diff options
Diffstat (limited to 'arch/arm/include/asm/tls.h')
| -rw-r--r-- | arch/arm/include/asm/tls.h | 128 |
1 files changed, 128 insertions, 0 deletions
diff --git a/arch/arm/include/asm/tls.h b/arch/arm/include/asm/tls.h new file mode 100644 index 000000000..5a66c3b13 --- /dev/null +++ b/arch/arm/include/asm/tls.h @@ -0,0 +1,128 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef __ASMARM_TLS_H +#define __ASMARM_TLS_H + +#include <linux/compiler.h> +#include <asm/thread_info.h> + +#ifdef __ASSEMBLY__ +#include <asm/asm-offsets.h> + .macro switch_tls_none, base, tp, tpuser, tmp1, tmp2 + .endm + + .macro switch_tls_v6k, base, tp, tpuser, tmp1, tmp2 + mrc p15, 0, \tmp2, c13, c0, 2 @ get the user r/w register + mcr p15, 0, \tp, c13, c0, 3 @ set TLS register + mcr p15, 0, \tpuser, c13, c0, 2 @ and the user r/w register + str \tmp2, [\base, #TI_TP_VALUE + 4] @ save it + .endm + + .macro switch_tls_v6, base, tp, tpuser, tmp1, tmp2 + ldr \tmp1, =elf_hwcap + ldr \tmp1, [\tmp1, #0] + mov \tmp2, #0xffff0fff + tst \tmp1, #HWCAP_TLS @ hardware TLS available? + streq \tp, [\tmp2, #-15] @ set TLS value at 0xffff0ff0 + mrcne p15, 0, \tmp2, c13, c0, 2 @ get the user r/w register + mcrne p15, 0, \tp, c13, c0, 3 @ yes, set TLS register + mcrne p15, 0, \tpuser, c13, c0, 2 @ set user r/w register + strne \tmp2, [\base, #TI_TP_VALUE + 4] @ save it + .endm + + .macro switch_tls_software, base, tp, tpuser, 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 switch_tls switch_tls_none +#elif defined(CONFIG_CPU_V6) +#define tls_emu 0 +#define has_tls_reg (elf_hwcap & HWCAP_TLS) +#define switch_tls switch_tls_v6 +#elif defined(CONFIG_CPU_32v6K) +#define tls_emu 0 +#define has_tls_reg 1 +#define switch_tls switch_tls_v6k +#else +#define tls_emu 0 +#define has_tls_reg 0 +#define switch_tls switch_tls_software +#endif + +#ifndef __ASSEMBLY__ + +static inline void set_tls(unsigned long val) +{ + struct thread_info *thread; + + thread = current_thread_info(); + + thread->tp_value[0] = val; + + /* + * This code runs with preemption enabled and therefore must + * be reentrant with respect to switch_tls. + * + * We need to ensure ordering between the shadow state and the + * hardware state, so that we don't corrupt the hardware state + * with a stale shadow state during context switch. + * + * If we're preempted here, switch_tls will load TPIDRURO from + * thread_info upon resuming execution and the following mcr + * is merely redundant. + */ + barrier(); + + if (!tls_emu) { + if (has_tls_reg) { + asm("mcr p15, 0, %0, c13, c0, 3" + : : "r" (val)); + } else { +#ifdef CONFIG_KUSER_HELPERS + /* + * 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) = val; +#endif + } + + } +} + +static inline unsigned long get_tpuser(void) +{ + unsigned long reg = 0; + + if (has_tls_reg && !tls_emu) + __asm__("mrc p15, 0, %0, c13, c0, 2" : "=r" (reg)); + + return reg; +} + +static inline void set_tpuser(unsigned long val) +{ + /* Since TPIDRURW is fully context-switched (unlike TPIDRURO), + * we need not update thread_info. + */ + if (has_tls_reg && !tls_emu) { + asm("mcr p15, 0, %0, c13, c0, 2" + : : "r" (val)); + } +} + +static inline void flush_tls(void) +{ + set_tls(0); + set_tpuser(0); +} + +#endif +#endif /* __ASMARM_TLS_H */ |