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
>
> Can you figure out what's going on and send a fix, which I'll squash
> into this commit?
This doesn't work, but I wonder if something like it is what we want. I
need to head out for the day, but here's what I've got. It's all wrong
but might be of interest.
diff --git a/arch/powerpc/include/asm/vdso/getrandom.h b/arch/powerpc/include/asm/vdso/getrandom.h
index 501d6bb14e8a..acb271709d30 100644
--- a/arch/powerpc/include/asm/vdso/getrandom.h
+++ b/arch/powerpc/include/asm/vdso/getrandom.h
@@ -47,7 +47,8 @@ static __always_inline struct vdso_rng_data *__arch_get_vdso_rng_data(void)
}
ssize_t __c_kernel_getrandom(void *buffer, size_t len, unsigned int flags, void *opaque_state,
- size_t opaque_len, const struct vdso_rng_data *vd);
+ size_t opaque_len, const struct vdso_data *vd,
+ const struct vdso_rng_data *vrd);
#endif /* !__ASSEMBLY__ */
diff --git a/arch/powerpc/kernel/vdso/getrandom.S b/arch/powerpc/kernel/vdso/getrandom.S
index a957cd2b2b03..bc49eb87cfd1 100644
--- a/arch/powerpc/kernel/vdso/getrandom.S
+++ b/arch/powerpc/kernel/vdso/getrandom.S
@@ -32,7 +32,7 @@
.cfi_rel_offset r2, PPC_MIN_STKFRM + STK_GOT
#endif
get_datapage r8
- addi r8, r8, VDSO_RNG_DATA_OFFSET
+ addi r9, r8, VDSO_RNG_DATA_OFFSET
bl CFUNC(DOTSYM(\funct))
PPC_LL r0, PPC_MIN_STKFRM + PPC_LR_STKOFF(r1)
#ifdef __powerpc64__
diff --git a/arch/powerpc/kernel/vdso/vgetrandom.c b/arch/powerpc/kernel/vdso/vgetrandom.c
index 5f855d45fb7b..408c76036868 100644
--- a/arch/powerpc/kernel/vdso/vgetrandom.c
+++ b/arch/powerpc/kernel/vdso/vgetrandom.c
@@ -8,7 +8,10 @@
#include <linux/types.h>
ssize_t __c_kernel_getrandom(void *buffer, size_t len, unsigned int flags, void *opaque_state,
- size_t opaque_len, const struct vdso_rng_data *vd)
+ size_t opaque_len, const struct vdso_data *vd,
+ const struct vdso_rng_data *vrd)
{
- return __cvdso_getrandom_data(vd, buffer, len, flags, opaque_state, opaque_len);
+ if (IS_ENABLED(CONFIG_TIME_NS) && vd->clock_mode == VDSO_CLOCKMODE_TIMENS)
+ vrd = (void *)vrd + (1UL << CONFIG_PAGE_SHIFT);
+ return __cvdso_getrandom_data(vrd, buffer, len, flags, opaque_state, opaque_len);
}
