| Message ID | 20181203180613.228133-21-james.morse@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | APEI in_nmi() rework and SDEI wire-up | expand |
On Mon, Dec 03, 2018 at 06:06:08PM +0000, James Morse wrote: > Now that ghes notification helpers provide the fixmap slots and > take the lock themselves, multiple NMI-like notifications can > be used on arm64. > > These should be named after their notification method as they can't > all be called 'NMI'. x86's NOTIFY_NMI already is, change the SEA > fixmap entry to be called FIX_APEI_GHES_SEA. > > Future patches can add support for FIX_APEI_GHES_SEI and > FIX_APEI_GHES_SDEI_{NORMAL,CRITICAL}. > > Because all of ghes.c builds on both architectures, provide a > constant for each fixmap entry that the architecture will never > use. > > Signed-off-by: James Morse <james.morse@arm.com> > > --- > Changes since v6: > * Added #ifdef definitions of each missing fixmap entry. > > Changes since v3: > * idx/lock are now in a separate struct. > * Add to the comment above ghes_fixmap_lock_irq so that it makes more > sense in isolation. > > fixup for split fixmap > --- > arch/arm64/include/asm/fixmap.h | 2 +- > drivers/acpi/apei/ghes.c | 10 +++++++++- > 2 files changed, 10 insertions(+), 2 deletions(-) > > diff --git a/arch/arm64/include/asm/fixmap.h b/arch/arm64/include/asm/fixmap.h > index ec1e6d6fa14c..966dd4bb23f2 100644 > --- a/arch/arm64/include/asm/fixmap.h > +++ b/arch/arm64/include/asm/fixmap.h > @@ -55,7 +55,7 @@ enum fixed_addresses { > #ifdef CONFIG_ACPI_APEI_GHES > /* Used for GHES mapping from assorted contexts */ > FIX_APEI_GHES_IRQ, > - FIX_APEI_GHES_NMI, > + FIX_APEI_GHES_SEA, > #endif /* CONFIG_ACPI_APEI_GHES */ > > #ifdef CONFIG_UNMAP_KERNEL_AT_EL0 > diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c > index 849da0d43a21..6cbf9471b2a2 100644 > --- a/drivers/acpi/apei/ghes.c > +++ b/drivers/acpi/apei/ghes.c > @@ -85,6 +85,14 @@ > ((struct acpi_hest_generic_status *) \ > ((struct ghes_estatus_node *)(estatus_node) + 1)) > > +/* NMI-like notifications vary by architecture. Fill in the fixmap gaps */ > +#ifndef CONFIG_HAVE_ACPI_APEI_NMI > +#define FIX_APEI_GHES_NMI -1 > +#endif > +#ifndef CONFIG_ACPI_APEI_SEA > +#define FIX_APEI_GHES_SEA -1 I'm guessing those -1 are going to cause __set_fixmap() to fail, right? I'm wondering if we could catch that situation in ghes_map() already to protect ourselves against future changes in the fixmap code...
Hi Boris, On 21/01/2019 17:27, Borislav Petkov wrote: > On Mon, Dec 03, 2018 at 06:06:08PM +0000, James Morse wrote: >> Now that ghes notification helpers provide the fixmap slots and >> take the lock themselves, multiple NMI-like notifications can >> be used on arm64. >> >> These should be named after their notification method as they can't >> all be called 'NMI'. x86's NOTIFY_NMI already is, change the SEA >> fixmap entry to be called FIX_APEI_GHES_SEA. >> >> Future patches can add support for FIX_APEI_GHES_SEI and >> FIX_APEI_GHES_SDEI_{NORMAL,CRITICAL}. >> >> Because all of ghes.c builds on both architectures, provide a >> constant for each fixmap entry that the architecture will never >> use. >> diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c >> index 849da0d43a21..6cbf9471b2a2 100644 >> --- a/drivers/acpi/apei/ghes.c >> +++ b/drivers/acpi/apei/ghes.c >> @@ -85,6 +85,14 @@ >> ((struct acpi_hest_generic_status *) \ >> ((struct ghes_estatus_node *)(estatus_node) + 1)) >> >> +/* NMI-like notifications vary by architecture. Fill in the fixmap gaps */ >> +#ifndef CONFIG_HAVE_ACPI_APEI_NMI >> +#define FIX_APEI_GHES_NMI -1 >> +#endif >> +#ifndef CONFIG_ACPI_APEI_SEA >> +#define FIX_APEI_GHES_SEA -1 > > I'm guessing those -1 are going to cause __set_fixmap() to fail, right? It shouldn't be possible, these are just to give the compiler something int shaped to work with, until it prunes all the callers. But for arm64, yes if would fail. -1 shouldn't alias an existing entry, and it will get caught by: | BUG_ON(idx <= FIX_HOLE || idx >= __end_of_fixed_addresses); I wanted BUILD_BUG_ON() here, as any user of these should be optimised out, but the compiler choked on that. __end_of_fixed_addresses would be a better arch-agnostic invalid value. It has to be defined as the last value in the enum for core code's fix_to_virt() to work. These two look like something left behind from when we had different #ifdeffery. The users of these two are now behind arch specific #ifdefs that since patch 12 of this series, can't be turned off, so I can remove these. We do need them for SDEI, as it is relying on IS_ENABLED() and the compiler's dead code elimination. But the compiler wants that symbol to have the right type before it gets that far. |#define FIX_APEI_GHES_SDEI_NORMAL (BUILD_BUG(), -1) Was the best I had, but this trips the BUILD_BUG() too early. With it, x86 BUILD_BUG()s. With just the -1 the path gets pruned out, and there are no 'sdei' symbols in the object file. ...at this point, I stopped caring! > I'm wondering if we could catch that situation in ghes_map() already to > protect ourselves against future changes in the fixmap code... We already skip registering notifiers if the kconfig option wasn't selected. We can't catch this at compile time, as the dead-code elimination seems to happen in multiple passes. I'll switch the SDEI ones to __end_of_fixed_addresses, as both architectures BUG() when they see this. Thanks, James
On Wed, Jan 23, 2019 at 06:33:02PM +0000, James Morse wrote: > Was the best I had, but this trips the BUILD_BUG() too early. > With it, x86 BUILD_BUG()s. With just the -1 the path gets pruned out, and there > are no 'sdei' symbols in the object file. > > ...at this point, I stopped caring! Yah, you said it: __end_of_fixed_addresses will practically give you the BUG behavior: if (idx >= __end_of_fixed_addresses) { BUG(); return; } and ARM64 does the same. > We already skip registering notifiers if the kconfig option wasn't selected. > > We can't catch this at compile time, as the dead-code elimination seems to > happen in multiple passes. > > I'll switch the SDEI ones to __end_of_fixed_addresses, as both architectures > BUG() when they see this. Right. Thx.
diff --git a/arch/arm64/include/asm/fixmap.h b/arch/arm64/include/asm/fixmap.h index ec1e6d6fa14c..966dd4bb23f2 100644 --- a/arch/arm64/include/asm/fixmap.h +++ b/arch/arm64/include/asm/fixmap.h @@ -55,7 +55,7 @@ enum fixed_addresses { #ifdef CONFIG_ACPI_APEI_GHES /* Used for GHES mapping from assorted contexts */ FIX_APEI_GHES_IRQ, - FIX_APEI_GHES_NMI, + FIX_APEI_GHES_SEA, #endif /* CONFIG_ACPI_APEI_GHES */ #ifdef CONFIG_UNMAP_KERNEL_AT_EL0 diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c index 849da0d43a21..6cbf9471b2a2 100644 --- a/drivers/acpi/apei/ghes.c +++ b/drivers/acpi/apei/ghes.c @@ -85,6 +85,14 @@ ((struct acpi_hest_generic_status *) \ ((struct ghes_estatus_node *)(estatus_node) + 1)) +/* NMI-like notifications vary by architecture. Fill in the fixmap gaps */ +#ifndef CONFIG_HAVE_ACPI_APEI_NMI +#define FIX_APEI_GHES_NMI -1 +#endif +#ifndef CONFIG_ACPI_APEI_SEA +#define FIX_APEI_GHES_SEA -1 +#endif + static inline bool is_hest_type_generic_v2(struct ghes *ghes) { return ghes->generic->header.type == ACPI_HEST_TYPE_GENERIC_ERROR_V2; @@ -954,7 +962,7 @@ int ghes_notify_sea(void) int rv; raw_spin_lock(&ghes_notify_lock_sea); - rv = ghes_estatus_queue_notified(&ghes_sea, FIX_APEI_GHES_NMI); + rv = ghes_estatus_queue_notified(&ghes_sea, FIX_APEI_GHES_SEA); raw_spin_unlock(&ghes_notify_lock_sea); return rv;
Now that ghes notification helpers provide the fixmap slots and take the lock themselves, multiple NMI-like notifications can be used on arm64. These should be named after their notification method as they can't all be called 'NMI'. x86's NOTIFY_NMI already is, change the SEA fixmap entry to be called FIX_APEI_GHES_SEA. Future patches can add support for FIX_APEI_GHES_SEI and FIX_APEI_GHES_SDEI_{NORMAL,CRITICAL}. Because all of ghes.c builds on both architectures, provide a constant for each fixmap entry that the architecture will never use. Signed-off-by: James Morse <james.morse@arm.com> --- Changes since v6: * Added #ifdef definitions of each missing fixmap entry. Changes since v3: * idx/lock are now in a separate struct. * Add to the comment above ghes_fixmap_lock_irq so that it makes more sense in isolation. fixup for split fixmap --- arch/arm64/include/asm/fixmap.h | 2 +- drivers/acpi/apei/ghes.c | 10 +++++++++- 2 files changed, 10 insertions(+), 2 deletions(-)