Le 02/09/2024 à 16:00, Jason A. Donenfeld a écrit :
On Mon, Sep 02, 2024 at 03:12:47PM +0200, Christophe Leroy wrote:Le 02/09/2024 à 14:41, Jason A. Donenfeld a écrit :On Mon, Sep 02, 2024 at 02:04:42PM +0200, Christophe Leroy wrote:SYM_FUNC_START(__arch_chacha20_blocks_nostack) #ifdef __powerpc64__ - blr + std r5, -216(r1) + + std r14, -144(r1) + std r15, -136(r1) + std r16, -128(r1) + std r17, -120(r1) + std r18, -112(r1) + std r19, -104(r1) + std r20, -96(r1) + std r21, -88(r1) + std r22, -80(r1) + std r23, -72(r1) + std r24, -64(r1) + std r25, -56(r1) + std r26, -48(r1) + std r27, -40(r1) + std r28, -32(r1) + std r29, -24(r1) + std r30, -16(r1) + std r31, -8(r1) #else stwu r1, -96(r1) stw r5, 20(r1) +#ifdef __BIG_ENDIAN__ stmw r14, 24(r1) +#else + stw r14, 24(r1) + stw r15, 28(r1) + stw r16, 32(r1) + stw r17, 36(r1) + stw r18, 40(r1) + stw r19, 44(r1) + stw r20, 48(r1) + stw r21, 52(r1) + stw r22, 56(r1) + stw r23, 60(r1) + stw r24, 64(r1) + stw r25, 68(r1) + stw r26, 72(r1) + stw r27, 76(r1) + stw r28, 80(r1) + stw r29, 84(r1) + stw r30, 88(r1) + stw r31, 92(r1) +#endif +#endifThis confuses me. Why are you adding code to the !__powerpc64__ branch in this commit? (Also, why does stmw not work on LE?)That's for the VDSO32 ie running 32 bits binaries on a 64 bits kernel. "Programming Environments Manual for 32-Bit Implementations of the PowerPC™ Architecture" say: In some implementations operating with little-endian byte order, execution of an lmw or stmw instruction causes the system alignment error handler to be invoked And GCC doesn't like it either: tools/arch/powerpc/vdso/vgetrandom-chacha.S:84: Error: `stmw' invalid when little-endianDoes it make sense to do all the 32-bit stuff in the PPC32 commit (and then you can introduce the selftests there without the error you mentioned), and then add the 64-bit stuff in this commit?
Can do that, but there will still be a problem with chacha selftests if I don't opt-out the entire function content when it is ppc64. It will build properly but if someone runs it on a ppc64 it will likely crash because only the low 32 bits of registers will be saved.
That's the reason why I really prefered the approach where I set something in vdso_config.h so that the assembly is used only for powerpc32 and when building powerpc64 the assembly part is kept out and vdso_test_chacha simply tells it is not supported.
Christophe
