Messages in this thread | | | From | Michael Ellerman <> | Subject | RE: [RFC PATCH] powerpc: Convert ____flush_dcache_icache_phys() to C | Date | Mon, 02 Sep 2019 11:48:59 +1000 |
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"Alastair D'Silva" <alastair@au1.ibm.com> writes: > On Wed, 2019-08-21 at 22:27 +0200, Christophe Leroy wrote: >> >> Le 20/08/2019 à 06:36, Alastair D'Silva a écrit : >> > On Fri, 2019-08-16 at 15:52 +0000, Christophe Leroy wrote: >> >> [...] >> >> > >> > Thanks Christophe, >> > >> > I'm trying a somewhat different approach that requires less >> > knowledge >> > of assembler. Handling of CPU_FTR_COHERENT_ICACHE is outside this >> > function. The code below is not a patch as my tree is a bit messy, >> > sorry: >> >> Can we be 100% sure that GCC won't add any code accessing some >> global data or stack while the Data MMU is OFF ? > > +mpe > > I'm not sure how we would go about making such a guarantee, but I've > tied every variable used to a register and addr is passed in a > register, so there is no stack usage, and every call in there only > operates on it's operands.
That's not safe, I can believe it happens to work but the compiler people will laugh at us if it ever breaks.
Let's leave it in asm.
cheers
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