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

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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: Nicolas Pitre <nicolas.pitre@linaro.org>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Tony Lindgren
2010-07-05 14:53:10 +01:00
committed by Russell King
parent c1b2d9704c
commit f159f4ed55
8 changed files with 105 additions and 41 deletions
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41
arch/arm/kernel/traps.c
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@ -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"
@ -518,17 +519,20 @@ 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)
/*
* User space must never try to access this directly.
* Expect your app to break eventually if you do so.
* The user helper at 0xffff0fe0 must be used instead.
* (see entry-armv.S for details)
*/
*((unsigned int *)0xffff0ff0) = regs->ARM_r0;
#endif
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.
* The user helper at 0xffff0fe0 must be used instead.
* (see entry-armv.S for details)
*/
*((unsigned int *)0xffff0ff0) = regs->ARM_r0;
}
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.