linux-kernel - [PATCH v2 1/8] powerpc: Create a helper for getting the kernel toc value

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Message-Id: <1456737989-8755-1-git-send-email-mpe@ellerman.id.au>
Date:	Mon, 29 Feb 2016 20:26:22 +1100
From:	Michael Ellerman <mpe@...erman.id.au>
To:	<linuxppc-dev@...abs.org>
Cc:	bsingharora@...il.com, duwe@....de, <linux-kernel@...r.kernel.org>,
	rostedt@...dmis.org, kamalesh@...ux.vnet.ibm.com, pmladek@...e.com,
	jeyu@...hat.com, jkosina@...e.cz, live-patching@...r.kernel.org,
	mbenes@...e.cz
Subject: [PATCH v2 1/8] powerpc: Create a helper for getting the kernel toc value

Move the logic to work out the kernel toc pointer into a header. This is
a good cleanup, and also means we can use it elsewhere in future.

Signed-off-by: Michael Ellerman <mpe@...erman.id.au>
---
 arch/powerpc/include/asm/sections.h | 12 ++++++++++++
 arch/powerpc/kernel/paca.c          | 11 +----------
 2 files changed, 13 insertions(+), 10 deletions(-)

v2: New.

diff --git a/arch/powerpc/include/asm/sections.h b/arch/powerpc/include/asm/sections.h
index a5e930aca804..abf5866e08c6 100644
--- a/arch/powerpc/include/asm/sections.h
+++ b/arch/powerpc/include/asm/sections.h
@@ -22,6 +22,18 @@ static inline int in_kernel_text(unsigned long addr)
 	return 0;
 }
 
+static inline unsigned long kernel_toc_addr(void)
+{
+	/* Defined by the linker, see vmlinux.lds.S */
+	extern unsigned long __toc_start;
+
+	/*
+	 * The TOC register (r2) points 32kB into the TOC, so that 64kB of
+	 * the TOC can be addressed using a single machine instruction.
+	 */
+	return (unsigned long)(&__toc_start) + 0x8000UL;
+}
+
 static inline int overlaps_interrupt_vector_text(unsigned long start,
 							unsigned long end)
 {
diff --git a/arch/powerpc/kernel/paca.c b/arch/powerpc/kernel/paca.c
index 01ea0edf0579..93dae296b6be 100644
--- a/arch/powerpc/kernel/paca.c
+++ b/arch/powerpc/kernel/paca.c
@@ -17,10 +17,6 @@
 #include <asm/pgtable.h>
 #include <asm/kexec.h>
 
-/* This symbol is provided by the linker - let it fill in the paca
- * field correctly */
-extern unsigned long __toc_start;
-
 #ifdef CONFIG_PPC_BOOK3S
 
 /*
@@ -149,11 +145,6 @@ EXPORT_SYMBOL(paca);
 
 void __init initialise_paca(struct paca_struct *new_paca, int cpu)
 {
-       /* The TOC register (GPR2) points 32kB into the TOC, so that 64kB
-	* of the TOC can be addressed using a single machine instruction.
-	*/
-	unsigned long kernel_toc = (unsigned long)(&__toc_start) + 0x8000UL;
-
 #ifdef CONFIG_PPC_BOOK3S
 	new_paca->lppaca_ptr = new_lppaca(cpu);
 #else
@@ -161,7 +152,7 @@ void __init initialise_paca(struct paca_struct *new_paca, int cpu)
 #endif
 	new_paca->lock_token = 0x8000;
 	new_paca->paca_index = cpu;
-	new_paca->kernel_toc = kernel_toc;
+	new_paca->kernel_toc = kernel_toc_addr();
 	new_paca->kernelbase = (unsigned long) _stext;
 	/* Only set MSR:IR/DR when MMU is initialized */
 	new_paca->kernel_msr = MSR_KERNEL & ~(MSR_IR | MSR_DR);
-- 
2.5.0