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| author | Ard Biesheuvel <ardb@kernel.org> | 2021-11-25 10:26:44 +0100 |
|---|---|---|
| committer | Ard Biesheuvel <ardb@kernel.org> | 2021-12-06 12:49:17 +0100 |
| commit | 7b9896c352073156a325c3bb0dc4c46e06e2a468 (patch) | |
| tree | a9e6e3be8a6a2b91a147f3e9ae82dfb7fbd860e5 /arch/arm/include/asm/insn.h | |
| parent | ARM: assembler: add optimized ldr/str macros to load variables from memory (diff) | |
| download | linux-7b9896c352073156a325c3bb0dc4c46e06e2a468.tar.xz linux-7b9896c352073156a325c3bb0dc4c46e06e2a468.zip | |
ARM: percpu: add SMP_ON_UP support
Permit the use of the TPIDRPRW system register for carrying the per-CPU
offset in generic SMP configurations that also target non-SMP capable
ARMv6 cores. This uses the SMP_ON_UP code patching framework to turn all
TPIDRPRW accesses into reads/writes of entry #0 in the __per_cpu_offset
array.
While at it, switch over some existing direct TPIDRPRW accesses in asm
code to invocations of a new helper that is patched in the same way when
necessary.
Note that CPU_V6+SMP without SMP_ON_UP results in a kernel that does not
boot on v6 CPUs without SMP extensions, so add this dependency to
Kconfig as well.
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/insn.h')
| -rw-r--r-- | arch/arm/include/asm/insn.h | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/arch/arm/include/asm/insn.h b/arch/arm/include/asm/insn.h index 5475cbf9fb6b..a160ed3ea427 100644 --- a/arch/arm/include/asm/insn.h +++ b/arch/arm/include/asm/insn.h @@ -2,6 +2,30 @@ #ifndef __ASM_ARM_INSN_H #define __ASM_ARM_INSN_H +#include <linux/types.h> + +/* + * Avoid a literal load by emitting a sequence of ADD/LDR instructions with the + * appropriate relocations. The combined sequence has a range of -/+ 256 MiB, + * which should be sufficient for the core kernel as well as modules loaded + * into the module region. (Not supported by LLD before release 14) + */ +#if !(defined(MODULE) && defined(CONFIG_ARM_MODULE_PLTS)) && \ + !(defined(CONFIG_LD_IS_LLD) && CONFIG_LLD_VERSION < 140000) +#define LOAD_SYM_ARMV6(reg, sym) \ + " .globl " #sym " \n\t" \ + " .reloc 10f, R_ARM_ALU_PC_G0_NC, " #sym " \n\t" \ + " .reloc 11f, R_ARM_ALU_PC_G1_NC, " #sym " \n\t" \ + " .reloc 12f, R_ARM_LDR_PC_G2, " #sym " \n\t" \ + "10: sub " #reg ", pc, #8 \n\t" \ + "11: sub " #reg ", " #reg ", #4 \n\t" \ + "12: ldr " #reg ", [" #reg ", #0] \n\t" +#else +#define LOAD_SYM_ARMV6(reg, sym) \ + " ldr " #reg ", =" #sym " \n\t" \ + " ldr " #reg ", [" #reg "] \n\t" +#endif + static inline unsigned long arm_gen_nop(void) { |