not be ensured to fit in the immediate value of the opcode. Such instructions need simulation, so reject probing them. Instructions generating exceptions or cpu mode change are rejected for probing. Exclusive load/store instructions are rejected too. Additionally, the code is checked to see if it is inside an exclusive load/store sequence (code from Pratyush). System instructions are mostly enabled for stepping, except MSR/MRS accesses to "DAIF" flags in PSTATE, which are not safe for probing. This also changes arch/arm64/include/asm/ptrace.h to use include/asm-generic/ptrace.h. Thanks to Steve Capper and Pratyush Anand for several suggested Changes. Signed-off-by: Sandeepa Prabhu Signed-off-by: David A. Long Signed-off-by: Pratyush Anand Acked-by: Masami Hiramatsu Signed-off-by: Catalin Marinas

arm64: add conditional instruction simulation support

2016-07-19T14:03:19+00:00

Cease using the arm32 arm_check_condition() function and replace it with a local version for use in deprecated instruction support on arm64. Also make the function table used by this available for future use by kprobes and/or uprobes. This function is derived from code written by Sandeepa Prabhu. Signed-off-by: Sandeepa Prabhu Signed-off-by: David A. Long Acked-by: Masami Hiramatsu Signed-off-by: Catalin Marinas

arm64: Add more test functions to insn.c

2016-07-19T14:03:19+00:00

Certain instructions are hard to execute correctly out-of-line (as in kprobes). Test functions are added to insn.[hc] to identify these. The instructions include any that use PC-relative addressing, change the PC, or change interrupt masking. For efficiency and simplicity test functions are also added for small collections of related instructions. Signed-off-by: David A. Long Acked-by: Masami Hiramatsu Signed-off-by: Catalin Marinas

arm64: insn: Add aarch64_{get,set}_branch_offset

2015-06-03T14:43:24+00:00

In order to deal with branches located in alternate sequences, but pointing to the main kernel text, it is required to extract the relative displacement encoded in the instruction, and to be able to update said instruction with a new offset (once it is known). For this, we introduce three new helpers: - aarch64_insn_is_branch_imm is a predicate indicating if the instruction is an immediate branch - aarch64_get_branch_offset returns a signed value representing the byte offset encoded in a branch instruction - aarch64_set_branch_offset takes an instruction and an offset, and returns the corresponding updated instruction. Acked-by: Will Deacon Signed-off-by: Marc Zyngier Signed-off-by: Catalin Marinas

arm64: insn: Add aarch64_insn_decode_immediate

2015-03-30T10:03:42+00:00

Patching an instruction sometimes requires extracting the immediate field from this instruction. To facilitate this, and avoid potential duplication of code, add aarch64_insn_decode_immediate as the reciprocal to aarch64_insn_encode_immediate. Acked-by: Will Deacon Signed-off-by: Marc Zyngier Signed-off-by: Will Deacon

arm64: insn: fix compare-and-branch encodings

2015-02-23T09:13:45+00:00

Fix cbz/cbnz having the mask offset by a bit, and add encodings for tbz/tbnz so that all branch forms are represented. Signed-off-by: Robin Murphy Acked-by: Will Deacon Acked-by: Zi Shen Lim Signed-off-by: Will Deacon