[PATCH v2] sparc: Replace one-element array with flexible array member

[Thorsten Blum <thorsten.blum@linux.dev>]

Replace the deprecated one-element array with a modern flexible array
member in the struct hvtramp_descr.

Additionally, 15 unnecessary bytes were allocated for hdesc, but instead
of fixing the parentheses in the open-coded version, use struct_size()
to calculate the correct number of bytes.

Link: https://github.com/KSPP/linux/issues/79
Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
---
Changes in v2:
- Fix the number of mappings after feedback from Gustavo A. R. Silva
- Link to v1: https://lore.kernel.org/r/20241111200155.164621-3-thorsten.blum@linux.dev/
---
 arch/sparc/include/asm/hvtramp.h | 2 +-
 arch/sparc/kernel/smp_64.c       | 4 +---
 2 files changed, 2 insertions(+), 4 deletions(-)

diff --git a/arch/sparc/include/asm/hvtramp.h b/arch/sparc/include/asm/hvtramp.h
index 688ea43af0f5..ce2453ea4f2b 100644
--- a/arch/sparc/include/asm/hvtramp.h
+++ b/arch/sparc/include/asm/hvtramp.h
@@ -17,7 +17,7 @@ struct hvtramp_descr {
 	__u64			fault_info_va;
 	__u64			fault_info_pa;
 	__u64			thread_reg;
-	struct hvtramp_mapping	maps[1];
+	struct hvtramp_mapping	maps[];
 };
 
 void hv_cpu_startup(unsigned long hvdescr_pa);
diff --git a/arch/sparc/kernel/smp_64.c b/arch/sparc/kernel/smp_64.c
index e40c395db202..24d980220bf1 100644
--- a/arch/sparc/kernel/smp_64.c
+++ b/arch/sparc/kernel/smp_64.c
@@ -297,9 +297,7 @@ static void ldom_startcpu_cpuid(unsigned int cpu, unsigned long thread_reg,
 	unsigned long hv_err;
 	int i;
 
-	hdesc = kzalloc(sizeof(*hdesc) +
-			(sizeof(struct hvtramp_mapping) *
-			 num_kernel_image_mappings - 1),
+	hdesc = kzalloc(struct_size(hdesc, maps, num_kernel_image_mappings),
 			GFP_KERNEL);
 	if (!hdesc) {
 		printk(KERN_ERR "ldom_startcpu_cpuid: Cannot allocate "
-- 
2.47.0