On Mon, Sep 02, 2024 at 02:04:41PM +0200, Christophe Leroy wrote: > This first patch adds support for PPC32. As selftests cannot easily > be generated only for PPC32, and because the following patch brings > support for PPC64 anyway, this patch opts out all code in > __arch_chacha20_blocks_nostack() so that vdso_test_chacha will not > fail to compile and will not crash on PPC64/PPC64LE, allthough the > selftest itself will fail. This patch also adds a dummy > __kernel_getrandom() function that returns ENOSYS on PPC64 so that > vdso_test_getrandom returns KSFT_SKIP instead of KSFT_FAIL.
Why not just wire up the selftests in the next patch like you did for v3? This seems like extra stuff for no huge reason? > arch/powerpc/Kconfig | 1 + > arch/powerpc/include/asm/vdso/getrandom.h | 54 +++++ > arch/powerpc/include/asm/vdso/vsyscall.h | 6 + > arch/powerpc/include/asm/vdso_datapage.h | 2 + > arch/powerpc/kernel/asm-offsets.c | 1 + > arch/powerpc/kernel/vdso/Makefile | 13 +- > arch/powerpc/kernel/vdso/getrandom.S | 58 ++++++ > arch/powerpc/kernel/vdso/vdso32.lds.S | 1 + > arch/powerpc/kernel/vdso/vdso64.lds.S | 1 + > arch/powerpc/kernel/vdso/vgetrandom-chacha.S | 207 +++++++++++++++++++ > arch/powerpc/kernel/vdso/vgetrandom.c | 16 ++ > tools/testing/selftests/vDSO/Makefile | 2 +- > 12 files changed, 359 insertions(+), 3 deletions(-) > create mode 100644 arch/powerpc/include/asm/vdso/getrandom.h > create mode 100644 arch/powerpc/kernel/vdso/getrandom.S > create mode 100644 arch/powerpc/kernel/vdso/vgetrandom-chacha.S > create mode 100644 arch/powerpc/kernel/vdso/vgetrandom.c I think you might have forgotten to add the symlink in this commit (or the next one, per my comment above, if you agree with it). > +/* > + * Very basic 32 bits implementation of ChaCha20. Produces a given positive > number > + * of blocks of output with a nonce of 0, taking an input key and 8-byte > + * counter. Importantly does not spill to the stack. Its arguments are: > + * > + * r3: output bytes > + * r4: 32-byte key input > + * r5: 8-byte counter input/output (saved on stack) > + * r6: number of 64-byte blocks to write to output > + * > + * r0: counter of blocks (initialised with r6) > + * r4: Value '4' after key has been read. > + * r5-r12: key > + * r14-r15: counter > + * r16-r31: state > + */ > +SYM_FUNC_START(__arch_chacha20_blocks_nostack) > +#ifdef __powerpc64__ > + blr > +#else > + stwu r1, -96(r1) > + stw r5, 20(r1) > + stmw r14, 24(r1) > + > + lwz r14, 0(r5) > + lwz r15, 4(r5) > + mr r0, r6 > + subi r3, r3, 4 > + > + lwz r5, 0(r4) > + lwz r6, 4(r4) > + lwz r7, 8(r4) > + lwz r8, 12(r4) > + lwz r9, 16(r4) > + lwz r10, 20(r4) > + lwz r11, 24(r4) > + lwz r12, 28(r4) If you don't want to do this, don't worry about it, but while I'm commenting on things, I think it's worth noting that x86, loongarch, and arm64 implementations all use the preprocessor or macros to give names to these registers -- state1,2,3,...copy1,2,3 and so forth. Might be worth doing the same if you think there's an easy and obvious way of doing it. If not -- or if that kind of work abhors you -- don't worry about it, as I'm confident enough that this code works fine. But it might be "nice to have". Up to you. > + > + li r4, 4 > +.Lblock: > + li r31, 10 > + Maybe a comment here, "expand 32-byte k" or similar. > + lis r16, 0x6170 > + lis r17, 0x3320 > + lis r18, 0x7962 > + lis r19, 0x6b20 > + addi r16, r16, 0x7865 > + addi r17, r17, 0x646e > + addi r18, r18, 0x2d32 > + addi r19, r19, 0x6574 > + > + mtctr r31 > + > + mr r20, r5 > + mr r21, r6 > + mr r22, r7 > + mr r23, r8 > + mr r24, r9 > + mr r25, r10 > + mr r26, r11 > + mr r27, r12 > + > + mr r28, r14 > + mr r29, r15 > + li r30, 0 > + li r31, 0 > + > +.Lpermute: > + QUARTERROUND4( 0, 4, 8,12, 1, 5, 9,13, 2, 6,10,14, 3, 7,11,15) > + QUARTERROUND4( 0, 5,10,15, 1, 6,11,12, 2, 7, 8,13, 3, 4, 9,14) > + > + bdnz .Lpermute > + > + addis r16, r16, 0x6170 > + addis r17, r17, 0x3320 > + addis r18, r18, 0x7962 > + addis r19, r19, 0x6b20 > + addi r16, r16, 0x7865 > + addi r17, r17, 0x646e > + addi r18, r18, 0x2d32 > + addi r19, r19, 0x6574 > + > + add r20, r20, r5 > + add r21, r21, r6 > + add r22, r22, r7 > + add r23, r23, r8 > + add r24, r24, r9 > + add r25, r25, r10 > + add r26, r26, r11 > + add r27, r27, r12 > + > + add r28, r28, r14 > + add r29, r29, r15 > + > + stwbrx r16, r4, r3 > + addi r3, r3, 8 > + stwbrx r17, 0, r3 > + stwbrx r18, r4, r3 > + addi r3, r3, 8 > + stwbrx r19, 0, r3 > + stwbrx r20, r4, r3 > + addi r3, r3, 8 > + stwbrx r21, 0, r3 > + stwbrx r22, r4, r3 > + addi r3, r3, 8 > + stwbrx r23, 0, r3 > + stwbrx r24, r4, r3 > + addi r3, r3, 8 > + stwbrx r25, 0, r3 > + stwbrx r26, r4, r3 > + addi r3, r3, 8 > + stwbrx r27, 0, r3 > + stwbrx r28, r4, r3 > + addi r3, r3, 8 > + stwbrx r29, 0, r3 > + stwbrx r30, r4, r3 > + addi r3, r3, 8 > + stwbrx r31, 0, r3 > + > + subic. r0, r0, 1 /* subi. can't use r0 as source */ Never seen the period suffix. Just looked this up. Neat.
