Hello Narayana,
How about using the rtas_work_area_alloc() instead of allocating a new
dedicated buffer
for errinjct only?
Checkout Commit 43033bc62d34 ("powerpc/pseries: add RTAS work area
allocator") for
infrastructure to allocated working buffer.
Also checkout commit e27e14231eb5 ("powerpc/pseries/dlpar: use RTAS work
area API")
on how to use work area API.
- Sourabh Jain
On 21/07/26 09:08, Narayana Murty N wrote:
ibm,errinjct requires a caller-provided work buffer whose physical
address is passed to RTAS firmware.
A static C array such as:
char rtas_errinjct_buf[1024] __aligned(SZ_1K);
only guarantees alignment, not physical placement. If the array lands
above the RTAS-safe range (RTAS_INSTANTIATE_MAX, 1 GB) or above 4 GB,
RTAS receives a truncated or invalid address and the injection call
will fail silently or corrupt memory.
Instead, introduce rtas_errinjct_buf as a global unsigned long storing
the physical address allocated during rtas_initialize() using
memblock_phys_alloc_range() with the same rtas_region upper bound used
for rtas_rmo_buf. This matches the existing placement model for
RTAS-accessible buffers and guarantees the physical address fits in 32
bits.
Usage:
void *buf = __va(rtas_errinjct_buf); /* kernel VA to fill */
u32 buf_phys = lower_32_bits(rtas_errinjct_buf); /* PA for RTAS */
Always check upper_32_bits(rtas_errinjct_buf) == 0 before passing the
lower 32 bits to RTAS.
Add rtas_errinjct_mutex to serialise the complete open-session /
inject / close-session firmware call sequence. A mutex is required
because the sequence involves multiple rtas_call() invocations with
possible busy/extended-delay retries that may sleep.
Signed-off-by: Narayana Murty N <[email protected]>
---
arch/powerpc/include/asm/rtas.h | 26 ++++++++++++++++++++++++++
arch/powerpc/kernel/rtas.c | 17 +++++++++++++++++
2 files changed, 43 insertions(+)
diff --git a/arch/powerpc/include/asm/rtas.h b/arch/powerpc/include/asm/rtas.h
index d046bbd5017d..59e3c1296018 100644
--- a/arch/powerpc/include/asm/rtas.h
+++ b/arch/powerpc/include/asm/rtas.h
@@ -4,6 +4,7 @@
#ifdef __KERNEL__
#include <linux/mutex.h>
+#include <linux/sizes.h>
#include <linux/spinlock.h>
#include <asm/page.h>
#include <asm/rtas-types.h>
@@ -519,6 +520,31 @@ int rtas_get_error_log_max(void);
extern spinlock_t rtas_data_buf_lock;
extern char rtas_data_buf[RTAS_DATA_BUF_SIZE];
+/*
+ * RTAS error-injection work buffer.
+ *
+ * ibm,errinjct requires a caller-provided work buffer whose physical
+ * address is passed to firmware. A static C array only guarantees
+ * alignment, not physical placement; if it lands above the RTAS-safe
+ * range or above 4 GB, RTAS receives a truncated or bogus address.
+ *
+ * rtas_errinjct_buf stores the physical address allocated during
+ * rtas_initialize() using memblock_phys_alloc_range() with the same
+ * rtas_region upper bound used for rtas_rmo_buf, matching the existing
+ * placement model for RTAS-accessible buffers.
+ *
+ * Use __va(rtas_errinjct_buf) to obtain the kernel virtual address for
+ * filling the buffer, and lower_32_bits(rtas_errinjct_buf) to pass the
+ * physical address to RTAS (after checking upper_32_bits() == 0).
+ *
+ * rtas_errinjct_mutex must be held across the complete
+ * ibm,open-errinjct / ibm,errinjct / ibm,close-errinjct sequence.
+ */
+#define RTAS_ERRINJCT_BUF_SIZE SZ_1K
+
+extern unsigned long rtas_errinjct_buf;
+extern struct mutex rtas_errinjct_mutex;
+
/* RMO buffer reserved for user-space RTAS use */
extern unsigned long rtas_rmo_buf;
diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c
index 27d53f34494d..7883f973e8c9 100644
--- a/arch/powerpc/kernel/rtas.c
+++ b/arch/powerpc/kernel/rtas.c
@@ -769,6 +769,17 @@ EXPORT_SYMBOL_GPL(rtas_data_buf);
unsigned long rtas_rmo_buf;
+/*
+ * Physical address of the ibm,errinjct work buffer. Allocated during
+ * rtas_initialize() using memblock_phys_alloc_range() below rtas_region
+ * so the address fits in 32 bits and is safe to pass to RTAS firmware.
+ */
+unsigned long rtas_errinjct_buf;
+EXPORT_SYMBOL_GPL(rtas_errinjct_buf);
+
+DEFINE_MUTEX(rtas_errinjct_mutex);
+EXPORT_SYMBOL_GPL(rtas_errinjct_mutex);
+
/*
* If non-NULL, this gets called when the kernel terminates.
* This is done like this so rtas_flash can be a module.
@@ -2109,6 +2120,12 @@ void __init rtas_initialize(void)
panic("ERROR: RTAS: Failed to allocate %lx bytes below %pa\n",
PAGE_SIZE, &rtas_region);
+ rtas_errinjct_buf = memblock_phys_alloc_range(RTAS_ERRINJCT_BUF_SIZE,
+ SZ_1K, 0, rtas_region);
+ if (!rtas_errinjct_buf)
+ panic("ERROR: RTAS: Failed to allocate %lu bytes below %pa\n",
+ (unsigned long)RTAS_ERRINJCT_BUF_SIZE, &rtas_region);
+
rtas_work_area_reserve_arena(rtas_region);
}
