On Thu, Sep 05, 2024 at 06:13:29PM +0200, Jason A. Donenfeld wrote:
+/*
- The macro sets two stack frames, one for the caller and one for the callee
- because there are no requirement for the caller to set a stack frame when
- calling VDSO so it may have omitted to set one, especially on PPC64
- */
+.macro cvdso_call funct
- .cfi_startproc
- PPC_STLU r1, -PPC_MIN_STKFRM(r1)
- .cfi_adjust_cfa_offset PPC_MIN_STKFRM
- mflr r0
- PPC_STLU r1, -PPC_MIN_STKFRM(r1)
- .cfi_adjust_cfa_offset PPC_MIN_STKFRM
- PPC_STL r0, PPC_MIN_STKFRM + PPC_LR_STKOFF(r1)
- .cfi_rel_offset lr, PPC_MIN_STKFRM + PPC_LR_STKOFF
- get_datapage r8
- addi r8, r8, VDSO_RNG_DATA_OFFSET
- bl CFUNC(DOTSYM(\funct))
- PPC_LL r0, PPC_MIN_STKFRM + PPC_LR_STKOFF(r1)
- cmpwi r3, 0
- mtlr r0
- addi r1, r1, 2 * PPC_MIN_STKFRM
- .cfi_restore lr
- .cfi_def_cfa_offset 0
- crclr so
- bgelr+
- crset so
- neg r3, r3
- blr
- .cfi_endproc
+.endm
You wrote in an earlier email that this worked with time namespaces, but in my testing that doesn't seem to be the case.
From my test harness [1]:
Normal single thread vdso: 25000000 times in 12.494133131 seconds libc: 25000000 times in 69.594625188 seconds syscall: 25000000 times in 67.349243972 seconds Time namespace single thread vdso: 25000000 times in 71.673057436 seconds libc: 25000000 times in 71.712774121 seconds syscall: 25000000 times in 66.902318080 seconds
I'm seeing this on ppc, ppc64, and ppc64le.
Can you figure out what's going on and send a fix, which I'll squash into this commit?
Also, FYI, I've verified that things do work on x86_64, loongarch64, arm64, and arm64_be. It's just the ppc archs that are broken. So this test _is_ a good one.