Commit 70ec3a6c authored by Russell King's avatar Russell King
Browse files

ARM: net: bpf: move stack documentation 



Move the stack documentation towards the top of the file, where it's
relevant for things like the register layout.

Signed-off-by: default avatarRussell King <rmk+kernel@armlinux.org.uk>
parent d1220efd

arch/arm/net/bpf_jit_32.c

+21 −21
Original line number Diff line number Diff line
@@ -27,6 +27,27 @@ 


int bpf_jit_enable __read_mostly;



/*

 * eBPF prog stack layout

 *

 *                         high

 * original ARM_SP =>     +-----+ eBPF prologue

 *                        |FP/LR|

 * current ARM_FP =>      +-----+

 *                        | ... | callee saved registers

 * eBPF fp register =>    +-----+ <= (BPF_FP)

 *                        | ... | eBPF JIT scratch space

 *                        |     | eBPF prog stack

 *                        +-----+

 *                        |RSVD | JIT scratchpad

 * current ARM_SP =>      +-----+ <= (BPF_FP - STACK_SIZE)

 *                        |     |

 *                        | ... | Function call stack

 *                        |     |

 *                        +-----+

 *                          low

 */



#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 */
@@ -1091,27 +1112,6 @@ static void build_prologue(struct jit_ctx *ctx) 


	u16 reg_set = 0;



	/*

	 * eBPF prog stack layout

	 *

	 *                         high

	 * original ARM_SP =>     +-----+ eBPF prologue

	 *                        |FP/LR|

	 * current ARM_FP =>      +-----+

	 *                        | ... | callee saved registers

	 * eBPF fp register =>    +-----+ <= (BPF_FP)

	 *                        | ... | eBPF JIT scratch space

	 *                        |     | eBPF prog stack

	 *                        +-----+

	 *			  |RSVD | JIT scratchpad

	 * current A64_SP =>      +-----+ <= (BPF_FP - STACK_SIZE)

	 *                        |     |

	 *                        | ... | Function call stack

	 *                        |     |

	 *                        +-----+

	 *                          low

	 */



	/* Save callee saved registers. */

	reg_set |= (1<<r4) | (1<<r5) | (1<<r6) | (1<<r7) | (1<<r8) | (1<<r10);

#ifdef CONFIG_FRAME_POINTER