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Fprobe store its data structure address and size on the fgraph return stack by __fprobe_header. But most 64bit architecture can combine those to one unsigned long value because 4 MSB in the kernel address are the same. With this encoding, fprobe can consume less space on ret_stack. This introduces asm/fprobe.h to define arch dependent encode/decode macros. Note that since fprobe depends on CONFIG_HAVE_FUNCTION_GRAPH_FREGS, currently only arm64, loongarch, riscv, s390 and x86 are supported. Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> Acked-by: Heiko Carstens <hca@linux.ibm.com> # s390 Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com> Cc: Florent Revest <revest@chromium.org> Cc: Martin KaFai Lau <martin.lau@linux.dev> Cc: bpf <bpf@vger.kernel.org> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Alan Maguire <alan.maguire@oracle.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Heiko Carstens <hca@linux.ibm.com> Cc: Will Deacon <will@kernel.org> Cc: Huacai Chen <chenhuacai@kernel.org> Cc: WANG Xuerui <kernel@xen0n.name> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Alexander Gordeev <agordeev@linux.ibm.com> Cc: Christian Borntraeger <borntraeger@linux.ibm.com> Cc: Sven Schnelle <svens@linux.ibm.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: x86@kernel.org Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Link: https://lore.kernel.org/173519005783.391279.5307910947400277525.stgit@devnote2 Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
47 lines
1.4 KiB
C
47 lines
1.4 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* Generic arch dependent fprobe macros.
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*/
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#ifndef __ASM_GENERIC_FPROBE_H__
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#define __ASM_GENERIC_FPROBE_H__
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#include <linux/bits.h>
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#ifdef CONFIG_64BIT
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/*
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* Encoding the size and the address of fprobe into one 64bit entry.
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* The 32bit architectures should use 2 entries to store those info.
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*/
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#define ARCH_DEFINE_ENCODE_FPROBE_HEADER
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#define FPROBE_HEADER_MSB_SIZE_SHIFT (BITS_PER_LONG - FPROBE_DATA_SIZE_BITS)
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#define FPROBE_HEADER_MSB_MASK \
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GENMASK(FPROBE_HEADER_MSB_SIZE_SHIFT - 1, 0)
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/*
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* By default, this expects the MSBs in the address of kprobe is 0xf.
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* If any arch needs another fixed pattern (e.g. s390 is zero filled),
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* override this.
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*/
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#define FPROBE_HEADER_MSB_PATTERN \
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GENMASK(BITS_PER_LONG - 1, FPROBE_HEADER_MSB_SIZE_SHIFT)
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#define arch_fprobe_header_encodable(fp) \
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(((unsigned long)(fp) & ~FPROBE_HEADER_MSB_MASK) == \
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FPROBE_HEADER_MSB_PATTERN)
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#define arch_encode_fprobe_header(fp, size) \
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(((unsigned long)(fp) & FPROBE_HEADER_MSB_MASK) | \
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((unsigned long)(size) << FPROBE_HEADER_MSB_SIZE_SHIFT))
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#define arch_decode_fprobe_header_size(val) \
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((unsigned long)(val) >> FPROBE_HEADER_MSB_SIZE_SHIFT)
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#define arch_decode_fprobe_header_fp(val) \
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((struct fprobe *)(((unsigned long)(val) & FPROBE_HEADER_MSB_MASK) | \
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FPROBE_HEADER_MSB_PATTERN))
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#endif /* CONFIG_64BIT */
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#endif /* __ASM_GENERIC_FPROBE_H__ */
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