From d449ceb11b3884770c06e71cf15edc9f3b4c9b05 Mon Sep 17 00:00:00 2001 From: Russell King Date: Wed, 11 Jul 2018 10:31:31 +0100 Subject: [PATCH] ARM: net: bpf: enumerate the JIT scratch stack layout Enumerate the contents of the JIT scratch stack layout used for storing some of the JITs 64-bit registers, tail call counter and AX register. Signed-off-by: Russell King Signed-off-by: Daniel Borkmann --- arch/arm/net/bpf_jit_32.c | 59 +++++++++++++++++++++++++++++++++-------------- 1 file changed, 42 insertions(+), 17 deletions(-) diff --git a/arch/arm/net/bpf_jit_32.c b/arch/arm/net/bpf_jit_32.c index f6a62ae44a65..f2e6ffe57788 100644 --- a/arch/arm/net/bpf_jit_32.c +++ b/arch/arm/net/bpf_jit_32.c @@ -72,7 +72,38 @@ #define CALLEE_PUSH_MASK (CALLEE_MASK | 1 << ARM_LR) #define CALLEE_POP_MASK (CALLEE_MASK | 1 << ARM_PC) -#define STACK_OFFSET(k) (k) +enum { + /* Stack layout - these are offsets from (top of stack - 4) */ + BPF_R2_HI, + BPF_R2_LO, + BPF_R3_HI, + BPF_R3_LO, + BPF_R4_HI, + BPF_R4_LO, + BPF_R5_HI, + BPF_R5_LO, + BPF_R7_HI, + BPF_R7_LO, + BPF_R8_HI, + BPF_R8_LO, + BPF_R9_HI, + BPF_R9_LO, + BPF_FP_HI, + BPF_FP_LO, + BPF_TC_HI, + BPF_TC_LO, + BPF_AX_HI, + BPF_AX_LO, + /* Stack space for BPF_REG_2, BPF_REG_3, BPF_REG_4, + * BPF_REG_5, BPF_REG_7, BPF_REG_8, BPF_REG_9, + * BPF_REG_FP and Tail call counts. + */ + BPF_JIT_SCRATCH_REGS, +}; + +#define STACK_OFFSET(k) ((k) * 4) +#define SCRATCH_SIZE (BPF_JIT_SCRATCH_REGS * 4) + #define TMP_REG_1 (MAX_BPF_JIT_REG + 0) /* TEMP Register 1 */ #define TMP_REG_2 (MAX_BPF_JIT_REG + 1) /* TEMP Register 2 */ #define TCALL_CNT (MAX_BPF_JIT_REG + 2) /* Tail Call Count */ @@ -100,29 +131,29 @@ static const u8 bpf2a32[][2] = { /* arguments from eBPF program to in-kernel function */ [BPF_REG_1] = {ARM_R3, ARM_R2}, /* Stored on stack scratch space */ - [BPF_REG_2] = {STACK_OFFSET(0), STACK_OFFSET(4)}, - [BPF_REG_3] = {STACK_OFFSET(8), STACK_OFFSET(12)}, - [BPF_REG_4] = {STACK_OFFSET(16), STACK_OFFSET(20)}, - [BPF_REG_5] = {STACK_OFFSET(24), STACK_OFFSET(28)}, + [BPF_REG_2] = {STACK_OFFSET(BPF_R2_HI), STACK_OFFSET(BPF_R2_LO)}, + [BPF_REG_3] = {STACK_OFFSET(BPF_R3_HI), STACK_OFFSET(BPF_R3_LO)}, + [BPF_REG_4] = {STACK_OFFSET(BPF_R4_HI), STACK_OFFSET(BPF_R4_LO)}, + [BPF_REG_5] = {STACK_OFFSET(BPF_R5_HI), STACK_OFFSET(BPF_R5_LO)}, /* callee saved registers that in-kernel function will preserve */ [BPF_REG_6] = {ARM_R5, ARM_R4}, /* Stored on stack scratch space */ - [BPF_REG_7] = {STACK_OFFSET(32), STACK_OFFSET(36)}, - [BPF_REG_8] = {STACK_OFFSET(40), STACK_OFFSET(44)}, - [BPF_REG_9] = {STACK_OFFSET(48), STACK_OFFSET(52)}, + [BPF_REG_7] = {STACK_OFFSET(BPF_R7_HI), STACK_OFFSET(BPF_R7_LO)}, + [BPF_REG_8] = {STACK_OFFSET(BPF_R8_HI), STACK_OFFSET(BPF_R8_LO)}, + [BPF_REG_9] = {STACK_OFFSET(BPF_R9_HI), STACK_OFFSET(BPF_R9_LO)}, /* Read only Frame Pointer to access Stack */ - [BPF_REG_FP] = {STACK_OFFSET(56), STACK_OFFSET(60)}, + [BPF_REG_FP] = {STACK_OFFSET(BPF_FP_HI), STACK_OFFSET(BPF_FP_LO)}, /* Temporary Register for internal BPF JIT, can be used * for constant blindings and others. */ [TMP_REG_1] = {ARM_R7, ARM_R6}, [TMP_REG_2] = {ARM_R10, ARM_R8}, /* Tail call count. Stored on stack scratch space. */ - [TCALL_CNT] = {STACK_OFFSET(64), STACK_OFFSET(68)}, + [TCALL_CNT] = {STACK_OFFSET(BPF_TC_HI), STACK_OFFSET(BPF_TC_LO)}, /* temporary register for blinding constants. * Stored on stack scratch space. */ - [BPF_REG_AX] = {STACK_OFFSET(72), STACK_OFFSET(76)}, + [BPF_REG_AX] = {STACK_OFFSET(BPF_AX_HI), STACK_OFFSET(BPF_AX_LO)}, }; #define dst_lo dst[1] @@ -227,12 +258,6 @@ static void jit_fill_hole(void *area, unsigned int size) #define STACK_ALIGNMENT 4 #endif -/* Stack space for BPF_REG_2, BPF_REG_3, BPF_REG_4, - * BPF_REG_5, BPF_REG_7, BPF_REG_8, BPF_REG_9, - * BPF_REG_FP and Tail call counts. - */ -#define SCRATCH_SIZE 80 - /* total stack size used in JITed code */ #define _STACK_SIZE (ctx->prog->aux->stack_depth + SCRATCH_SIZE) #define STACK_SIZE ALIGN(_STACK_SIZE, STACK_ALIGNMENT) -- 2.11.0