| Message ID | 2a081f1fff5e40f496153f8e0162fc7ec5adab2e.1724309198.git.christophe.leroy@csgroup.eu |
|---|---|
| State | New |
| Headers | show |
| Series | Wire up getrandom() vDSO implementation on powerpc | expand |
On Thu, Aug 22, 2024 at 09:13:10AM +0200, Christophe Leroy wrote: > diff --git a/arch/x86/include/asm/pvclock.h b/arch/x86/include/asm/pvclock.h > index 0c92db84469d..6e4f8fae3ce9 100644 > --- a/arch/x86/include/asm/pvclock.h > +++ b/arch/x86/include/asm/pvclock.h > @@ -5,6 +5,7 @@ > #include <asm/clocksource.h> > #include <asm/pvclock-abi.h> > > +struct timespec64; > /* some helper functions for xen and kvm pv clock sources */ > u64 pvclock_clocksource_read(struct pvclock_vcpu_time_info *src); > u64 pvclock_clocksource_read_nowd(struct pvclock_vcpu_time_info *src); This change isn't mentioned in the commit message and could probably benefit from doing so. > diff --git a/lib/vdso/getrandom.c b/lib/vdso/getrandom.c > index b230f0b10832..cab153c5f9be 100644 > --- a/lib/vdso/getrandom.c > +++ b/lib/vdso/getrandom.c > @@ -3,15 +3,13 @@ > * Copyright (C) 2022-2024 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved. > */ > > -#include <linux/cache.h> > -#include <linux/kernel.h> > -#include <linux/time64.h> > +#include <linux/minmax.h> > #include <vdso/datapage.h> > #include <vdso/getrandom.h> > +#include <vdso/unaligned.h> Ah, that's where you do it. Ignore my comment on the previous commit, then. > #include <asm/vdso/getrandom.h> > -#include <asm/vdso/vsyscall.h> > -#include <asm/unaligned.h> > #include <uapi/linux/mman.h> > +#include <uapi/linux/random.h> > > #define MEMCPY_AND_ZERO_SRC(type, dst, src, len) do { \ > while (len >= sizeof(type)) { \ > @@ -23,6 +21,9 @@ > } \ > } while (0) > > +#define _PAGE_SIZE (1UL << CONFIG_PAGE_SHIFT) > +#define _PAGE_MASK (~(_PAGE_SIZE - 1)) If PAGE_SIZE isn't defined at this point, why not just call it PAGE_SIZE instead of _PAGE_SIZE? But if that's the case, why not put the vdso definition of PAGE_SIZE into some vdso header included by this file?
Le 26/08/2024 à 10:07, Jason A. Donenfeld a écrit : > On Thu, Aug 22, 2024 at 09:13:10AM +0200, Christophe Leroy wrote: >> >> +#define _PAGE_SIZE (1UL << CONFIG_PAGE_SHIFT) >> +#define _PAGE_MASK (~(_PAGE_SIZE - 1)) > > If PAGE_SIZE isn't defined at this point, why not just call it PAGE_SIZE > instead of _PAGE_SIZE? But if that's the case, why not put the vdso > definition of PAGE_SIZE into some vdso header included by this file? It was working ok on powerpc but on x86 I got: CC arch/x86/entry/vdso/vgetrandom.o In file included from arch/x86/entry/vdso/vgetrandom.c:7: arch/x86/entry/vdso/../../../../lib/vdso/getrandom.c:24: error: "PAGE_SIZE" redefined [-Werror] 24 | #define PAGE_SIZE (1UL << CONFIG_PAGE_SHIFT) | In file included from ./arch/x86/include/asm/page.h:9, from ./arch/x86/include/asm/thread_info.h:12, from ./include/linux/thread_info.h:60, from ./include/linux/smp.h:118, from ./include/linux/alloc_tag.h:14, from ./include/linux/percpu.h:5, from ./arch/x86/include/asm/msr.h:15, from ./arch/x86/include/asm/vdso/gettimeofday.h:19, from ./include/vdso/datapage.h:164, from arch/x86/entry/vdso/../../../../lib/vdso/getrandom.c:7, from arch/x86/entry/vdso/vgetrandom.c:7: ./arch/x86/include/asm/page_types.h:11: note: this is the location of the previous definition 11 | #define PAGE_SIZE (_AC(1,UL) << PAGE_SHIFT) | In file included from arch/x86/entry/vdso/vgetrandom.c:7: arch/x86/entry/vdso/../../../../lib/vdso/getrandom.c:25: error: "PAGE_MASK" redefined [-Werror] 25 | #define PAGE_MASK (~(PAGE_SIZE - 1)) | In file included from ./arch/x86/include/asm/page.h:9, from ./arch/x86/include/asm/thread_info.h:12, from ./include/linux/thread_info.h:60, from ./include/linux/smp.h:118, from ./include/linux/alloc_tag.h:14, from ./include/linux/percpu.h:5, from ./arch/x86/include/asm/msr.h:15, from ./arch/x86/include/asm/vdso/gettimeofday.h:19, from ./include/vdso/datapage.h:164, from arch/x86/entry/vdso/../../../../lib/vdso/getrandom.c:7, from arch/x86/entry/vdso/vgetrandom.c:7: ./arch/x86/include/asm/page_types.h:12: note: this is the location of the previous definition 12 | #define PAGE_MASK (~(PAGE_SIZE-1)) | cc1: all warnings being treated as errors Christophe
On Mon, Aug 26, 2024 at 10:37:49AM +0200, Christophe Leroy wrote: > > > Le 26/08/2024 à 10:07, Jason A. Donenfeld a écrit : > > On Thu, Aug 22, 2024 at 09:13:10AM +0200, Christophe Leroy wrote: > >> > >> +#define _PAGE_SIZE (1UL << CONFIG_PAGE_SHIFT) > >> +#define _PAGE_MASK (~(_PAGE_SIZE - 1)) > > > > If PAGE_SIZE isn't defined at this point, why not just call it PAGE_SIZE > > instead of _PAGE_SIZE? But if that's the case, why not put the vdso > > definition of PAGE_SIZE into some vdso header included by this file? > > It was working ok on powerpc but on x86 I got: Seems like there might be some more fiddling to do, then? Or did you conclude it's impossible?
Le 26/08/2024 à 10:58, Jason A. Donenfeld a écrit : > On Mon, Aug 26, 2024 at 10:37:49AM +0200, Christophe Leroy wrote: >> >> >> Le 26/08/2024 à 10:07, Jason A. Donenfeld a écrit : >>> On Thu, Aug 22, 2024 at 09:13:10AM +0200, Christophe Leroy wrote: >>>> >>>> +#define _PAGE_SIZE (1UL << CONFIG_PAGE_SHIFT) >>>> +#define _PAGE_MASK (~(_PAGE_SIZE - 1)) >>> >>> If PAGE_SIZE isn't defined at this point, why not just call it PAGE_SIZE >>> instead of _PAGE_SIZE? But if that's the case, why not put the vdso >>> definition of PAGE_SIZE into some vdso header included by this file? >> >> It was working ok on powerpc but on x86 I got: > > Seems like there might be some more fiddling to do, then? Or did you > conclude it's impossible? Maybe someone who knows x86 in details could helps but after a first look I gave up because it looks very x86 specific, indeed that's x86/asm/vdso/gettimeofday.h that pulls several x86/asm/ headers , and the same type of issue might arise for any new architecture coming in. For me it looked cleaner to just do as commit cffaefd15a8f ("vdso: Use CONFIG_PAGE_SHIFT in vdso/datapage.h") and not use PAGE_SIZE at all. But I didn't want to directly use (1UL << CONFIG_PAGE_SHIFT) and (~(1UL << (CONFIG_PAGE_SHIFT - 1))) in the code directly hence the new macros with a leading underscore to avoid any conflict with existing macros. Christophe
On Mon, Aug 26, 2024 at 12:45:40PM +0200, Christophe Leroy wrote: > > > Le 26/08/2024 à 10:58, Jason A. Donenfeld a écrit : > > On Mon, Aug 26, 2024 at 10:37:49AM +0200, Christophe Leroy wrote: > >> > >> > >> Le 26/08/2024 à 10:07, Jason A. Donenfeld a écrit : > >>> On Thu, Aug 22, 2024 at 09:13:10AM +0200, Christophe Leroy wrote: > >>>> > >>>> +#define _PAGE_SIZE (1UL << CONFIG_PAGE_SHIFT) > >>>> +#define _PAGE_MASK (~(_PAGE_SIZE - 1)) > >>> > >>> If PAGE_SIZE isn't defined at this point, why not just call it PAGE_SIZE > >>> instead of _PAGE_SIZE? But if that's the case, why not put the vdso > >>> definition of PAGE_SIZE into some vdso header included by this file? > >> > >> It was working ok on powerpc but on x86 I got: > > > > Seems like there might be some more fiddling to do, then? Or did you > > conclude it's impossible? > > Maybe someone who knows x86 in details could helps but after a first > look I gave up because it looks very x86 specific, indeed that's > x86/asm/vdso/gettimeofday.h that pulls several x86/asm/ headers , and > the same type of issue might arise for any new architecture coming in. > > For me it looked cleaner to just do as commit cffaefd15a8f ("vdso: Use > CONFIG_PAGE_SHIFT in vdso/datapage.h") and not use PAGE_SIZE at all. But > I didn't want to directly use (1UL << CONFIG_PAGE_SHIFT) and (~(1UL << > (CONFIG_PAGE_SHIFT - 1))) in the code directly hence the new macros with > a leading underscore to avoid any conflict with existing macros. If that's the case and you can't sort it out or it's impossible, then it seems like adding #ifndef PAGE_SIZE, #define... inside of some vdso header (not inside getrandom.c) would make sense. Jason
On Mon, Aug 26 2024 at 12:45, Christophe Leroy wrote: > Le 26/08/2024 à 10:58, Jason A. Donenfeld a écrit : >> On Mon, Aug 26, 2024 at 10:37:49AM +0200, Christophe Leroy wrote: >>> >>> >>> Le 26/08/2024 à 10:07, Jason A. Donenfeld a écrit : >>>> On Thu, Aug 22, 2024 at 09:13:10AM +0200, Christophe Leroy wrote: >>>>> >>>>> +#define _PAGE_SIZE (1UL << CONFIG_PAGE_SHIFT) >>>>> +#define _PAGE_MASK (~(_PAGE_SIZE - 1)) >>>> >>>> If PAGE_SIZE isn't defined at this point, why not just call it PAGE_SIZE >>>> instead of _PAGE_SIZE? But if that's the case, why not put the vdso >>>> definition of PAGE_SIZE into some vdso header included by this file? >>> >>> It was working ok on powerpc but on x86 I got: >> >> Seems like there might be some more fiddling to do, then? Or did you >> conclude it's impossible? > > Maybe someone who knows x86 in details could helps but after a first > look I gave up because it looks very x86 specific, indeed that's > x86/asm/vdso/gettimeofday.h that pulls several x86/asm/ headers , and > the same type of issue might arise for any new architecture coming in. Of course :) > For me it looked cleaner to just do as commit cffaefd15a8f ("vdso: Use > CONFIG_PAGE_SHIFT in vdso/datapage.h") and not use PAGE_SIZE at all. But > I didn't want to directly use (1UL << CONFIG_PAGE_SHIFT) and (~(1UL << > (CONFIG_PAGE_SHIFT - 1))) in the code directly hence the new macros with > a leading underscore to avoid any conflict with existing macros. #ifndef PAGE_SIZE # define #endif Perhaps? Thanks, tglx
diff --git a/arch/x86/include/asm/pvclock.h b/arch/x86/include/asm/pvclock.h index 0c92db84469d..6e4f8fae3ce9 100644 --- a/arch/x86/include/asm/pvclock.h +++ b/arch/x86/include/asm/pvclock.h @@ -5,6 +5,7 @@ #include <asm/clocksource.h> #include <asm/pvclock-abi.h> +struct timespec64; /* some helper functions for xen and kvm pv clock sources */ u64 pvclock_clocksource_read(struct pvclock_vcpu_time_info *src); u64 pvclock_clocksource_read_nowd(struct pvclock_vcpu_time_info *src); diff --git a/include/vdso/helpers.h b/include/vdso/helpers.h index 73501149439d..3ddb03bb05cb 100644 --- a/include/vdso/helpers.h +++ b/include/vdso/helpers.h @@ -4,6 +4,7 @@ #ifndef __ASSEMBLY__ +#include <asm/barrier.h> #include <vdso/datapage.h> static __always_inline u32 vdso_read_begin(const struct vdso_data *vd) diff --git a/lib/vdso/getrandom.c b/lib/vdso/getrandom.c index b230f0b10832..cab153c5f9be 100644 --- a/lib/vdso/getrandom.c +++ b/lib/vdso/getrandom.c @@ -3,15 +3,13 @@ * Copyright (C) 2022-2024 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved. */ -#include <linux/cache.h> -#include <linux/kernel.h> -#include <linux/time64.h> +#include <linux/minmax.h> #include <vdso/datapage.h> #include <vdso/getrandom.h> +#include <vdso/unaligned.h> #include <asm/vdso/getrandom.h> -#include <asm/vdso/vsyscall.h> -#include <asm/unaligned.h> #include <uapi/linux/mman.h> +#include <uapi/linux/random.h> #define MEMCPY_AND_ZERO_SRC(type, dst, src, len) do { \ while (len >= sizeof(type)) { \ @@ -23,6 +21,9 @@ } \ } while (0) +#define _PAGE_SIZE (1UL << CONFIG_PAGE_SHIFT) +#define _PAGE_MASK (~(_PAGE_SIZE - 1)) + static void memcpy_and_zero_src(void *dst, void *src, size_t len) { if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) { @@ -64,7 +65,7 @@ static __always_inline ssize_t __cvdso_getrandom_data(const struct vdso_rng_data *rng_info, void *buffer, size_t len, unsigned int flags, void *opaque_state, size_t opaque_len) { - ssize_t ret = min_t(size_t, INT_MAX & PAGE_MASK /* = MAX_RW_COUNT */, len); + ssize_t ret = min_t(size_t, INT_MAX & _PAGE_MASK /* = MAX_RW_COUNT */, len); struct vgetrandom_state *state = opaque_state; size_t batch_len, nblocks, orig_len = len; bool in_use, have_retried = false; @@ -82,7 +83,7 @@ __cvdso_getrandom_data(const struct vdso_rng_data *rng_info, void *buffer, size_ } /* The state must not straddle a page, since pages can be zeroed at any time. */ - if (unlikely(((unsigned long)opaque_state & ~PAGE_MASK) + sizeof(*state) > PAGE_SIZE)) + if (unlikely(((unsigned long)opaque_state & ~_PAGE_MASK) + sizeof(*state) > _PAGE_SIZE)) return -EFAULT; /* If the caller passes the wrong size, which might happen due to CRIU, fallback. */
Building a VDSO32 on a 64 bits kernel is problematic when some system headers are included. See commit 8c59ab839f52 ("lib/vdso: Enable common headers") for more details. Minimise the amount of headers by moving needed items into dedicated common headers. For PAGE_SIZE and PAGE_MASK, redefine them from CONFIG_PAGE_SHIFT in the same way as commit cffaefd15a8f ("vdso: Use CONFIG_PAGE_SHIFT in vdso/datapage.h") Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> --- arch/x86/include/asm/pvclock.h | 1 + include/vdso/helpers.h | 1 + lib/vdso/getrandom.c | 15 ++++++++------- 3 files changed, 10 insertions(+), 7 deletions(-)