linux-kernel - [PATCH 4.14 17/71] ARM: net: bpf: move stack documentation

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Date:   Mon, 29 Jan 2018 13:56:45 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Russell King <rmk+kernel@...linux.org.uk>
Subject: [PATCH 4.14 17/71] ARM: net: bpf: move stack documentation

4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Russell King <rmk+kernel@...linux.org.uk>

commit 70ec3a6c2c11e4b0e107a65de943a082f9aff351 upstream.

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

Signed-off-by: Russell King <rmk+kernel@...linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/arm/net/bpf_jit_32.c |   42 +++++++++++++++++++++---------------------
 1 file changed, 21 insertions(+), 21 deletions(-)

--- a/arch/arm/net/bpf_jit_32.c
+++ b/arch/arm/net/bpf_jit_32.c
@@ -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_ct
 
 	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