#include "bpf_jit_32.h"
- int bpf_jit_enable __read_mostly;
-
+/*
+ * eBPF prog stack layout:
+ *
+ * high
+ * original ARM_SP => +-----+
+ * | | callee saved registers
+ * +-----+ <= (BPF_FP + SCRATCH_SIZE)
+ * | ... | eBPF JIT scratch space
+ * eBPF fp register => +-----+
+ * (BPF_FP) | ... | eBPF prog stack
+ * +-----+
+ * |RSVD | JIT scratchpad
+ * current ARM_SP => +-----+ <= (BPF_FP - STACK_SIZE + SCRATCH_SIZE)
+ * | |
+ * | ... | Function call stack
+ * | |
+ * +-----+
+ * low
+ *
+ * The callee saved registers depends on whether frame pointers are enabled.
+ * With frame pointers (to be compliant with the ABI):
+ *
+ * high
+ * original ARM_SP => +------------------+ \
+ * | pc | |
+ * current ARM_FP => +------------------+ } callee saved registers
+ * |r4-r8,r10,fp,ip,lr| |
+ * +------------------+ /
+ * low
+ *
+ * Without frame pointers:
+ *
+ * high
+ * original ARM_SP => +------------------+
+ * | r4-r8,r10,fp,lr | callee saved registers
+ * current ARM_FP => +------------------+
+ * low
+ *
+ * When popping registers off the stack at the end of a BPF function, we
+ * reference them via the current ARM_FP register.
+ */
+#define CALLEE_MASK (1 << ARM_R4 | 1 << ARM_R5 | 1 << ARM_R6 | \
+ 1 << ARM_R7 | 1 << ARM_R8 | 1 << ARM_R10 | \
+ 1 << ARM_FP)
+#define CALLEE_PUSH_MASK (CALLEE_MASK | 1 << ARM_LR)
+#define CALLEE_POP_MASK (CALLEE_MASK | 1 << ARM_PC)
+
#define STACK_OFFSET(k) (k)
#define TMP_REG_1 (MAX_BPF_JIT_REG + 0) /* TEMP Register 1 */
#define TMP_REG_2 (MAX_BPF_JIT_REG + 1) /* TEMP Register 2 */