Commit f159f4ed authored by Tony Lindgren's avatar Tony Lindgren Committed by Russell King
Browse files

ARM: 6207/1: Replace CONFIG_HAS_TLS_REG with HWCAP_TLS and check for it on V6 



The TLS register is only available on ARM1136 r1p0 and later.
Set HWCAP_TLS flags if hardware TLS is available and test for
it if CONFIG_CPU_32v6K is not set for V6.

Note that we set the TLS instruction in __kuser_get_tls
dynamically as suggested by Jamie Lokier <jamie@shareable.org>.

Also the __switch_to code is optimized out in most cases as
suggested by Nicolas Pitre <nico@fluxnic.net>.

Reviewed-by: default avatarNicolas Pitre <nicolas.pitre@linaro.org>
Signed-off-by: default avatarTony Lindgren <tony@atomide.com>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent c1b2d970

arch/arm/include/asm/hwcap.h

+1 −0
Original line number Diff line number Diff line
@@ -19,6 +19,7 @@ 
#define HWCAP_NEON	4096

#define HWCAP_VFPv3	8192

#define HWCAP_VFPv3D16	16384

#define HWCAP_TLS	32768



#if defined(__KERNEL__) && !defined(__ASSEMBLY__)

/*

arch/arm/include/asm/tls.h

0 → 100644
+46 −0
Original line number Diff line number Diff line 
#ifndef __ASMARM_TLS_H

#define __ASMARM_TLS_H



#ifdef __ASSEMBLY__

	.macro set_tls_none, tp, tmp1, tmp2

	.endm



	.macro set_tls_v6k, tp, tmp1, tmp2

	mcr	p15, 0, \tp, c13, c0, 3		@ set TLS register

	.endm



	.macro set_tls_v6, tp, tmp1, tmp2

	ldr	\tmp1, =elf_hwcap

	ldr	\tmp1, [\tmp1, #0]

	mov	\tmp2, #0xffff0fff

	tst	\tmp1, #HWCAP_TLS		@ hardware TLS available?

	mcrne	p15, 0, \tp, c13, c0, 3		@ yes, set TLS register

	streq	\tp, [\tmp2, #-15]		@ set TLS value at 0xffff0ff0

	.endm



	.macro set_tls_software, tp, tmp1, tmp2

	mov	\tmp1, #0xffff0fff

	str	\tp, [\tmp1, #-15]		@ set TLS value at 0xffff0ff0

	.endm

#endif



#ifdef CONFIG_TLS_REG_EMUL

#define tls_emu		1

#define has_tls_reg		1

#define set_tls		set_tls_none

#elif __LINUX_ARM_ARCH__ >= 7 ||					\

	(__LINUX_ARM_ARCH__ == 6 && defined(CONFIG_CPU_32v6K))

#define tls_emu		0

#define has_tls_reg		1

#define set_tls		set_tls_v6k

#elif __LINUX_ARM_ARCH__ == 6

#define tls_emu		0

#define has_tls_reg		(elf_hwcap & HWCAP_TLS)

#define set_tls		set_tls_v6

#else

#define tls_emu		0

#define has_tls_reg		0

#define set_tls		set_tls_software

#endif



#endif	/* __ASMARM_TLS_H */

arch/arm/kernel/entry-armv.S

+7 −16
Original line number Diff line number Diff line
@@ -22,6 +22,7 @@ 
#include <asm/thread_notify.h>

#include <asm/unwind.h>

#include <asm/unistd.h>

#include <asm/tls.h>



#include "entry-header.S"
@@ -739,12 +740,7 @@ ENTRY(__switch_to) 
#ifdef CONFIG_MMU

	ldr	r6, [r2, #TI_CPU_DOMAIN]

#endif

#if defined(CONFIG_HAS_TLS_REG)

	mcr	p15, 0, r3, c13, c0, 3		@ set TLS register

#elif !defined(CONFIG_TLS_REG_EMUL)

	mov	r4, #0xffff0fff

	str	r3, [r4, #-15]			@ TLS val at 0xffff0ff0

#endif

	set_tls	r3, r4, r5

#ifdef CONFIG_MMU

	mcr	p15, 0, r6, c3, c0, 0		@ Set domain register

#endif
@@ -1009,17 +1005,12 @@ kuser_cmpxchg_fixup: 
 */



__kuser_get_tls:				@ 0xffff0fe0



#if !defined(CONFIG_HAS_TLS_REG) && !defined(CONFIG_TLS_REG_EMUL)

	ldr	r0, [pc, #(16 - 8)]		@ TLS stored at 0xffff0ff0

#else

	mrc	p15, 0, r0, c13, c0, 3		@ read TLS register

#endif

	ldr	r0, [pc, #(16 - 8)]	@ read TLS, set in kuser_get_tls_init

	usr_ret	lr



	.rep	5

	.word	0			@ pad up to __kuser_helper_version

	.endr

	mrc	p15, 0, r0, c13, c0, 3	@ 0xffff0fe8 hardware TLS code

	.rep	4

	.word	0			@ 0xffff0ff0 software TLS value, then

	.endr				@ pad up to __kuser_helper_version



/*

 * Reference declaration:

arch/arm/kernel/setup.c

+17 −0
Original line number Diff line number Diff line
@@ -269,6 +269,21 @@ static void __init cacheid_init(void) 
extern struct proc_info_list *lookup_processor_type(unsigned int);

extern struct machine_desc *lookup_machine_type(unsigned int);



static void __init feat_v6_fixup(void)

{

	int id = read_cpuid_id();



	if ((id & 0xff0f0000) != 0x41070000)

		return;



	/*

	 * HWCAP_TLS is available only on 1136 r1p0 and later,

	 * see also kuser_get_tls_init.

	 */

	if ((((id >> 4) & 0xfff) == 0xb36) && (((id >> 20) & 3) == 0))

		elf_hwcap &= ~HWCAP_TLS;

}



static void __init setup_processor(void)

{

	struct proc_info_list *list;
@@ -311,6 +326,8 @@ static void __init setup_processor(void) 
	elf_hwcap &= ~HWCAP_THUMB;

#endif



	feat_v6_fixup();



	cacheid_init();

	cpu_proc_init();

}

arch/arm/kernel/traps.c

+30 −11
Original line number Diff line number Diff line
@@ -30,6 +30,7 @@ 
#include <asm/unistd.h>

#include <asm/traps.h>

#include <asm/unwind.h>

#include <asm/tls.h>



#include "ptrace.h"

#include "signal.h"
@@ -518,9 +519,12 @@ asmlinkage int arm_syscall(int no, struct pt_regs *regs) 


	case NR(set_tls):

		thread->tp_value = regs->ARM_r0;

#if defined(CONFIG_HAS_TLS_REG)

		asm ("mcr p15, 0, %0, c13, c0, 3" : : "r" (regs->ARM_r0) );

#elif !defined(CONFIG_TLS_REG_EMUL)

		if (tls_emu)

			return 0;

		if (has_tls_reg) {

			asm ("mcr p15, 0, %0, c13, c0, 3"

				: : "r" (regs->ARM_r0));

		} else {

			/*

			 * User space must never try to access this directly.

			 * Expect your app to break eventually if you do so.
@@ -528,7 +532,7 @@ asmlinkage int arm_syscall(int no, struct pt_regs *regs) 
			 * (see entry-armv.S for details)

			 */

			*((unsigned int *)0xffff0ff0) = regs->ARM_r0;

#endif

		}

		return 0;



#ifdef CONFIG_NEEDS_SYSCALL_FOR_CMPXCHG
@@ -743,6 +747,16 @@ void __init trap_init(void) 
	return;

}



static void __init kuser_get_tls_init(unsigned long vectors)

{

	/*

	 * vectors + 0xfe0 = __kuser_get_tls

	 * vectors + 0xfe8 = hardware TLS instruction at 0xffff0fe8

	 */

	if (tls_emu || has_tls_reg)

		memcpy((void *)vectors + 0xfe0, (void *)vectors + 0xfe8, 4);

}



void __init early_trap_init(void)

{

	unsigned long vectors = CONFIG_VECTORS_BASE;
@@ -760,6 +774,11 @@ void __init early_trap_init(void) 
	memcpy((void *)vectors + 0x200, __stubs_start, __stubs_end - __stubs_start);

	memcpy((void *)vectors + 0x1000 - kuser_sz, __kuser_helper_start, kuser_sz);



	/*

	 * Do processor specific fixups for the kuser helpers

	 */

	kuser_get_tls_init(vectors);



	/*

	 * Copy signal return handlers into the vector page, and

	 * set sigreturn to be a pointer to these.

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