linux-kernel - [PATCH v2 3/3] powerpc/module64: Use symbolic instructions names.

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Message-Id: <238e7fa33c16b5d1ad946cde5c063890eaed860a.1556814003.git.christophe.leroy@c-s.fr>
Date:   Thu,  2 May 2019 16:27:31 +0000 (UTC)
From:   Christophe Leroy <christophe.leroy@....fr>
To:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH v2 3/3] powerpc/module64: Use symbolic instructions names.

To increase readability/maintainability, replace hard coded
instructions values by symbolic names.

Signed-off-by: Christophe Leroy <christophe.leroy@....fr>
---
v2: rearranged comments ; fixed warning by adding () in an 'if' around X | Y

 arch/powerpc/kernel/module_64.c | 53 +++++++++++++++++++++++++++--------------
 1 file changed, 35 insertions(+), 18 deletions(-)

diff --git a/arch/powerpc/kernel/module_64.c b/arch/powerpc/kernel/module_64.c
index c2e1b06253b8..516c590c7a1f 100644
--- a/arch/powerpc/kernel/module_64.c
+++ b/arch/powerpc/kernel/module_64.c
@@ -133,20 +133,27 @@ struct ppc64_stub_entry
  * the stub, but it's significantly shorter to put these values at the
  * end of the stub code, and patch the stub address (32-bits relative
  * to the TOC ptr, r2) into the stub.
+ *
+ * addis   r11,r2, <high>
+ * addi    r11,r11, <low>
+ * std     r2,R2_STACK_OFFSET(r1)
+ * ld      r12,32(r11)
+ * ld      r2,40(r11)
+ * mtctr   r12
+ * bctr
  */
-
 static u32 ppc64_stub_insns[] = {
-	0x3d620000,			/* addis   r11,r2, <high> */
-	0x396b0000,			/* addi    r11,r11, <low> */
+	PPC_INST_ADDIS | __PPC_RT(R11) | __PPC_RA(R2),
+	PPC_INST_ADDI | __PPC_RT(R11) | __PPC_RA(R11),
 	/* Save current r2 value in magic place on the stack. */
-	0xf8410000|R2_STACK_OFFSET,	/* std     r2,R2_STACK_OFFSET(r1) */
-	0xe98b0020,			/* ld      r12,32(r11) */
+	PPC_INST_STD | __PPC_RS(R2) | __PPC_RA(R1) | R2_STACK_OFFSET,
+	PPC_INST_LD | __PPC_RT(R12) | __PPC_RA(R11) | 32,
 #ifdef PPC64_ELF_ABI_v1
 	/* Set up new r2 from function descriptor */
-	0xe84b0028,			/* ld      r2,40(r11) */
+	PPC_INST_LD | __PPC_RT(R2) | __PPC_RA(R11) | 40,
 #endif
-	0x7d8903a6,			/* mtctr   r12 */
-	0x4e800420			/* bctr */
+	PPC_INST_MTCTR | __PPC_RS(R12),
+	PPC_INST_BCTR,
 };
 
 #ifdef CONFIG_DYNAMIC_FTRACE
@@ -704,18 +711,21 @@ int apply_relocate_add(Elf64_Shdr *sechdrs,
 		         *	ld r2, ...(r12)
 			 *	add r2, r2, r12
 			 */
-			if ((((uint32_t *)location)[0] & ~0xfffc)
-			    != 0xe84c0000)
+			if ((((uint32_t *)location)[0] & ~0xfffc) !=
+			    PPC_INST_LD | __PPC_RT(R2) | __PPC_RA(R12))
 				break;
-			if (((uint32_t *)location)[1] != 0x7c426214)
+			if (((uint32_t *)location)[1] !=
+			    PPC_INST_ADD | __PPC_RT(R2) | __PPC_RA(R2) | __PPC_RB(R12))
 				break;
 			/*
 			 * If found, replace it with:
 			 *	addis r2, r12, (.TOC.-func)@ha
 			 *	addi r2, r12, (.TOC.-func)@l
 			 */
-			((uint32_t *)location)[0] = 0x3c4c0000 + PPC_HA(value);
-			((uint32_t *)location)[1] = 0x38420000 + PPC_LO(value);
+			((uint32_t *)location)[0] = PPC_INST_ADDIS | __PPC_RT(R2) |
+						    __PPC_RA(R12) | PPC_HA(value);
+			((uint32_t *)location)[1] = PPC_INST_ADDI | __PPC_RT(R2) |
+						    __PPC_RA(R12) | PPC_LO(value);
 			break;
 
 		case R_PPC64_REL16_HA:
@@ -769,12 +779,19 @@ static unsigned long create_ftrace_stub(const Elf64_Shdr *sechdrs,
 {
 	struct ppc64_stub_entry *entry;
 	unsigned int i, num_stubs;
+	/*
+	 * ld      r12,PACATOC(r13)
+	 * addis   r12,r12,<high>
+	 * addi    r12,r12,<low>
+	 * mtctr   r12
+	 * bctr
+	 */
 	static u32 stub_insns[] = {
-		0xe98d0000 | PACATOC, 	/* ld      r12,PACATOC(r13)	*/
-		0x3d8c0000,		/* addis   r12,r12,<high>	*/
-		0x398c0000, 		/* addi    r12,r12,<low>	*/
-		0x7d8903a6, 		/* mtctr   r12			*/
-		0x4e800420, 		/* bctr				*/
+		PPC_INST_LD | __PPC_RT(R12) | __PPC_RA(R13) | PACATOC,
+		PPC_INST_ADDIS | __PPC_RT(R12) | __PPC_RA(R12),
+		PPC_INST_ADDI | __PPC_RT(R12) | __PPC_RA(R12),
+		PPC_INST_MTCTR | __PPC_RS(R12),
+		PPC_INST_BCTR,
 	};
 	long reladdr;
 
-- 
2.13.3