Messages in this thread Patch in this message | | | From | Michael Ellerman <> | Subject | Re: [PATCH] powerpc/32: Add missing context synchronisation with CONFIG_VMAP_STACK | Date | Sun, 26 Jan 2020 00:28:04 +1100 |
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Christophe Leroy <christophe.leroy@c-s.fr> writes: > Michael Ellerman <mpe@ellerman.id.au> a écrit : >> Christophe Leroy <christophe.leroy@c-s.fr> writes: ... >>> diff --git a/arch/powerpc/kernel/head_32.h b/arch/powerpc/kernel/head_32.h >>> index 73a035b40dbf..a6a5fbbf8504 100644 >>> --- a/arch/powerpc/kernel/head_32.h >>> +++ b/arch/powerpc/kernel/head_32.h >>> @@ -43,6 +43,7 @@ >>> .ifeq \for_rtas >>> li r11, MSR_KERNEL & ~(MSR_IR | MSR_RI) /* can take DTLB miss */ >>> mtmsr r11 >>> + isync >> >> Actually this one leads to: >> >> /home/michael/linux/arch/powerpc/kernel/head_8xx.S: Assembler messages: >> /home/michael/linux/arch/powerpc/kernel/head_8xx.S:151: Error: >> attempt to move .org backwards >> make[3]: *** [/home/michael/linux/scripts/Makefile.build:348: >> arch/powerpc/kernel/head_8xx.o] Error 1 >> >> For mpc885_ads_defconfig. >> >> That's the alignment exception overflowing into the program check >> handler: >> >> /* Alignment exception */ >> . = 0x600 >> Alignment: >> EXCEPTION_PROLOG handle_dar_dsisr=1 >> save_dar_dsisr_on_stack r4, r5, r11 >> li r6, RPN_PATTERN >> mtspr SPRN_DAR, r6 /* Tag DAR, to be used in DTLB Error */ >> addi r3,r1,STACK_FRAME_OVERHEAD >> EXC_XFER_STD(0x600, alignment_exception) >> >> /* Program check exception */ >> EXCEPTION(0x700, ProgramCheck, program_check_exception, EXC_XFER_STD) >> >> >> Can't see an obvious/easy way to fix it. > > Argh ! > > I think the easiest is to move the EXC_XFER_STD(0x600, > alignment_exception) somewhere else and branch to it. There is some > space at .0xa00
That works, or builds at least. I'm not setup to boot test it.
Does this look OK?
cheers
From 40e7d671aa27cf4411188f978b2cd06b30a9cb6c Mon Sep 17 00:00:00 2001 From: Michael Ellerman <mpe@ellerman.id.au> Date: Sun, 26 Jan 2020 00:20:16 +1100 Subject: [PATCH] powerpc/8xx: Move tail of alignment exception out of line
When we enable VMAP_STACK there will not be enough room for the alignment handler at 0x600 in head_8xx.S. For now move the tail of the alignment handler out of line, and branch to it.
Suggested-by: Christophe Leroy <christophe.leroy@c-s.fr> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> --- arch/powerpc/kernel/head_8xx.S | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S index 477933b36bde..9922306ae512 100644 --- a/arch/powerpc/kernel/head_8xx.S +++ b/arch/powerpc/kernel/head_8xx.S @@ -145,7 +145,7 @@ _ENTRY(_start); li r6, RPN_PATTERN mtspr SPRN_DAR, r6 /* Tag DAR, to be used in DTLB Error */ addi r3,r1,STACK_FRAME_OVERHEAD - EXC_XFER_STD(0x600, alignment_exception) + b .Lalignment_exception_ool /* Program check exception */ EXCEPTION(0x700, ProgramCheck, program_check_exception, EXC_XFER_STD) @@ -153,6 +153,11 @@ _ENTRY(_start); /* Decrementer */ EXCEPTION(0x900, Decrementer, timer_interrupt, EXC_XFER_LITE) + /* With VMAP_STACK there's not enough room for this at 0x600 */ + . = 0xa00 +.Lalignment_exception_ool: + EXC_XFER_STD(0x600, alignment_exception) + /* System call */ . = 0xc00 SystemCall: -- 2.21.1
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