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FP context switch may be called from environment with no

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FPU available (ISR, int-only task) - switch FPU on
 for the switch and restore MSR_FP after it's done.
This commit is contained in:
Till Straumann
2006-06-19 19:59:59 +00:00
parent bbc87852db
commit 368894feef
2 changed files with 35 additions and 2 deletions
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8
c/src/lib/libcpu/powerpc/ChangeLog
View File

@@ -1,7 +1,11 @@
2006-06-19 Till Straumann <strauman@slac.stanford.edu> 2006-06-19 Till Straumann <strauman@slac.stanford.edu>
* new-exceptions/cpu.c: Never allow the FPU to be switched * new-exceptions/cpu.c, new-exceptions/cpu_asm.S: Never
on for integer-only tasks (new gcc may use FP regs implicitely). allow the FPU to be switched on for integer-only tasks
(new gcc may use FP regs implicitely).
FP context switch may be called from environment with no
FPU available (ISR, int-only task) - switch FPU on
for the switch and restore MSR_FP after it's done.
2006-05-16 Ralf Corsepius <ralf.corsepius@rtems.org> 2006-05-16 Ralf Corsepius <ralf.corsepius@rtems.org>

29
c/src/lib/libcpu/powerpc/new-exceptions/cpu_asm.S
View File

@@ -33,6 +33,7 @@
#include <rtems/asm.h> #include <rtems/asm.h>
#include <rtems/powerpc/powerpc.h> #include <rtems/powerpc/powerpc.h>
#include <rtems/powerpc/registers.h>
/* /*
* Offsets for various Contexts * Offsets for various Contexts
@@ -161,6 +162,16 @@
PUBLIC_PROC (_CPU_Context_save_fp) PUBLIC_PROC (_CPU_Context_save_fp)
PROC (_CPU_Context_save_fp): PROC (_CPU_Context_save_fp):
#if (PPC_HAS_FPU == 1) #if (PPC_HAS_FPU == 1)
/* A FP context switch may occur in an ISR or exception handler when the FPU is not
* available. Therefore, we must explicitely enable it here!
*/
mfmsr r4
andi. r5,r4,MSR_FP
bne 1f
ori r5,r4,MSR_FP
mtmsr r5
isync
1:
lwz r3, 0(r3) lwz r3, 0(r3)
STF f0, FP_0(r3) STF f0, FP_0(r3)
STF f1, FP_1(r3) STF f1, FP_1(r3)
@@ -196,6 +207,10 @@ PROC (_CPU_Context_save_fp):
STF f31, FP_31(r3) STF f31, FP_31(r3)
mffs f2 mffs f2
STF f2, FP_FPSCR(r3) STF f2, FP_FPSCR(r3)
bne 1f
mtmsr r4
isync
1:
#endif #endif
blr blr
@@ -217,6 +232,16 @@ PROC (_CPU_Context_save_fp):
PROC (_CPU_Context_restore_fp): PROC (_CPU_Context_restore_fp):
#if (PPC_HAS_FPU == 1) #if (PPC_HAS_FPU == 1)
lwz r3, 0(r3) lwz r3, 0(r3)
/* A FP context switch may occur in an ISR or exception handler when the FPU is not
* available. Therefore, we must explicitely enable it here!
*/
mfmsr r4
andi. r5,r4,MSR_FP
bne 1f
ori r5,r4,MSR_FP
mtmsr r5
isync
1:
LDF f2, FP_FPSCR(r3) LDF f2, FP_FPSCR(r3)
mtfsf 255, f2 mtfsf 255, f2
LDF f0, FP_0(r3) LDF f0, FP_0(r3)
@@ -251,6 +276,10 @@ PROC (_CPU_Context_restore_fp):
LDF f29, FP_29(r3) LDF f29, FP_29(r3)
LDF f30, FP_30(r3) LDF f30, FP_30(r3)
LDF f31, FP_31(r3) LDF f31, FP_31(r3)
bne 1f
mtmsr r4
isync
1:
#endif #endif
blr blr