[PATCH v3 14/16] powerpc/32: implement fast entry for syscalls on BOOKE

[Christophe Leroy]

Paul,

Le 23/05/2019 à 08:14, Paul Mackerras a écrit :
> On Tue, Apr 30, 2019 at 12:39:03PM +0000, Christophe Leroy wrote:
>> This patch implements a fast entry for syscalls.
>>
>> Syscalls don't have to preserve non volatile registers except LR.
>>
>> This patch then implement a fast entry for syscalls, where
>> volatile registers get clobbered.
>>
>> As this entry is dedicated to syscall it always sets MSR_EE
>> and warns in case MSR_EE was previously off
>>
>> It also assumes that the call is always from user, system calls are
>> unexpected from kernel.
> 
> This is now upstream as commit 1a4b739bbb4f.  On the e500mc test
> config that I use, I'm getting this build failure:
> 
> arch/powerpc/kernel/head_fsl_booke.o: In function `SystemCall':
> arch/powerpc/kernel/head_fsl_booke.S:416: undefined reference to `kvmppc_handler_BOOKE_INTERRUPT_SYSCALL_SPRN_SRR1'
> Makefile:1052: recipe for target 'vmlinux' failed

Does my patch (https://patchwork.ozlabs.org/patch/1103909/) fixes the 
issue for you ?

Thanks
Christophe

> 
>> +.macro SYSCALL_ENTRY trapno intno
>> +	mfspr	r10, SPRN_SPRG_THREAD
>> +#ifdef CONFIG_KVM_BOOKE_HV
>> +BEGIN_FTR_SECTION
>> +	mtspr	SPRN_SPRG_WSCRATCH0, r10
>> +	stw	r11, THREAD_NORMSAVE(0)(r10)
>> +	stw	r13, THREAD_NORMSAVE(2)(r10)
>> +	mfcr	r13			/* save CR in r13 for now	   */
>> +	mfspr	r11, SPRN_SRR1
>> +	mtocrf	0x80, r11	/* check MSR[GS] without clobbering reg */
>> +	bf	3, 1975f
>> +	b	kvmppc_handler_BOOKE_INTERRUPT_\intno\()_SPRN_SRR1
> 
> It seems to me that the "_SPRN_SRR1" on the end of this line
> isn't meant to be there...  However, it still fails to link with that
> removed.
> 
> Paul.
>