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Commit e9ab7a2e authored by Julien Thierry's avatar Julien Thierry Committed by Catalin Marinas
Browse files

arm64: alternative: Allow alternative status checking per cpufeature 



In preparation for the application of alternatives at different points
during the boot process, provide the possibility to check whether
alternatives for a feature of interest was already applied instead of
having a global boolean for all alternatives.

Make VHE enablement code check for the VHE feature instead of considering
all alternatives.

Signed-off-by: default avatarJulien Thierry <julien.thierry@arm.com>
Acked-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Marc Zyngier <Marc.Zyngier@arm.com>
Cc: Christoffer Dall <Christoffer.Dall@arm.com>
Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent 8cb7eff3

arch/arm64/include/asm/alternative.h

+1 −2
Original line number Diff line number Diff line
@@ -14,8 +14,6 @@ 
#include <linux/stddef.h>

#include <linux/stringify.h>



extern int alternatives_applied;



struct alt_instr {

	s32 orig_offset;	/* offset to original instruction */

	s32 alt_offset;		/* offset to replacement instruction */
@@ -28,6 +26,7 @@ typedef void (*alternative_cb_t)(struct alt_instr *alt, 
				 __le32 *origptr, __le32 *updptr, int nr_inst);



void __init apply_alternatives_all(void);

bool alternative_is_applied(u16 cpufeature);



#ifdef CONFIG_MODULES

void apply_alternatives_module(void *start, size_t length);

arch/arm64/kernel/alternative.c

+17 −4
Original line number Diff line number Diff line
@@ -32,13 +32,23 @@ 
#define ALT_ORIG_PTR(a)		__ALT_PTR(a, orig_offset)

#define ALT_REPL_PTR(a)		__ALT_PTR(a, alt_offset)



int alternatives_applied;

static int all_alternatives_applied;



static DECLARE_BITMAP(applied_alternatives, ARM64_NCAPS);



struct alt_region {

	struct alt_instr *begin;

	struct alt_instr *end;

};



bool alternative_is_applied(u16 cpufeature)

{

	if (WARN_ON(cpufeature >= ARM64_NCAPS))

		return false;



	return test_bit(cpufeature, applied_alternatives);

}



/*

 * Check if the target PC is within an alternative block.

 */
@@ -192,6 +202,9 @@ static void __apply_alternatives(void *alt_region, bool is_module) 
		dsb(ish);

		__flush_icache_all();

		isb();



		/* We applied all that was available */

		bitmap_copy(applied_alternatives, cpu_hwcaps, ARM64_NCAPS);

	}

}
@@ -208,14 +221,14 @@ static int __apply_alternatives_multi_stop(void *unused) 


	/* We always have a CPU 0 at this point (__init) */

	if (smp_processor_id()) {

		while (!READ_ONCE(alternatives_applied))

		while (!READ_ONCE(all_alternatives_applied))

			cpu_relax();

		isb();

	} else {

		BUG_ON(alternatives_applied);

		BUG_ON(all_alternatives_applied);

		__apply_alternatives(&region, false);

		/* Barriers provided by the cache flushing */

		WRITE_ONCE(alternatives_applied, 1);

		WRITE_ONCE(all_alternatives_applied, 1);

	}



	return 0;

arch/arm64/kernel/cpufeature.c

+1 −1
Original line number Diff line number Diff line
@@ -1118,7 +1118,7 @@ static void cpu_copy_el2regs(const struct arm64_cpu_capabilities *__unused) 
	 * that, freshly-onlined CPUs will set tpidr_el2, so we don't need to

	 * do anything here.

	 */

	if (!alternatives_applied)

	if (!alternative_is_applied(ARM64_HAS_VIRT_HOST_EXTN))

		write_sysreg(read_sysreg(tpidr_el1), tpidr_el2);

}

#endif