From: Andrew Donnellan <ajd@linux.ibm.com>
To: nathanl@linux.ibm.com, Michael Ellerman <mpe@ellerman.id.au>,
Nicholas Piggin <npiggin@gmail.com>,
Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Tyrel Datwyler <tyreld@linux.ibm.com>,
Scott Cheloha <cheloha@linux.ibm.com>,
Laurent Dufour <ldufour@linux.ibm.com>,
linuxppc-dev@lists.ozlabs.org, Nick Child <nnac123@linux.ibm.com>
Subject: Re: [PATCH 1/8] powerpc/rtas: ensure 8-byte alignment for struct rtas_args
Date: Thu, 23 Mar 2023 15:00:09 +1100 [thread overview]
Message-ID: <67a5240df616de97f526049ef2aad8493cc3ab38.camel@linux.ibm.com> (raw)
In-Reply-To: <20230220-rtas-queue-for-6-4-v1-1-010e4416f13f@linux.ibm.com>
On Mon, 2023-03-06 at 15:33 -0600, Nathan Lynch via B4 Relay wrote:
> > From: Nathan Lynch <nathanl@linux.ibm.com>
> >
> > CHRP and PAPR agree: "In order to make an RTAS call, the operating
> > system must construct an argument call buffer aligned on an eight
> > byte
> > boundary in physically contiguous real memory [...]." (7.2.7
> > Calling
> > Mechanism and Conventions).
> >
> > struct rtas_args is the type used for this argument call buffer.
> > The
> > unarchitected 'rets' member happens to produce 8-byte alignment for
> > the struct on 64-bit targets in practice. But without an alignment
> > directive the structure will have only 4-byte alignment on 32-bit
> > targets:
> >
> > $ nm b/{before,after}/chrp32/vmlinux | grep rtas_args
> > c096881c b rtas_args
> > c0968820 b rtas_args
> >
> > Add an alignment directive to the struct rtas_args declaration so
> > all
> > instances have the alignment required by the specs. rtas-types.h no
> > longer refers to any spinlock types, so drop the spinlock_types.h
> > inclusion while we're here.
> >
> > Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Reviewed-by: Andrew Donnellan <ajd@linux.ibm.com>
> > ---
> > arch/powerpc/include/asm/rtas-types.h | 5 +++--
> > 1 file changed, 3 insertions(+), 2 deletions(-)
> >
> > diff --git a/arch/powerpc/include/asm/rtas-types.h
> > b/arch/powerpc/include/asm/rtas-types.h
> > index f2ad4a96cbc5..861145c8a021 100644
> > --- a/arch/powerpc/include/asm/rtas-types.h
> > +++ b/arch/powerpc/include/asm/rtas-types.h
> > @@ -2,7 +2,8 @@
> > #ifndef _ASM_POWERPC_RTAS_TYPES_H
> > #define _ASM_POWERPC_RTAS_TYPES_H
> >
> > -#include <linux/spinlock_types.h>
> > +#include <linux/compiler_attributes.h>
> > +#include <linux/sizes.h>
> >
> > typedef __be32 rtas_arg_t;
> >
> > @@ -12,7 +13,7 @@ struct rtas_args {
> > __be32 nret;
> > rtas_arg_t args[16];
> > rtas_arg_t *rets; /* Pointer to return values in
> > args[].
> > */
> > -};
> > +} __aligned(SZ_8);
Nowhere else in the kernel uses __aligned(SZ_8) over just __aligned(8),
which I suppose would also save an include, but I don't care either
way.
> >
> > struct rtas_t {
> > unsigned long entry; /* physical address pointer
> > */
> >
--
Andrew Donnellan OzLabs, ADL Canberra
ajd@linux.ibm.com IBM Australia Limited
next prev parent reply other threads:[~2023-03-23 4:01 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-06 21:33 [PATCH 0/8] RTAS changes for 6.4 Nathan Lynch via B4 Relay
2023-03-06 21:33 ` Nathan Lynch
2023-03-06 21:33 ` [PATCH 1/8] powerpc/rtas: ensure 8-byte alignment for struct rtas_args Nathan Lynch
2023-03-06 21:33 ` Nathan Lynch via B4 Relay
2023-03-23 4:00 ` Andrew Donnellan [this message]
2023-03-06 21:33 ` [PATCH 2/8] powerpc/rtas: use memmove for potentially overlapping buffer copy Nathan Lynch
2023-03-06 21:33 ` Nathan Lynch via B4 Relay
2023-03-23 4:09 ` Andrew Donnellan
2023-03-06 21:33 ` [PATCH 3/8] powerpc/rtas: rtas_call_unlocked() kerneldoc Nathan Lynch via B4 Relay
2023-03-06 21:33 ` Nathan Lynch
2023-03-23 4:15 ` Andrew Donnellan
2023-03-06 21:33 ` [PATCH 4/8] powerpc/rtas: fix miswording in rtas_function kerneldoc Nathan Lynch via B4 Relay
2023-03-06 21:33 ` Nathan Lynch
2023-03-23 0:17 ` Andrew Donnellan
2023-03-06 21:33 ` [PATCH 5/8] powerpc/rtas: rename va_rtas_call_unlocked() to va_rtas_call() Nathan Lynch
2023-03-06 21:33 ` Nathan Lynch via B4 Relay
2023-03-23 4:17 ` Andrew Donnellan
2023-03-23 16:11 ` Nathan Lynch
2023-03-29 12:24 ` Michael Ellerman
2023-03-06 21:33 ` [PATCH 6/8] powerpc/rtas: lockdep annotations Nathan Lynch
2023-03-06 21:33 ` Nathan Lynch via B4 Relay
2023-03-23 6:01 ` Andrew Donnellan
2023-03-06 21:33 ` [PATCH 7/8] powerpc/rtas: warn on unsafe argument to rtas_call_unlocked() Nathan Lynch via B4 Relay
2023-03-06 21:33 ` Nathan Lynch
2023-03-23 4:25 ` Andrew Donnellan
2023-03-23 12:17 ` Nathan Lynch
2023-03-24 0:56 ` Nathan Lynch
2023-03-29 12:20 ` Michael Ellerman
2023-03-29 16:23 ` Nathan Lynch
2023-03-06 21:33 ` [PATCH 8/8] powerpc/rtas: consume retry statuses in sys_rtas() Nathan Lynch via B4 Relay
2023-03-06 21:33 ` Nathan Lynch
2023-03-23 6:26 ` Andrew Donnellan
2023-03-23 19:39 ` Nathan Lynch
2023-03-23 9:44 ` Michael Ellerman
2023-03-23 13:40 ` Nathan Lynch
2024-01-25 15:55 ` Christophe Leroy
2024-01-25 16:33 ` Nathan Lynch
2024-01-25 16:46 ` Christophe Leroy
2024-01-25 17:23 ` Nathan Lynch
2023-04-06 1:09 ` (subset) [PATCH 0/8] RTAS changes for 6.4 Michael Ellerman
2023-04-26 12:12 ` Michael Ellerman
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