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Commit c2ea1d56 authored by Ralf Baechle's avatar Ralf Baechle
Browse files

MIPS: Avoid potential hazard on Context register 



set_saved_sp reads Context register. Avoid reading stale value from
earlier incomplete write.

Issue found and fixed for head.S by Chris Dearman <chris@mips.com>.

Signed-off-by: default avatarChris Dearman <chris@mips.com>
Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
parent cd847b78

arch/mips/include/asm/mmu_context.h

+3 −0
Original line number Original line Diff line number Diff line
@@ -16,6 +16,7 @@ 
#include <linux/smp.h>

#include <linux/smp.h>

#include <linux/slab.h>

#include <linux/slab.h>

#include <asm/cacheflush.h>

#include <asm/cacheflush.h>

#include <asm/hazards.h>

#include <asm/tlbflush.h>

#include <asm/tlbflush.h>

#ifdef CONFIG_MIPS_MT_SMTC

#ifdef CONFIG_MIPS_MT_SMTC

#include <asm/mipsmtregs.h>

#include <asm/mipsmtregs.h>
@@ -36,11 +37,13 @@ extern unsigned long pgd_current[]; 
#ifdef CONFIG_32BIT

#ifdef CONFIG_32BIT

#define TLBMISS_HANDLER_SETUP()						\

#define TLBMISS_HANDLER_SETUP()						\

	write_c0_context((unsigned long) smp_processor_id() << 25);	\

	write_c0_context((unsigned long) smp_processor_id() << 25);	\

	back_to_back_c0_hazard();					\

	TLBMISS_HANDLER_SETUP_PGD(swapper_pg_dir)

	TLBMISS_HANDLER_SETUP_PGD(swapper_pg_dir)

#endif

#endif

#ifdef CONFIG_64BIT

#ifdef CONFIG_64BIT

#define TLBMISS_HANDLER_SETUP()						\

#define TLBMISS_HANDLER_SETUP()						\

	write_c0_context((unsigned long) smp_processor_id() << 26);	\

	write_c0_context((unsigned long) smp_processor_id() << 26);	\

	back_to_back_c0_hazard();					\

	TLBMISS_HANDLER_SETUP_PGD(swapper_pg_dir)

	TLBMISS_HANDLER_SETUP_PGD(swapper_pg_dir)

#endif

#endif

arch/mips/kernel/head.S

+1 −0
Original line number Original line Diff line number Diff line
@@ -191,6 +191,7 @@ NESTED(kernel_entry, 16, sp) # kernel entry point 
	/* Set the SP after an empty pt_regs.  */

	/* Set the SP after an empty pt_regs.  */

	PTR_LI		sp, _THREAD_SIZE - 32 - PT_SIZE

	PTR_LI		sp, _THREAD_SIZE - 32 - PT_SIZE

	PTR_ADDU	sp, $28

	PTR_ADDU	sp, $28

	back_to_back_c0_hazard

	set_saved_sp	sp, t0, t1

	set_saved_sp	sp, t0, t1

	PTR_SUBU	sp, 4 * SZREG		# init stack pointer

	PTR_SUBU	sp, 4 * SZREG		# init stack pointer