Hi,
i have a powerpc cpu (mpc5200) running linux 3.14.17 with xenomai patch
2.6.4 on it. I use floating point in kernel, so the (assembly-)function
"giveup_fpu" (in file arch/powerpc/kernel/fpu.S) is called and throws a
kernel-oops. fpu.S is patched with ipipe-core-3.14.17-powerpc-6.patch.
In original linux (kernel 3.14.17) "giveup_fpu" looks like this:
_GLOBAL(giveup_fpu)
mfmsr r5
ori r5,r5,MSR_FP
#ifdef CONFIG_VSX
BEGIN_FTR_SECTION
oris r5,r5,MSR_VSX@h
END_FTR_SECTION_IFSET(CPU_FTR_VSX)
#endif
SYNC_601
ISYNC_601
MTMSRD(r5) /* enable use of fpu now */
SYNC_601
isync
PPC_LCMPI 0,r3,0
beqlr- /* if no previous owner, done */
addi r3,r3,THREAD /* want THREAD of task */
PPC_LL r6,THREAD_FPSAVEAREA(r3)
PPC_LL r5,PT_REGS(r3)
PPC_LCMPI 0,r6,0
bne 2f
addi r6,r3,THREAD_FPSTATE
2: PPC_LCMPI 0,r5,0
SAVE_32FPVSRS(0, R4, R6)
mffs fr0
stfd fr0,FPSTATE_FPSCR(r6)
beq 1f
PPC_LL r4,_MSR-STACK_FRAME_OVERHEAD(r5)
li r3,MSR_FP|MSR_FE0|MSR_FE1
#ifdef CONFIG_VSX
BEGIN_FTR_SECTION
oris r3,r3,MSR_VSX@h
END_FTR_SECTION_IFSET(CPU_FTR_VSX)
#endif
andc r4,r4,r3 /* disable FP for previous task */
PPC_STL r4,_MSR-STACK_FRAME_OVERHEAD(r5)
1:
#ifndef CONFIG_SMP
li r5,0
LOAD_REG_ADDRBASE(r4,last_task_used_math)
PPC_STL r5,ADDROFF(last_task_used_math)(r4)
#endif /* CONFIG_SMP */
blr
After ipipe patch it looks like this:
_GLOBAL(giveup_fpu)
#ifdef CONFIG_IPIPE
mfmsr r6
#ifdef CONFIG_PPC64
rldicl r5,r6,48,1 /* clear MSR_EE */
rotldi r5,r5,16
#else
rlwinm r5,r6,0,17,15 /* clear MSR_EE */
#endif
#else
mfmsr r5
#endif
ori r5,r5,MSR_FP
#ifdef CONFIG_VSX
BEGIN_FTR_SECTION
oris r5,r5,MSR_VSX@h
END_FTR_SECTION_IFSET(CPU_FTR_VSX)
#endif
SYNC_601
ISYNC_601
MTMSRD(r5) /* enable use of fpu now */
SYNC_601
isync
PPC_LCMPI 0,r3,0
beq- 2f /* if no previous owner, done */
addi r3,r3,THREAD /* want THREAD of task */
PPC_LL r6,THREAD_FPSAVEAREA(r3)
PPC_LL r5,PT_REGS(r3)
PPC_LCMPI 0,r6,0
bne 2f
addi r6,r3,THREAD_FPSTATE
2: PPC_LCMPI 0,r5,0
SAVE_32FPVSRS(0, R4, R6)
mffs fr0
stfd fr0,FPSTATE_FPSCR(r6)
beq 1f
PPC_LL r4,_MSR-STACK_FRAME_OVERHEAD(r5)
li r3,MSR_FP|MSR_FE0|MSR_FE1
#ifdef CONFIG_VSX
BEGIN_FTR_SECTION
oris r3,r3,MSR_VSX@h
END_FTR_SECTION_IFSET(CPU_FTR_VSX)
#endif
andc r4,r4,r3 /* disable FP for previous task */
PPC_STL r4,_MSR-STACK_FRAME_OVERHEAD(r5)
1:
#ifndef CONFIG_SMP
li r5,0
LOAD_REG_ADDRBASE(r4,last_task_used_math)
PPC_STL r5,ADDROFF(last_task_used_math)(r4)
#endif /* CONFIG_SMP */
2:
#ifdef CONFIG_IPIPE /* restore interrupt state */
andi. r6,r6,MSR_EE
beqlr
mfmsr r5
ori r5,r5,MSR_EE
SYNC_601
ISYNC_601
MTMSRD(r5)
SYNC_601
isync
#endif
blr
Tests have shown, that the reuse of the label "2" is the problem. If i
change "giveup_fpu" in the following way, no problems occurs:
GLOBAL(giveup_fpu)
#ifdef CONFIG_IPIPE
mfmsr r6
#ifdef CONFIG_PPC64
rldicl r5,r6,48,1 /* clear MSR_EE */
rotldi r5,r5,16
#else
rlwinm r5,r6,0,17,15 /* clear MSR_EE */
#endif
#else
mfmsr r5
#endif
ori r5,r5,MSR_FP
#ifdef CONFIG_VSX
BEGIN_FTR_SECTION
oris r5,r5,MSR_VSX@h
END_FTR_SECTION_IFSET(CPU_FTR_VSX)
#endif
SYNC_601
ISYNC_601
MTMSRD(r5) /* enable use of fpu now */
SYNC_601
isync
PPC_LCMPI 0,r3,0
beq- 3f /* if no previous owner, done */
addi r3,r3,THREAD /* want THREAD of task */
PPC_LL r6,THREAD_FPSAVEAREA(r3)
PPC_LL r5,PT_REGS(r3)
PPC_LCMPI 0,r6,0
bne 2f
addi r6,r3,THREAD_FPSTATE
2: PPC_LCMPI 0,r5,0
SAVE_32FPVSRS(0, R4, R6)
mffs fr0
stfd fr0,FPSTATE_FPSCR(r6)
beq 1f
PPC_LL r4,_MSR-STACK_FRAME_OVERHEAD(r5)
li r3,MSR_FP|MSR_FE0|MSR_FE1
#ifdef CONFIG_VSX
BEGIN_FTR_SECTION
oris r3,r3,MSR_VSX@h
END_FTR_SECTION_IFSET(CPU_FTR_VSX)
#endif
andc r4,r4,r3 /* disable FP for previous task */
PPC_STL r4,_MSR-STACK_FRAME_OVERHEAD(r5)
1:
#ifndef CONFIG_SMP
li r5,0
LOAD_REG_ADDRBASE(r4,last_task_used_math)
PPC_STL r5,ADDROFF(last_task_used_math)(r4)
#endif /* CONFIG_SMP */
3:
#ifdef CONFIG_IPIPE /* restore interrupt state */
andi. r6,r6,MSR_EE
beqlr
mfmsr r5
ori r5,r5,MSR_EE
SYNC_601
ISYNC_601W
MTMSRD(r5)
SYNC_601
isync
#endif
blr
Is this the right way to solve this problem? If yes, what should i do so
that it comes in the next ipipe patch?
Best regards
Ralf Moder
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