The following commit has been merged in the linux branch: commit c2ea1d56eaf084c66177eb5658ff4065e79b36ea Author: Ralf Baechle ralf@linux-mips.org Date: Tue Oct 13 23:23:28 2009 +0200

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: Chris Dearman chris@mips.com Signed-off-by: Ralf Baechle ralf@linux-mips.org

diff --git a/arch/mips/include/asm/mmu_context.h b/arch/mips/include/asm/mmu_context.h index ed331c2..6083db5 100644 --- a/arch/mips/include/asm/mmu_context.h +++ b/arch/mips/include/asm/mmu_context.h @@ -16,6 +16,7 @@ #include <linux/smp.h> #include <linux/slab.h> #include <asm/cacheflush.h> +#include <asm/hazards.h> #include <asm/tlbflush.h> #ifdef CONFIG_MIPS_MT_SMTC #include <asm/mipsmtregs.h> @@ -36,11 +37,13 @@ extern unsigned long pgd_current[]; #ifdef CONFIG_32BIT #define TLBMISS_HANDLER_SETUP() \ write_c0_context((unsigned long) smp_processor_id() << 25); \ + back_to_back_c0_hazard(); \ TLBMISS_HANDLER_SETUP_PGD(swapper_pg_dir) #endif #ifdef CONFIG_64BIT #define TLBMISS_HANDLER_SETUP() \ write_c0_context((unsigned long) smp_processor_id() << 26); \ + back_to_back_c0_hazard(); \ TLBMISS_HANDLER_SETUP_PGD(swapper_pg_dir) #endif

diff --git a/arch/mips/kernel/head.S b/arch/mips/kernel/head.S index 531ce7b..ea695d9 100644 --- a/arch/mips/kernel/head.S +++ b/arch/mips/kernel/head.S @@ -191,6 +191,7 @@ NESTED(kernel_entry, 16, sp) # kernel entry point /* Set the SP after an empty pt_regs. */ PTR_LI sp, _THREAD_SIZE - 32 - PT_SIZE PTR_ADDU sp, $28 + back_to_back_c0_hazard set_saved_sp sp, t0, t1 PTR_SUBU sp, 4 * SZREG # init stack pointer