diff options
| author | Christophe Leroy | 2019-02-21 10:37:54 +0000 |
|---|---|---|
| committer | Michael Ellerman | 2019-02-22 00:10:16 +1100 |
| commit | 0df977eafc792a5365a7f81d8d5920132e03afad (patch) | |
| tree | 145c1adc8829075f35bbf51742de3a4430259f0f /arch/powerpc/kernel/head_32.S | |
| parent | 40058337f23f79212f92ed5ef066e90a032905b1 (diff) | |
powerpc/6xx: Don't use SPRN_SPRG2 for storing stack pointer while in RTAS
When calling RTAS, the stack pointer is stored in SPRN_SPRG2
in order to be able to restore it in case of machine check in RTAS.
As machine check is not a perfomance critical path, this patch
frees SPRN_SPRG2 by using a field in thread struct instead.
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch/powerpc/kernel/head_32.S')
| -rw-r--r-- | arch/powerpc/kernel/head_32.S | 22 |
1 files changed, 12 insertions, 10 deletions
diff --git a/arch/powerpc/kernel/head_32.S b/arch/powerpc/kernel/head_32.S index c2f564690778..04128899a0a5 100644 --- a/arch/powerpc/kernel/head_32.S +++ b/arch/powerpc/kernel/head_32.S @@ -352,9 +352,8 @@ i##n: \ * registers that might have bad values includes all the GPRs * and all the BATs. We indicate that we are in RTAS by putting * a non-zero value, the address of the exception frame to use, - * in SPRG2. The machine check handler checks SPRG2 and uses its - * value if it is non-zero. If we ever needed to free up SPRG2, - * we could use a field in the thread_info or thread_struct instead. + * in thread.rtas_sp. The machine check handler checks thread.rtas_sp + * and uses its value if it is non-zero. * (Other exception handlers assume that r1 is a valid kernel stack * pointer when we take an exception from supervisor mode.) * -- paulus. @@ -365,16 +364,15 @@ i##n: \ mtspr SPRN_SPRG_SCRATCH1,r11 mfcr r10 #ifdef CONFIG_PPC_CHRP - mfspr r11,SPRN_SPRG_RTAS - cmpwi 0,r11,0 - bne 7f + mfspr r11, SPRN_SPRG_THREAD + lwz r11, RTAS_SP(r11) + cmpwi cr1, r11, 0 + bne cr1, 7f #endif /* CONFIG_PPC_CHRP */ EXCEPTION_PROLOG_1 7: EXCEPTION_PROLOG_2 addi r3,r1,STACK_FRAME_OVERHEAD #ifdef CONFIG_PPC_CHRP - mfspr r4,SPRN_SPRG_RTAS - cmpwi cr1,r4,0 bne cr1,1f #endif EXC_XFER_STD(0x200, machine_check_exception) @@ -865,8 +863,10 @@ __secondary_start: tophys(r4,r2) addi r4,r4,THREAD /* phys address of our thread_struct */ mtspr SPRN_SPRG_THREAD,r4 +#ifdef CONFIG_PPC_RTAS li r3,0 - mtspr SPRN_SPRG_RTAS,r3 /* 0 => not in RTAS */ + stw r3, RTAS_SP(r4) /* 0 => not in RTAS */ +#endif /* enable MMU and jump to start_secondary */ li r4,MSR_KERNEL @@ -950,8 +950,10 @@ start_here: tophys(r4,r2) addi r4,r4,THREAD /* init task's THREAD */ mtspr SPRN_SPRG_THREAD,r4 +#ifdef CONFIG_PPC_RTAS li r3,0 - mtspr SPRN_SPRG_RTAS,r3 /* 0 => not in RTAS */ + stw r3, RTAS_SP(r4) /* 0 => not in RTAS */ +#endif /* stack */ lis r1,init_thread_union@ha |