From: Masami Hiramatsu (Google) <[email protected]> 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) <[email protected]> Cc: Catalin Marinas <[email protected]> Cc: Will Deacon <[email protected]> Cc: Huacai Chen <[email protected]> Cc: WANG Xuerui <[email protected]> Cc: Paul Walmsley <[email protected]> Cc: Palmer Dabbelt <[email protected]> Cc: Albert Ou <[email protected]> Cc: Heiko Carstens <[email protected]> Cc: Vasily Gorbik <[email protected]> Cc: Alexander Gordeev <[email protected]> Cc: Christian Borntraeger <[email protected]> Cc: Sven Schnelle <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Dave Hansen <[email protected]> Cc: [email protected] Cc: "H. Peter Anvin" <[email protected]> Cc: Arnd Bergmann <[email protected]> Cc: Steven Rostedt <[email protected]> Cc: Masami Hiramatsu <[email protected]> Cc: Mathieu Desnoyers <[email protected]> --- arch/arm64/include/asm/fprobe.h | 7 +++++++ arch/loongarch/include/asm/fprobe.h | 5 +++++ arch/riscv/include/asm/fprobe.h | 9 +++++++++ arch/s390/include/asm/fprobe.h | 10 ++++++++++ arch/x86/include/asm/fprobe.h | 9 +++++++++ include/asm-generic/fprobe.h | 33 +++++++++++++++++++++++++++++++++ kernel/trace/fprobe.c | 29 +++++++++++++++++++++++++++++ 7 files changed, 102 insertions(+) create mode 100644 arch/arm64/include/asm/fprobe.h create mode 100644 arch/loongarch/include/asm/fprobe.h create mode 100644 arch/riscv/include/asm/fprobe.h create mode 100644 arch/s390/include/asm/fprobe.h create mode 100644 arch/x86/include/asm/fprobe.h create mode 100644 include/asm-generic/fprobe.h diff --git a/arch/arm64/include/asm/fprobe.h b/arch/arm64/include/asm/fprobe.h new file mode 100644 index 000000000000..bbf254db878d --- /dev/null +++ b/arch/arm64/include/asm/fprobe.h @@ -0,0 +1,7 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _ASM_ARM64_FPROBE_H +#define _ASM_ARM64_FPROBE_H + +#include <asm-generic/fprobe.h> + +#endif /* _ASM_ARM64_FPROBE_H */ \ No newline at end of file diff --git a/arch/loongarch/include/asm/fprobe.h b/arch/loongarch/include/asm/fprobe.h new file mode 100644 index 000000000000..68156a66873c --- /dev/null +++ b/arch/loongarch/include/asm/fprobe.h @@ -0,0 +1,5 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _ASM_LOONGARCH_FPROBE_H +#define _ASM_LOONGARCH_FPROBE_H + +#endif /* _ASM_LOONGARCH_FPROBE_H */ \ No newline at end of file diff --git a/arch/riscv/include/asm/fprobe.h b/arch/riscv/include/asm/fprobe.h new file mode 100644 index 000000000000..51fc2ef3eda1 --- /dev/null +++ b/arch/riscv/include/asm/fprobe.h @@ -0,0 +1,9 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _ASM_RISCV_FPROBE_H +#define _ASM_RISCV_FPROBE_H + +#ifdef CONFIG_64BIT +#include <asm-generic/fprobe.h> +#endif + +#endif /* _ASM_RISCV_FPROBE_H */ \ No newline at end of file diff --git a/arch/s390/include/asm/fprobe.h b/arch/s390/include/asm/fprobe.h new file mode 100644 index 000000000000..84b94ba6e3a4 --- /dev/null +++ b/arch/s390/include/asm/fprobe.h @@ -0,0 +1,10 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _ASM_S390_FPROBE_H +#define _ASM_S390_FPROBE_H + +#include <asm-generic/fprobe.h> + +#undef FPROBE_HEADER_MSB_PATTERN +#define FPROBE_HEADER_MSB_PATTERN 0 + +#endif /* _ASM_S390_FPROBE_H */ \ No newline at end of file diff --git a/arch/x86/include/asm/fprobe.h b/arch/x86/include/asm/fprobe.h new file mode 100644 index 000000000000..c863518bef90 --- /dev/null +++ b/arch/x86/include/asm/fprobe.h @@ -0,0 +1,9 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _ASM_X86_FPROBE_H +#define _ASM_X86_FPROBE_H + +#ifdef CONFIG_64BIT +#include <asm-generic/fprobe.h> +#endif + +#endif /* _ASM_X86_FPROBE_H */ \ No newline at end of file diff --git a/include/asm-generic/fprobe.h b/include/asm-generic/fprobe.h new file mode 100644 index 000000000000..00f480748a1d --- /dev/null +++ b/include/asm-generic/fprobe.h @@ -0,0 +1,33 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * linux/include/asm-generic/fprobe.h + */ +#ifndef __ASM_GENERIC_FPROBE_H__ +#define __ASM_GENERIC_FPROBE_H__ + +#include <linux/bits.h> + +#define ARCH_HAVE_ENCODE_FPROBE_HEADER + +#define FPROBE_HEADER_MSB_SIZE_SHIFT (BITS_PER_LONG - FPROBE_DATA_SIZE_BITS) +#define FPROBE_HEADER_MSB_MASK \ + GENMASK(FPROBE_HEADER_MSB_SIZE_SHIFT - 1, 0) +#define FPROBE_HEADER_MSB_PATTERN \ + GENMASK(BITS_PER_LONG - 1, FPROBE_HEADER_MSB_SIZE_SHIFT) + +#define arch_fprobe_header_encodable(fp) \ + (((unsigned long)(fp) & ~FPROBE_HEADER_MSB_MASK) == \ + FPROBE_HEADER_MSB_PATTERN) + +#define arch_encode_fprobe_header(fp, size) \ + ((unsigned long)(fp) & FPROBE_HEADER_MSB_MASK) | \ + ((unsigned long)(size) << FPROBE_HEADER_MSB_SIZE_SHIFT) + +#define arch_decode_fprobe_header_size(val) \ + ((unsigned long)(val) >> FPROBE_HEADER_MSB_SIZE_SHIFT) + +#define arch_decode_fprobe_header_fp(val) \ + (struct fprobe *)(((unsigned long)(val) & FPROBE_HEADER_MSB_MASK) | \ + FPROBE_HEADER_MSB_PATTERN) + +#endif /* __ASM_GENERIC_FPROBE_H__ */ \ No newline at end of file diff --git a/kernel/trace/fprobe.c b/kernel/trace/fprobe.c index ed9c1d79426a..949963f1f17a 100644 --- a/kernel/trace/fprobe.c +++ b/kernel/trace/fprobe.c @@ -13,6 +13,8 @@ #include <linux/slab.h> #include <linux/sort.h> +#include <asm/fprobe.h> + #include "trace.h" #define FPROBE_IP_HASH_BITS 8 @@ -143,6 +145,31 @@ static int del_fprobe_hash(struct fprobe *fp) return 0; } +#ifdef ARCH_HAVE_ENCODE_FPROBE_HEADER + +/* The arch should encode fprobe_header info into one unsigned long */ +#define FPROBE_HEADER_SIZE_IN_LONG 1 + +static inline bool write_fprobe_header(unsigned long *stack, + struct fprobe *fp, unsigned int size_words) +{ + if (WARN_ON_ONCE(size_words > MAX_FPROBE_DATA_SIZE_WORD || + !arch_fprobe_header_encodable(fp))) + return false; + + *stack = arch_encode_fprobe_header(fp, size_words); + return true; +} + +static inline void read_fprobe_header(unsigned long *stack, + struct fprobe **fp, unsigned int *size_words) +{ + *fp = arch_decode_fprobe_header_fp(*stack); + *size_words = arch_decode_fprobe_header_size(*stack); +} + +#else + /* Generic fprobe_header */ struct __fprobe_header { struct fprobe *fp; @@ -173,6 +200,8 @@ static inline void read_fprobe_header(unsigned long *stack, *size_words = fph->size_words; } +#endif + /* * fprobe shadow stack management: * Since fprobe shares a single fgraph_ops, it needs to share the stack entry
