xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

powerpc/6xx: Don't use SPRN_SPRG2 for storing stack pointer while in RTAS

Browse Source 
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>
This commit is contained in:
Christophe Leroy
2019-02-21 10:37:54 +00:00
committed by Michael Ellerman
parent 40058337f2
commit 0df977eafc
5 changed files with 21 additions and 13 deletions
Download Patch File Download Diff File Expand all files Collapse all files

22
arch/powerpc/kernel/head_32.S
View File

@@ -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