* [PATCH] ACPI: avoid NULL pointer arithmetic
@ 2021-09-27 12:13 Arnd Bergmann
2021-09-28 17:43 ` Rafael J. Wysocki
2021-09-29 18:47 ` Rafael J. Wysocki
0 siblings, 2 replies; 7+ messages in thread
From: Arnd Bergmann @ 2021-09-27 12:13 UTC (permalink / raw)
To: Rafael J. Wysocki, Len Brown, Robert Moore
Cc: Arnd Bergmann, Rafael J. Wysocki, Nathan Chancellor,
Nick Desaulniers, Erik Kaneda, linux-acpi, devel, linux-kernel,
llvm
From: Arnd Bergmann <arnd@arndb.de>
There are some very old macros for doing an open-coded offsetof() and
cast between pointer and integer in ACPI headers. clang-14 now complains
about these:
drivers/acpi/acpica/tbfadt.c:86:3: error: performing pointer subtraction with a null pointer has undefined behavior [-Werror,-Wnull-pointer-subtraction]
ACPI_FADT_OFFSET(pm_timer_block),
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/acpi/actbl.h:376:47: note: expanded from macro 'ACPI_FADT_OFFSET'
#define ACPI_FADT_OFFSET(f) (u16) ACPI_OFFSET (struct acpi_table_fadt, f)
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/acpi/actypes.h:511:41: note: expanded from macro 'ACPI_OFFSET'
#define ACPI_OFFSET(d, f) ACPI_PTR_DIFF (&(((d *) 0)->f), (void *) 0)
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/acpi/actypes.h:505:79: note: expanded from macro 'ACPI_PTR_DIFF'
#define ACPI_PTR_DIFF(a, b) ((acpi_size) (ACPI_CAST_PTR (u8, (a)) - ACPI_CAST_PTR (u8, (b))))
^ ~~~~~~~~~~~~~~~~~~~~~~~
Convert them to the modern equivalents.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
include/acpi/actypes.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/include/acpi/actypes.h b/include/acpi/actypes.h
index 92c71dfce0d5..285bc7b73de3 100644
--- a/include/acpi/actypes.h
+++ b/include/acpi/actypes.h
@@ -507,8 +507,8 @@ typedef u64 acpi_integer;
/* Pointer/Integer type conversions */
#define ACPI_TO_POINTER(i) ACPI_CAST_PTR (void, (acpi_size) (i))
-#define ACPI_TO_INTEGER(p) ACPI_PTR_DIFF (p, (void *) 0)
-#define ACPI_OFFSET(d, f) ACPI_PTR_DIFF (&(((d *) 0)->f), (void *) 0)
+#define ACPI_TO_INTEGER(p) ((uintptr_t)(p))
+#define ACPI_OFFSET(d, f) offsetof(d, f)
#define ACPI_PHYSADDR_TO_PTR(i) ACPI_TO_POINTER(i)
#define ACPI_PTR_TO_PHYSADDR(i) ACPI_TO_INTEGER(i)
--
2.29.2
^ permalink raw reply related [flat|nested] 7+ messages in thread* Re: [PATCH] ACPI: avoid NULL pointer arithmetic
2021-09-27 12:13 [PATCH] ACPI: avoid NULL pointer arithmetic Arnd Bergmann
@ 2021-09-28 17:43 ` Rafael J. Wysocki
2021-09-28 20:39 ` Moore, Robert
2021-09-29 18:47 ` Rafael J. Wysocki
1 sibling, 1 reply; 7+ messages in thread
From: Rafael J. Wysocki @ 2021-09-28 17:43 UTC (permalink / raw)
To: Arnd Bergmann, Robert Moore
Cc: Arnd Bergmann, Nathan Chancellor, Nick Desaulniers, Erik Kaneda,
linux-acpi, devel, linux-kernel, llvm, Len Brown,
Rafael J. Wysocki
Bob, this is ACPICA material.
Would it be possible to apply this to the upstream from the patch or do
you need a PR for this?
On 9/27/2021 2:13 PM, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
>
> There are some very old macros for doing an open-coded offsetof() and
> cast between pointer and integer in ACPI headers. clang-14 now complains
> about these:
>
> drivers/acpi/acpica/tbfadt.c:86:3: error: performing pointer subtraction with a null pointer has undefined behavior [-Werror,-Wnull-pointer-subtraction]
> ACPI_FADT_OFFSET(pm_timer_block),
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> include/acpi/actbl.h:376:47: note: expanded from macro 'ACPI_FADT_OFFSET'
> #define ACPI_FADT_OFFSET(f) (u16) ACPI_OFFSET (struct acpi_table_fadt, f)
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> include/acpi/actypes.h:511:41: note: expanded from macro 'ACPI_OFFSET'
> #define ACPI_OFFSET(d, f) ACPI_PTR_DIFF (&(((d *) 0)->f), (void *) 0)
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> include/acpi/actypes.h:505:79: note: expanded from macro 'ACPI_PTR_DIFF'
> #define ACPI_PTR_DIFF(a, b) ((acpi_size) (ACPI_CAST_PTR (u8, (a)) - ACPI_CAST_PTR (u8, (b))))
> ^ ~~~~~~~~~~~~~~~~~~~~~~~
> Convert them to the modern equivalents.
>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
> include/acpi/actypes.h | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/include/acpi/actypes.h b/include/acpi/actypes.h
> index 92c71dfce0d5..285bc7b73de3 100644
> --- a/include/acpi/actypes.h
> +++ b/include/acpi/actypes.h
> @@ -507,8 +507,8 @@ typedef u64 acpi_integer;
> /* Pointer/Integer type conversions */
>
> #define ACPI_TO_POINTER(i) ACPI_CAST_PTR (void, (acpi_size) (i))
> -#define ACPI_TO_INTEGER(p) ACPI_PTR_DIFF (p, (void *) 0)
> -#define ACPI_OFFSET(d, f) ACPI_PTR_DIFF (&(((d *) 0)->f), (void *) 0)
> +#define ACPI_TO_INTEGER(p) ((uintptr_t)(p))
> +#define ACPI_OFFSET(d, f) offsetof(d, f)
> #define ACPI_PHYSADDR_TO_PTR(i) ACPI_TO_POINTER(i)
> #define ACPI_PTR_TO_PHYSADDR(i) ACPI_TO_INTEGER(i)
>
^ permalink raw reply [flat|nested] 7+ messages in thread
* RE: [PATCH] ACPI: avoid NULL pointer arithmetic
2021-09-28 17:43 ` Rafael J. Wysocki
@ 2021-09-28 20:39 ` Moore, Robert
2021-09-29 12:01 ` Rafael J. Wysocki
0 siblings, 1 reply; 7+ messages in thread
From: Moore, Robert @ 2021-09-28 20:39 UTC (permalink / raw)
To: Wysocki, Rafael J, Arnd Bergmann
Cc: Arnd Bergmann, Nathan Chancellor, Nick Desaulniers, linux-acpi,
devel, linux-kernel, llvm, Len Brown, Rafael J. Wysocki
I can take this patch as-is, I think. I'll try for the next acpica release later this week.
-----Original Message-----
From: Wysocki, Rafael J <rafael.j.wysocki@intel.com>
Sent: Tuesday, September 28, 2021 10:44 AM
To: Arnd Bergmann <arnd@kernel.org>; Moore, Robert <robert.moore@intel.com>
Cc: Arnd Bergmann <arnd@arndb.de>; Nathan Chancellor <nathan@kernel.org>; Nick Desaulniers <ndesaulniers@google.com>; Erik Kaneda <erik.kaneda@intel.com>; linux-acpi@vger.kernel.org; devel@acpica.org; linux-kernel@vger.kernel.org; llvm@lists.linux.dev; Len Brown <lenb@kernel.org>; Rafael J. Wysocki <rafael@kernel.org>
Subject: Re: [PATCH] ACPI: avoid NULL pointer arithmetic
Bob, this is ACPICA material.
Would it be possible to apply this to the upstream from the patch or do you need a PR for this?
On 9/27/2021 2:13 PM, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
>
> There are some very old macros for doing an open-coded offsetof() and
> cast between pointer and integer in ACPI headers. clang-14 now
> complains about these:
>
> drivers/acpi/acpica/tbfadt.c:86:3: error: performing pointer subtraction with a null pointer has undefined behavior [-Werror,-Wnull-pointer-subtraction]
> ACPI_FADT_OFFSET(pm_timer_block),
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> include/acpi/actbl.h:376:47: note: expanded from macro 'ACPI_FADT_OFFSET'
> #define ACPI_FADT_OFFSET(f) (u16) ACPI_OFFSET (struct acpi_table_fadt, f)
>
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> include/acpi/actypes.h:511:41: note: expanded from macro 'ACPI_OFFSET'
> #define ACPI_OFFSET(d, f) ACPI_PTR_DIFF (&(((d *) 0)->f), (void *) 0)
>
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> include/acpi/actypes.h:505:79: note: expanded from macro 'ACPI_PTR_DIFF'
> #define ACPI_PTR_DIFF(a, b) ((acpi_size) (ACPI_CAST_PTR (u8, (a)) - ACPI_CAST_PTR (u8, (b))))
>
> ^ ~~~~~~~~~~~~~~~~~~~~~~~ Convert them to the modern equivalents.
>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
> include/acpi/actypes.h | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/include/acpi/actypes.h b/include/acpi/actypes.h index
> 92c71dfce0d5..285bc7b73de3 100644
> --- a/include/acpi/actypes.h
> +++ b/include/acpi/actypes.h
> @@ -507,8 +507,8 @@ typedef u64 acpi_integer;
> /* Pointer/Integer type conversions */
>
> #define ACPI_TO_POINTER(i) ACPI_CAST_PTR (void, (acpi_size) (i))
> -#define ACPI_TO_INTEGER(p) ACPI_PTR_DIFF (p, (void *) 0)
> -#define ACPI_OFFSET(d, f) ACPI_PTR_DIFF (&(((d *) 0)->f), (void *) 0)
> +#define ACPI_TO_INTEGER(p) ((uintptr_t)(p))
> +#define ACPI_OFFSET(d, f) offsetof(d, f)
> #define ACPI_PHYSADDR_TO_PTR(i) ACPI_TO_POINTER(i)
> #define ACPI_PTR_TO_PHYSADDR(i) ACPI_TO_INTEGER(i)
>
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] ACPI: avoid NULL pointer arithmetic
2021-09-28 20:39 ` Moore, Robert
@ 2021-09-29 12:01 ` Rafael J. Wysocki
0 siblings, 0 replies; 7+ messages in thread
From: Rafael J. Wysocki @ 2021-09-29 12:01 UTC (permalink / raw)
To: Moore, Robert
Cc: Wysocki, Rafael J, Arnd Bergmann, Arnd Bergmann,
Nathan Chancellor, Nick Desaulniers, linux-acpi, devel,
linux-kernel, llvm, Len Brown, Rafael J. Wysocki
On Tue, Sep 28, 2021 at 10:39 PM Moore, Robert <robert.moore@intel.com> wrote:
>
> I can take this patch as-is, I think. I'll try for the next acpica release later this week.
Thanks!
> -----Original Message-----
> From: Wysocki, Rafael J <rafael.j.wysocki@intel.com>
> Sent: Tuesday, September 28, 2021 10:44 AM
> To: Arnd Bergmann <arnd@kernel.org>; Moore, Robert <robert.moore@intel.com>
> Cc: Arnd Bergmann <arnd@arndb.de>; Nathan Chancellor <nathan@kernel.org>; Nick Desaulniers <ndesaulniers@google.com>; Erik Kaneda <erik.kaneda@intel.com>; linux-acpi@vger.kernel.org; devel@acpica.org; linux-kernel@vger.kernel.org; llvm@lists.linux.dev; Len Brown <lenb@kernel.org>; Rafael J. Wysocki <rafael@kernel.org>
> Subject: Re: [PATCH] ACPI: avoid NULL pointer arithmetic
>
> Bob, this is ACPICA material.
>
> Would it be possible to apply this to the upstream from the patch or do you need a PR for this?
>
> On 9/27/2021 2:13 PM, Arnd Bergmann wrote:
> > From: Arnd Bergmann <arnd@arndb.de>
> >
> > There are some very old macros for doing an open-coded offsetof() and
> > cast between pointer and integer in ACPI headers. clang-14 now
> > complains about these:
> >
> > drivers/acpi/acpica/tbfadt.c:86:3: error: performing pointer subtraction with a null pointer has undefined behavior [-Werror,-Wnull-pointer-subtraction]
> > ACPI_FADT_OFFSET(pm_timer_block),
> > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > include/acpi/actbl.h:376:47: note: expanded from macro 'ACPI_FADT_OFFSET'
> > #define ACPI_FADT_OFFSET(f) (u16) ACPI_OFFSET (struct acpi_table_fadt, f)
> >
> > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > include/acpi/actypes.h:511:41: note: expanded from macro 'ACPI_OFFSET'
> > #define ACPI_OFFSET(d, f) ACPI_PTR_DIFF (&(((d *) 0)->f), (void *) 0)
> >
> > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > include/acpi/actypes.h:505:79: note: expanded from macro 'ACPI_PTR_DIFF'
> > #define ACPI_PTR_DIFF(a, b) ((acpi_size) (ACPI_CAST_PTR (u8, (a)) - ACPI_CAST_PTR (u8, (b))))
> >
> > ^ ~~~~~~~~~~~~~~~~~~~~~~~ Convert them to the modern equivalents.
> >
> > Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> > ---
> > include/acpi/actypes.h | 4 ++--
> > 1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/include/acpi/actypes.h b/include/acpi/actypes.h index
> > 92c71dfce0d5..285bc7b73de3 100644
> > --- a/include/acpi/actypes.h
> > +++ b/include/acpi/actypes.h
> > @@ -507,8 +507,8 @@ typedef u64 acpi_integer;
> > /* Pointer/Integer type conversions */
> >
> > #define ACPI_TO_POINTER(i) ACPI_CAST_PTR (void, (acpi_size) (i))
> > -#define ACPI_TO_INTEGER(p) ACPI_PTR_DIFF (p, (void *) 0)
> > -#define ACPI_OFFSET(d, f) ACPI_PTR_DIFF (&(((d *) 0)->f), (void *) 0)
> > +#define ACPI_TO_INTEGER(p) ((uintptr_t)(p))
> > +#define ACPI_OFFSET(d, f) offsetof(d, f)
> > #define ACPI_PHYSADDR_TO_PTR(i) ACPI_TO_POINTER(i)
> > #define ACPI_PTR_TO_PHYSADDR(i) ACPI_TO_INTEGER(i)
> >
>
>
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] ACPI: avoid NULL pointer arithmetic
2021-09-27 12:13 [PATCH] ACPI: avoid NULL pointer arithmetic Arnd Bergmann
2021-09-28 17:43 ` Rafael J. Wysocki
@ 2021-09-29 18:47 ` Rafael J. Wysocki
2021-09-30 18:52 ` Rafael J. Wysocki
1 sibling, 1 reply; 7+ messages in thread
From: Rafael J. Wysocki @ 2021-09-29 18:47 UTC (permalink / raw)
To: Arnd Bergmann
Cc: Rafael J. Wysocki, Len Brown, Robert Moore, Arnd Bergmann,
Rafael J. Wysocki, Nathan Chancellor, Nick Desaulniers,
Erik Kaneda, ACPI Devel Maling List,
open list:ACPI COMPONENT ARCHITECTURE (ACPICA),
Linux Kernel Mailing List, llvm
On Mon, Sep 27, 2021 at 2:13 PM Arnd Bergmann <arnd@kernel.org> wrote:
>
> From: Arnd Bergmann <arnd@arndb.de>
>
> There are some very old macros for doing an open-coded offsetof() and
> cast between pointer and integer in ACPI headers. clang-14 now complains
> about these:
>
> drivers/acpi/acpica/tbfadt.c:86:3: error: performing pointer subtraction with a null pointer has undefined behavior [-Werror,-Wnull-pointer-subtraction]
> ACPI_FADT_OFFSET(pm_timer_block),
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> include/acpi/actbl.h:376:47: note: expanded from macro 'ACPI_FADT_OFFSET'
> #define ACPI_FADT_OFFSET(f) (u16) ACPI_OFFSET (struct acpi_table_fadt, f)
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> include/acpi/actypes.h:511:41: note: expanded from macro 'ACPI_OFFSET'
> #define ACPI_OFFSET(d, f) ACPI_PTR_DIFF (&(((d *) 0)->f), (void *) 0)
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> include/acpi/actypes.h:505:79: note: expanded from macro 'ACPI_PTR_DIFF'
> #define ACPI_PTR_DIFF(a, b) ((acpi_size) (ACPI_CAST_PTR (u8, (a)) - ACPI_CAST_PTR (u8, (b))))
> ^ ~~~~~~~~~~~~~~~~~~~~~~~
> Convert them to the modern equivalents.
>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
> include/acpi/actypes.h | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/include/acpi/actypes.h b/include/acpi/actypes.h
> index 92c71dfce0d5..285bc7b73de3 100644
> --- a/include/acpi/actypes.h
> +++ b/include/acpi/actypes.h
> @@ -507,8 +507,8 @@ typedef u64 acpi_integer;
> /* Pointer/Integer type conversions */
>
> #define ACPI_TO_POINTER(i) ACPI_CAST_PTR (void, (acpi_size) (i))
> -#define ACPI_TO_INTEGER(p) ACPI_PTR_DIFF (p, (void *) 0)
> -#define ACPI_OFFSET(d, f) ACPI_PTR_DIFF (&(((d *) 0)->f), (void *) 0)
> +#define ACPI_TO_INTEGER(p) ((uintptr_t)(p))
> +#define ACPI_OFFSET(d, f) offsetof(d, f)
> #define ACPI_PHYSADDR_TO_PTR(i) ACPI_TO_POINTER(i)
> #define ACPI_PTR_TO_PHYSADDR(i) ACPI_TO_INTEGER(i)
>
> --
Queued up as 5.16 material, converted into an upstream ACPICA pull
request and submitted, thanks!
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] ACPI: avoid NULL pointer arithmetic
2021-09-29 18:47 ` Rafael J. Wysocki
@ 2021-09-30 18:52 ` Rafael J. Wysocki
2021-09-30 20:36 ` Arnd Bergmann
0 siblings, 1 reply; 7+ messages in thread
From: Rafael J. Wysocki @ 2021-09-30 18:52 UTC (permalink / raw)
To: Arnd Bergmann
Cc: Len Brown, Robert Moore, Arnd Bergmann, Rafael J. Wysocki,
Nathan Chancellor, Nick Desaulniers, Erik Kaneda,
ACPI Devel Maling List,
open list:ACPI COMPONENT ARCHITECTURE (ACPICA),
Linux Kernel Mailing List, llvm
On Wed, Sep 29, 2021 at 8:47 PM Rafael J. Wysocki <rafael@kernel.org> wrote:
>
> On Mon, Sep 27, 2021 at 2:13 PM Arnd Bergmann <arnd@kernel.org> wrote:
> >
> > From: Arnd Bergmann <arnd@arndb.de>
> >
> > There are some very old macros for doing an open-coded offsetof() and
> > cast between pointer and integer in ACPI headers. clang-14 now complains
> > about these:
> >
> > drivers/acpi/acpica/tbfadt.c:86:3: error: performing pointer subtraction with a null pointer has undefined behavior [-Werror,-Wnull-pointer-subtraction]
> > ACPI_FADT_OFFSET(pm_timer_block),
> > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > include/acpi/actbl.h:376:47: note: expanded from macro 'ACPI_FADT_OFFSET'
> > #define ACPI_FADT_OFFSET(f) (u16) ACPI_OFFSET (struct acpi_table_fadt, f)
> > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > include/acpi/actypes.h:511:41: note: expanded from macro 'ACPI_OFFSET'
> > #define ACPI_OFFSET(d, f) ACPI_PTR_DIFF (&(((d *) 0)->f), (void *) 0)
> > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > include/acpi/actypes.h:505:79: note: expanded from macro 'ACPI_PTR_DIFF'
> > #define ACPI_PTR_DIFF(a, b) ((acpi_size) (ACPI_CAST_PTR (u8, (a)) - ACPI_CAST_PTR (u8, (b))))
> > ^ ~~~~~~~~~~~~~~~~~~~~~~~
> > Convert them to the modern equivalents.
> >
> > Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> > ---
> > include/acpi/actypes.h | 4 ++--
> > 1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/include/acpi/actypes.h b/include/acpi/actypes.h
> > index 92c71dfce0d5..285bc7b73de3 100644
> > --- a/include/acpi/actypes.h
> > +++ b/include/acpi/actypes.h
> > @@ -507,8 +507,8 @@ typedef u64 acpi_integer;
> > /* Pointer/Integer type conversions */
> >
> > #define ACPI_TO_POINTER(i) ACPI_CAST_PTR (void, (acpi_size) (i))
> > -#define ACPI_TO_INTEGER(p) ACPI_PTR_DIFF (p, (void *) 0)
> > -#define ACPI_OFFSET(d, f) ACPI_PTR_DIFF (&(((d *) 0)->f), (void *) 0)
> > +#define ACPI_TO_INTEGER(p) ((uintptr_t)(p))
> > +#define ACPI_OFFSET(d, f) offsetof(d, f)
> > #define ACPI_PHYSADDR_TO_PTR(i) ACPI_TO_POINTER(i)
> > #define ACPI_PTR_TO_PHYSADDR(i) ACPI_TO_INTEGER(i)
> >
> > --
>
> Queued up as 5.16 material, converted into an upstream ACPICA pull
> request and submitted, thanks!
And reverted from there, because it introduced build issues.
Can we use alternative definitions that don't depend on uintptr_t and
offsetof()?
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] ACPI: avoid NULL pointer arithmetic
2021-09-30 18:52 ` Rafael J. Wysocki
@ 2021-09-30 20:36 ` Arnd Bergmann
0 siblings, 0 replies; 7+ messages in thread
From: Arnd Bergmann @ 2021-09-30 20:36 UTC (permalink / raw)
To: Rafael J. Wysocki
Cc: Len Brown, Robert Moore, Arnd Bergmann, Rafael J. Wysocki,
Nathan Chancellor, Nick Desaulniers, Erik Kaneda,
ACPI Devel Maling List,
open list:ACPI COMPONENT ARCHITECTURE (ACPICA),
Linux Kernel Mailing List, llvm
On Thu, Sep 30, 2021 at 8:52 PM Rafael J. Wysocki <rafael@kernel.org> wrote:
>
> On Wed, Sep 29, 2021 at 8:47 PM Rafael J. Wysocki <rafael@kernel.org> wrote:
> >
> > On Mon, Sep 27, 2021 at 2:13 PM Arnd Bergmann <arnd@kernel.org> wrote:
> > >
> > > #define ACPI_TO_POINTER(i) ACPI_CAST_PTR (void, (acpi_size) (i))
> > > -#define ACPI_TO_INTEGER(p) ACPI_PTR_DIFF (p, (void *) 0)
> > > -#define ACPI_OFFSET(d, f) ACPI_PTR_DIFF (&(((d *) 0)->f), (void *) 0)
> > > +#define ACPI_TO_INTEGER(p) ((uintptr_t)(p))
> > > +#define ACPI_OFFSET(d, f) offsetof(d, f)
> > > #define ACPI_PHYSADDR_TO_PTR(i) ACPI_TO_POINTER(i)
> > > #define ACPI_PTR_TO_PHYSADDR(i) ACPI_TO_INTEGER(i)
> > >
> > > --
> >
> > Queued up as 5.16 material, converted into an upstream ACPICA pull
> > request and submitted, thanks!
>
> And reverted from there, because it introduced build issues.
>
> Can we use alternative definitions that don't depend on uintptr_t and
> offsetof()?
It's a bit tricky, as both were introduced to avoid portability issues.
For uintptr_t, we could use 'unsigned long', which works on everything
that Linux can run on, but wouldn't work if this code can be compiled
for 64-bit Windows. 'size_t' probably works, but likely has the same problem
as 'uintptr_t' because they require and additional #include. I see
that some code uses acpi_uintptr_t, which looks like it is meant to
replace uintptr_t, this is defined as 'void *' in include/acpi/actypes.h,
so that probably wouldn't avoid the warning.
For offsetof(), we could use __builtin_offsetof(), which would work with
any gcc-compatible compiler, if the goal is to avoid including <stddef.h>.
If it has to work on other compilers, there is no portable way that doesn't
rely on standard headers. The best idea I'd have would be to use
"#ifdef offsetof" to choose between the trivial implementation I had
and the old one that works for non-standard C but may invoke
undefined behavior.
Arnd
^ permalink raw reply [flat|nested] 7+ messages in thread
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2021-09-27 12:13 [PATCH] ACPI: avoid NULL pointer arithmetic Arnd Bergmann
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2021-09-28 20:39 ` Moore, Robert
2021-09-29 12:01 ` Rafael J. Wysocki
2021-09-29 18:47 ` Rafael J. Wysocki
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