[PATCH -v2 3/4] ACPI APEI: Convert atomicio routines

Myron Stowe
2011-11-07T23:23:41Z

APEI needs memory access in interrupt context. The obvious choice is
acpi_read(), but originally it couldn't be used in interrupt context
because it makes temporary mappings with ioremap(). Therefore, we added
drivers/acpi/atomicio.c, which provides:
acpi_pre_map_gar() -- ioremap in process context
acpi_atomic_read() -- memory access in interrupt context
acpi_post_unmap_gar() -- iounmap

Later we added acpi_os_map_generic_address() (2971852) and enhanced
acpi_read() so it works in interrupt context as long as the address has
been previously mapped (620242a). Now this sequence:
acpi_os_map_generic_address() -- ioremap in process context
acpi_read()/apei_read() -- now OK in interrupt context
acpi_os_unmap_generic_address()
is equivalent to what atomicio.c provides.

This patch introduces apei_read() and apei_write(), which currently are
functional equivalents of acpi_read() and acpi_write(). This is mainly
proactive, to prevent APEI breakages if acpi_read() and acpi_write()
are ever augmented to support the 'bit_offset' field of GAS, as APEI's
__apei_exec_write_register() precludes splitting up functionality
related to 'bit_offset' and APEI's 'mask' (see its
APEI_EXEC_PRESERVE_REGISTER block).

With apei_read() and apei_write() in place, usages of atomicio routines
are converted to apei_read()/apei_write() and existing calls within
osl.c and the CA, based on the re-factoring that was done in an earlier
patch series - http://marc.info/?l=linux-acpi&m=128769263327206&w=2:
acpi_pre_map_gar() --> acpi_os_map_generic_address()
acpi_post_unmap_gar() --> acpi_os_unmap_generic_address()
acpi_atomic_read() --> apei_read()
acpi_atomic_write() --> apei_write()

Note that acpi_read() and acpi_write() currently use 'bit_width'
for accessing GARs which seems incorrect. 'bit_width' is the size of
the register, while 'access_width' is the size of the access the
processor must generate on the bus. The 'access_width' may be larger,
for example, if the hardware only supports 32-bit or 64-bit reads. I
wanted to minimize any possible impacts with this patch series so I
did *not* change this behavior.

Signed-off-by: Myron Stowe <myron.stowe@redhat.com>
---

drivers/acpi/apei/apei-base.c | 102 +++++++++++++++++++++++++++++++++++--
drivers/acpi/apei/apei-internal.h | 3 +
drivers/acpi/apei/ghes.c | 10 ++--
3 files changed, 104 insertions(+), 11 deletions(-)

diff --git a/drivers/acpi/apei/apei-base.c b/drivers/acpi/apei/apei-base.c
index 6154036..f54550a 100644
--- a/drivers/acpi/apei/apei-base.c
+++ b/drivers/acpi/apei/apei-base.c
@@ -34,13 +34,13 @@
#include <linux/module.h>
#include <linux/init.h>
#include <linux/acpi.h>
+#include <linux/acpi_io.h>
#include <linux/slab.h>
#include <linux/io.h>
#include <linux/kref.h>
#include <linux/rculist.h>
#include <linux/interrupt.h>
#include <linux/debugfs.h>
-#include <acpi/atomicio.h>

#include "apei-internal.h"

@@ -70,7 +70,7 @@ int __apei_exec_read_register(struct acpi_whea_header *entry, u64 *val)
{
int rc;

- rc = acpi_atomic_read(val, &entry->register_region);
+ rc = apei_read(val, &entry->register_region);
if (rc)
return rc;
*val >>= entry->register_region.bit_offset;
@@ -116,13 +116,13 @@ int __apei_exec_write_register(struct acpi_whea_header *entry, u64 val)
val <<= entry->register_region.bit_offset;
if (entry->flags & APEI_EXEC_PRESERVE_REGISTER) {
u64 valr = 0;
- rc = acpi_atomic_read(&valr, &entry->register_region);
+ rc = apei_read(&valr, &entry->register_region);
if (rc)
return rc;
valr &= ~(entry->mask << entry->register_region.bit_offset);
val |= valr;
}
- rc = acpi_atomic_write(val, &entry->register_region);
+ rc = apei_write(val, &entry->register_region);

return rc;
}
@@ -243,7 +243,7 @@ static int pre_map_gar_callback(struct apei_exec_context *ctx,
u8 ins = entry->instruction;

if (ctx->ins_table[ins].flags & APEI_EXEC_INS_ACCESS_REGISTER)
- return acpi_pre_map_gar(&entry->register_region);
+ return acpi_os_map_generic_address(&entry->register_region);

return 0;
}
@@ -276,7 +276,7 @@ static int post_unmap_gar_callback(struct apei_exec_context *ctx,
u8 ins = entry->instruction;

if (ctx->ins_table[ins].flags & APEI_EXEC_INS_ACCESS_REGISTER)
- acpi_post_unmap_gar(&entry->register_region);
+ acpi_os_unmap_generic_address(&entry->register_region);

return 0;
}
@@ -553,6 +553,96 @@ static int apei_check_gar(struct acpi_generic_address *reg, u64 *paddr)
return 0;
}

+/* read GAR in interrupt (including NMI) or process context */
+int apei_read(u64 *val, struct acpi_generic_address *reg)
+{
+ int rc;
+ u64 address;
+ u32 tmp, width = reg->bit_width;
+ acpi_status status;
+
+ rc = apei_check_gar(reg, &address);
+ if (rc)
+ return rc;
+
+ if (width == 64)
+ width = 32; /* Break into two 32-bit transfers */
+
+ *val = 0;
+ switch(reg->space_id) {
+ case ACPI_ADR_SPACE_SYSTEM_MEMORY:
+ status = acpi_os_read_memory((acpi_physical_address)
+ address, &tmp, width);
+ if (ACPI_FAILURE(status))
+ return -EIO;
+ *val = tmp;
+
+ if (reg->bit_width == 64) {
+ /* Read the top 32 bits */
+ status = acpi_os_read_memory((acpi_physical_address)
+ (address + 4), &tmp, 32);
+ if (ACPI_FAILURE(status))
+ return -EIO;
+ *val |= ((u64)tmp << 32);
+ }
+ break;
+ case ACPI_ADR_SPACE_SYSTEM_IO:
+ status = acpi_os_read_port(address, (u32 *)val, reg->bit_width);
+ if (ACPI_FAILURE(status))
+ return -EIO;
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(apei_read);
+
+/* write GAR in interrupt (including NMI) or process context */
+int apei_write(u64 val, struct acpi_generic_address *reg)
+{
+ int rc;
+ u64 address;
+ u32 width = reg->bit_width;
+ acpi_status status;
+
+ rc = apei_check_gar(reg, &address);
+ if (rc)
+ return rc;
+
+ if (width == 64)
+ width = 32; /* Break into two 32-bit transfers */
+
+ switch (reg->space_id) {
+ case ACPI_ADR_SPACE_SYSTEM_MEMORY:
+ status = acpi_os_write_memory((acpi_physical_address)
+ address, ACPI_LODWORD(val),
+ width);
+ if (ACPI_FAILURE(status))
+ return -EIO;
+
+ if (reg->bit_width == 64) {
+ status = acpi_os_write_memory((acpi_physical_address)
+ (address + 4),
+ ACPI_HIDWORD(val), 32);
+ if (ACPI_FAILURE(status))
+ return -EIO;
+ }
+ break;
+ case ACPI_ADR_SPACE_SYSTEM_IO:
+ status = acpi_os_write_port(address, val, reg->bit_width);
+ if (ACPI_FAILURE(status))
+ return -EIO;
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(apei_write);
+
static int collect_res_callback(struct apei_exec_context *ctx,
struct acpi_whea_header *entry,
void *data)
diff --git a/drivers/acpi/apei/apei-internal.h b/drivers/acpi/apei/apei-internal.h
index f57050e..617fb10 100644
--- a/drivers/acpi/apei/apei-internal.h
+++ b/drivers/acpi/apei/apei-internal.h
@@ -68,6 +68,9 @@ static inline int apei_exec_run_optional(struct apei_exec_context *ctx, u8 actio
/* IP has been set in instruction function */
#define APEI_EXEC_SET_IP 1

+int apei_read(u64 *val, struct acpi_generic_address *reg);
+int apei_write(u64 val, struct acpi_generic_address *reg);
+
int __apei_exec_read_register(struct acpi_whea_header *entry, u64 *val);
int __apei_exec_write_register(struct acpi_whea_header *entry, u64 val);
int apei_exec_read_register(struct apei_exec_context *ctx,
diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
index b8e08cb..9d75fbc 100644
--- a/drivers/acpi/apei/ghes.c
+++ b/drivers/acpi/apei/ghes.c
@@ -33,6 +33,7 @@
#include <linux/module.h>
#include <linux/init.h>
#include <linux/acpi.h>
+#include <linux/acpi_io.h>
#include <linux/io.h>
#include <linux/interrupt.h>
#include <linux/timer.h>
@@ -46,7 +47,6 @@
#include <linux/llist.h>
#include <linux/genalloc.h>
#include <acpi/apei.h>
-#include <acpi/atomicio.h>
#include <acpi/hed.h>
#include <asm/mce.h>
#include <asm/tlbflush.h>
@@ -299,7 +299,7 @@ static struct ghes *ghes_new(struct acpi_hest_generic *generic)
if (!ghes)
return ERR_PTR(-ENOMEM);
ghes->generic = generic;
- rc = acpi_pre_map_gar(&generic->error_status_address);
+ rc = acpi_os_map_generic_address(&generic->error_status_address);
if (rc)
goto err_free;
error_block_length = generic->error_block_length;
@@ -319,7 +319,7 @@ static struct ghes *ghes_new(struct acpi_hest_generic *generic)
return ghes;

err_unmap:
- acpi_post_unmap_gar(&generic->error_status_address);
+ acpi_os_unmap_generic_address(&generic->error_status_address);
err_free:
kfree(ghes);
return ERR_PTR(rc);
@@ -328,7 +328,7 @@ err_free:
static void ghes_fini(struct ghes *ghes)
{
kfree(ghes->estatus);
- acpi_post_unmap_gar(&ghes->generic->error_status_address);
+ acpi_os_unmap_generic_address(&ghes->generic->error_status_address);
}

enum {
@@ -399,7 +399,7 @@ static int ghes_read_estatus(struct ghes *ghes, int silent)
u32 len;
int rc;

- rc = acpi_atomic_read(&buf_paddr, &g->error_status_address);
+ rc = apei_read(&buf_paddr, &g->error_status_address);
if (rc) {
if (!silent && printk_ratelimit())
pr_warning(FW_WARN GHES_PFX