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authorArd Biesheuvel <ardb@kernel.org>2021-11-25 23:21:45 +0100
committerArd Biesheuvel <ardb@kernel.org>2021-12-06 12:49:17 +0100
commitc2755910373bb5dfb9aa68ba2924036686815c9e (patch)
treeb54e4da6d120da7e911016e4e8d1560ca6dd2d22 /arch/arm/include/asm/tls.h
parentb87cf9118e03d8a83039c88fa348165148f5d487 (diff)
ARM: smp: defer TPIDRURO update for SMP v6 configurations too
Defer TPIDURO updates for user space until exit also for CPU_V6+SMP configurations so that we can decide at runtime whether to use it to carry the current pointer, provided that we are running on a CPU that actually implements this register. This is needed for THREAD_INFO_IN_TASK support for UP systems, which requires that all SMP capable systems use the TPIDRURO based access to 'current' as the only remaining alternative will be a global variable which only works on UP. Acked-by: Linus Walleij <linus.walleij@linaro.org> Acked-by: Nicolas Pitre <nico@fluxnic.net> Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Tested-by: Marc Zyngier <maz@kernel.org> Tested-by: Vladimir Murzin <vladimir.murzin@arm.com> # ARMv7M
Diffstat (limited to 'arch/arm/include/asm/tls.h')
-rw-r--r--arch/arm/include/asm/tls.h13
1 files changed, 7 insertions, 6 deletions
diff --git a/arch/arm/include/asm/tls.h b/arch/arm/include/asm/tls.h
index c3296499176c..d712c170c095 100644
--- a/arch/arm/include/asm/tls.h
+++ b/arch/arm/include/asm/tls.h
@@ -18,13 +18,14 @@
.endm
.macro switch_tls_v6, base, tp, tpuser, tmp1, tmp2
- ldr \tmp1, =elf_hwcap
- ldr \tmp1, [\tmp1, #0]
+ ldr_va \tmp1, elf_hwcap
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
+#ifndef CONFIG_SMP
mcrne p15, 0, \tp, c13, c0, 3 @ yes, set TLS register
+#endif
mcrne p15, 0, \tpuser, c13, c0, 2 @ set user r/w register
strne \tmp2, [\base, #TI_TP_VALUE + 4] @ save it
.endm
@@ -43,7 +44,7 @@
#elif defined(CONFIG_CPU_V6)
#define tls_emu 0
#define has_tls_reg (elf_hwcap & HWCAP_TLS)
-#define defer_tls_reg_update 0
+#define defer_tls_reg_update IS_ENABLED(CONFIG_SMP)
#define switch_tls switch_tls_v6
#elif defined(CONFIG_CPU_32v6K)
#define tls_emu 0
@@ -81,11 +82,11 @@ static inline void set_tls(unsigned long val)
*/
barrier();
- if (!tls_emu && !defer_tls_reg_update) {
- if (has_tls_reg) {
+ if (!tls_emu) {
+ if (has_tls_reg && !defer_tls_reg_update) {
asm("mcr p15, 0, %0, c13, c0, 3"
: : "r" (val));
- } else {
+ } else if (!has_tls_reg) {
#ifdef CONFIG_KUSER_HELPERS
/*
* User space must never try to access this