From 384ba7563aaede68c38be361b9b5edd8bf4b3d0e Mon Sep 17 00:00:00 2001 From: Joel Sherrill Date: Thu, 6 Oct 2005 19:36:41 +0000 Subject: 2005-10-06 Till Straumann PR 833/bsps * irq/irq_asm.S: Currently, all (new exception) BSPs explicitely enable the FPU across the user ISR but DONT save/restore the FPU context. Any use of the FPU fron the user handler (e.g., due to GCC optimizations) result in corruption. The fix results in an exception in such cases (user ISR must explicitely save/enable/restore FPU). --- c/src/lib/libbsp/powerpc/mpc8260ads/irq/irq_asm.S | 28 +++++++++++++++++++---- 1 file changed, 24 insertions(+), 4 deletions(-) (limited to 'c/src/lib/libbsp/powerpc/mpc8260ads/irq/irq_asm.S') diff --git a/c/src/lib/libbsp/powerpc/mpc8260ads/irq/irq_asm.S b/c/src/lib/libbsp/powerpc/mpc8260ads/irq/irq_asm.S index a8971f5b1d..a0aa73abc0 100644 --- a/c/src/lib/libbsp/powerpc/mpc8260ads/irq/irq_asm.S +++ b/c/src/lib/libbsp/powerpc/mpc8260ads/irq/irq_asm.S @@ -12,6 +12,9 @@ * Modifications to store nesting level in global _ISR_Nest_level * variable instead of SPRG0. Andy Dachs * + * Till Straumann , 2005/4: + * - DONT enable FP across user ISR since fpregs are never saved!! + * * $Id$ */ @@ -92,11 +95,7 @@ SYM (shared_raw_irq_code_entry): * also, on CPUs with FP, enable FP so that FP context can be * saved and restored (using FP instructions) */ -#if (PPC_HAS_FPU == 0) ori r3, r3, MSR_RI /*| MSR_IR | MSR_DR*/ -#else - ori r3, r3, MSR_RI | /*MSR_IR | MSR_DR |*/ MSR_FP -#endif mtmsr r3 SYNC @@ -297,6 +296,27 @@ nested: rfi switch: +#if ( PPC_HAS_FPU != 0 ) +#if ! defined( CPU_USE_DEFERRED_FP_SWITCH ) +#error missing include file??? +#endif + mfmsr r4 +#if ( CPU_USE_DEFERRED_FP_SWITCH == TRUE ) + /* if the executing thread has FP enabled propagate + * this now so _Thread_Dispatch can save/restore the FPREGS + * NOTE: it is *crucial* to disable the FPU across the + * user ISR [independent of using the 'deferred' + * strategy or not]. We don't save FP regs across + * the user ISR and hence we prefer an exception to + * be raised rather than experiencing corruption. + */ + lwz r3, SRR1_FRAME_OFFSET(r1) + rlwimi r4, r3, 0, 18, 18 /* MSR_FP */ +#else + ori r4, r4, MSR_FP +#endif + mtmsr r4 +#endif bl SYM (_Thread_Dispatch) easy_exit: -- cgit v1.2.3