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riscv: Implement non-stub __vdso_gettc and __vdso_gettimekeep
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Authored by jrtc27 on Jun 30 2021, 3:08 PM.

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lib/libc/riscv/sys/__vdso_gettc.c
47

Hm, plain csr_read might be more appropriate given the result is put in a u_int, though it's a bit academic given we don't support RV32. The two are the same on RV64 but on RV32 it'll loop until it reads a consistent time and timeh to get a 64-bit value from two 32-bit CSRs and then throw away the upper half.

Use csr_read in place of csr_read64

Thanks! I can confirm that truss no longer shows the clock_gettime() syscalls with this version of the patch.

This revision is now accepted and ready to land.Jun 30 2021, 4:35 PM
mhorne added a subscriber: mhorne.

Thanks for this one.

lib/libc/riscv/sys/__vdso_gettc.c
27

Nit: not required for new files

lib/libc/riscv/sys/__vdso_gettc.c
27

for new files that won't be MFC'd to stable/12..... I don't think this will be, given the riscv support in 12 isn't so good (IIRC, I might be wrong), but thought I'd mention in case I am wrong.

lib/libc/riscv/sys/__vdso_gettc.c
27

That's right, there's no point bringing this past stable/13, but the precision is helpful.