From: Mark Rutland Date: Mon, 14 Nov 2022 13:59:27 +0000 (+0000) Subject: arm64: insn: simplify insn group identification X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=4488f90c8609e5c420531d604dd19cdfee4ec0e0;p=linux.git arm64: insn: simplify insn group identification The only code which needs to check for an entire instruction group is the aarch64_insn_is_steppable() helper function used by kprobes, which must not be instrumented, and only needs to check for the "Branch, exception generation and system instructions" class. Currently we have an out-of-line helper in insn.c which must be marked as __kprobes, which indexes a table with some bits extracted from the instruction. In aarch64_insn_is_steppable() we then need to compare the result with an expected enum value. It would be simpler to have a predicate for this, as with the other aarch64_insn_is_*() helpers, which would be always inlined to prevent inadvertent instrumentation, and would permit better code generation. This patch adds a predicate function for this instruction group using the existing __AARCH64_INSN_FUNCS() helpers, and removes the existing out-of-line helper. As the only class we currently care about is the branch+exception+sys class, I have only added helpers for this, and left the other classes unimplemented for now. There should be no functional change as a result of this patch. Signed-off-by: Mark Rutland Cc: Catalin Marinas Cc: Joey Gouly Cc: Will Deacon Reviewed-by: Joey Gouly Link: https://lore.kernel.org/r/20221114135928.3000571-4-mark.rutland@arm.com Signed-off-by: Will Deacon --- diff --git a/arch/arm64/include/asm/insn.h b/arch/arm64/include/asm/insn.h index de5bc71b4b1dc..876cacad103e2 100644 --- a/arch/arm64/include/asm/insn.h +++ b/arch/arm64/include/asm/insn.h @@ -13,31 +13,6 @@ #include #ifndef __ASSEMBLY__ -/* - * ARM Architecture Reference Manual for ARMv8 Profile-A, Issue A.a - * Section C3.1 "A64 instruction index by encoding": - * AArch64 main encoding table - * Bit position - * 28 27 26 25 Encoding Group - * 0 0 - - Unallocated - * 1 0 0 - Data processing, immediate - * 1 0 1 - Branch, exception generation and system instructions - * - 1 - 0 Loads and stores - * - 1 0 1 Data processing - register - * 0 1 1 1 Data processing - SIMD and floating point - * 1 1 1 1 Data processing - SIMD and floating point - * "-" means "don't care" - */ -enum aarch64_insn_encoding_class { - AARCH64_INSN_CLS_UNKNOWN, /* UNALLOCATED */ - AARCH64_INSN_CLS_SVE, /* SVE instructions */ - AARCH64_INSN_CLS_DP_IMM, /* Data processing - immediate */ - AARCH64_INSN_CLS_DP_REG, /* Data processing - register */ - AARCH64_INSN_CLS_DP_FPSIMD, /* Data processing - SIMD and FP */ - AARCH64_INSN_CLS_LDST, /* Loads and stores */ - AARCH64_INSN_CLS_BR_SYS, /* Branch, exception generation and - * system instructions */ -}; enum aarch64_insn_hint_cr_op { AARCH64_INSN_HINT_NOP = 0x0 << 5, @@ -326,6 +301,23 @@ static __always_inline u32 aarch64_insn_get_##abbr##_value(void) \ return (val); \ } +/* + * ARM Architecture Reference Manual for ARMv8 Profile-A, Issue A.a + * Section C3.1 "A64 instruction index by encoding": + * AArch64 main encoding table + * Bit position + * 28 27 26 25 Encoding Group + * 0 0 - - Unallocated + * 1 0 0 - Data processing, immediate + * 1 0 1 - Branch, exception generation and system instructions + * - 1 - 0 Loads and stores + * - 1 0 1 Data processing - register + * 0 1 1 1 Data processing - SIMD and floating point + * 1 1 1 1 Data processing - SIMD and floating point + * "-" means "don't care" + */ +__AARCH64_INSN_FUNCS(class_branch_sys, 0x1c000000, 0x14000000) + __AARCH64_INSN_FUNCS(adr, 0x9F000000, 0x10000000) __AARCH64_INSN_FUNCS(adrp, 0x9F000000, 0x90000000) __AARCH64_INSN_FUNCS(prfm, 0x3FC00000, 0x39800000) diff --git a/arch/arm64/kernel/probes/decode-insn.c b/arch/arm64/kernel/probes/decode-insn.c index 104101f633b10..968d5fffe2330 100644 --- a/arch/arm64/kernel/probes/decode-insn.c +++ b/arch/arm64/kernel/probes/decode-insn.c @@ -24,7 +24,7 @@ static bool __kprobes aarch64_insn_is_steppable(u32 insn) * currently safe. Lastly, MSR instructions can do any number of nasty * things we can't handle during single-stepping. */ - if (aarch64_get_insn_class(insn) == AARCH64_INSN_CLS_BR_SYS) { + if (aarch64_insn_is_class_branch_sys(insn)) { if (aarch64_insn_is_branch(insn) || aarch64_insn_is_msr_imm(insn) || aarch64_insn_is_msr_reg(insn) || diff --git a/arch/arm64/lib/insn.c b/arch/arm64/lib/insn.c index 67c1be804cc3a..99194464d675a 100644 --- a/arch/arm64/lib/insn.c +++ b/arch/arm64/lib/insn.c @@ -20,30 +20,6 @@ #define AARCH64_INSN_N_BIT BIT(22) #define AARCH64_INSN_LSL_12 BIT(22) -static const int aarch64_insn_encoding_class[] = { - AARCH64_INSN_CLS_UNKNOWN, - AARCH64_INSN_CLS_UNKNOWN, - AARCH64_INSN_CLS_SVE, - AARCH64_INSN_CLS_UNKNOWN, - AARCH64_INSN_CLS_LDST, - AARCH64_INSN_CLS_DP_REG, - AARCH64_INSN_CLS_LDST, - AARCH64_INSN_CLS_DP_FPSIMD, - AARCH64_INSN_CLS_DP_IMM, - AARCH64_INSN_CLS_DP_IMM, - AARCH64_INSN_CLS_BR_SYS, - AARCH64_INSN_CLS_BR_SYS, - AARCH64_INSN_CLS_LDST, - AARCH64_INSN_CLS_DP_REG, - AARCH64_INSN_CLS_LDST, - AARCH64_INSN_CLS_DP_FPSIMD, -}; - -enum aarch64_insn_encoding_class __kprobes aarch64_get_insn_class(u32 insn) -{ - return aarch64_insn_encoding_class[(insn >> 25) & 0xf]; -} - static int __kprobes aarch64_get_imm_shift_mask(enum aarch64_insn_imm_type type, u32 *maskp, int *shiftp) {