[PATCH v2 12/30] gpu: nova-core: add support for 32-bit firmware images

[John Hubbard <jhubbard@nvidia.com>]

Add Elf32Hdr and Elf32SHdr newtypes, implement the ElfHeader and
ElfSectionHeader traits for them, and add elf32_section().

This mirrors the existing ELF64 support, using the same generic
infrastructure.

Signed-off-by: John Hubbard <jhubbard@nvidia.com>
---
 drivers/gpu/nova-core/firmware.rs | 46 +++++++++++++++++++++++++++++++
 1 file changed, 46 insertions(+)

diff --git a/drivers/gpu/nova-core/firmware.rs b/drivers/gpu/nova-core/firmware.rs
index 6ed76a7e15f1..5f3f878eef71 100644
--- a/drivers/gpu/nova-core/firmware.rs
+++ b/drivers/gpu/nova-core/firmware.rs
@@ -507,6 +507,46 @@ fn size(&self) -> u64 {
         }
     }
 
+    /// Newtype to provide [`FromBytes`] and [`ElfHeader`] implementations for ELF32.
+    #[repr(transparent)]
+    struct Elf32Hdr(bindings::elf32_hdr);
+    // SAFETY: all bit patterns are valid for this type, and it doesn't use interior mutability.
+    unsafe impl FromBytes for Elf32Hdr {}
+
+    impl ElfHeader for Elf32Hdr {
+        fn shnum(&self) -> u16 {
+            self.0.e_shnum
+        }
+
+        fn shoff(&self) -> u64 {
+            u64::from(self.0.e_shoff)
+        }
+
+        fn shstrndx(&self) -> u16 {
+            self.0.e_shstrndx
+        }
+    }
+
+    /// Newtype to provide [`FromBytes`] and [`ElfSectionHeader`] implementations for ELF32.
+    #[repr(transparent)]
+    struct Elf32SHdr(bindings::elf32_shdr);
+    // SAFETY: all bit patterns are valid for this type, and it doesn't use interior mutability.
+    unsafe impl FromBytes for Elf32SHdr {}
+
+    impl ElfSectionHeader for Elf32SHdr {
+        fn name(&self) -> u32 {
+            self.0.sh_name
+        }
+
+        fn offset(&self) -> u64 {
+            u64::from(self.0.sh_offset)
+        }
+
+        fn size(&self) -> u64 {
+            u64::from(self.0.sh_size)
+        }
+    }
+
     /// Returns a NULL-terminated string from the ELF image at `offset`.
     fn elf_str(elf: &[u8], offset: u64) -> Option<&str> {
         let idx = usize::try_from(offset).ok()?;
@@ -559,4 +599,10 @@ fn elf_section_generic<'a, H, S>(elf: &'a [u8], name: &str) -> Option<&'a [u8]>
     pub(super) fn elf64_section<'a>(elf: &'a [u8], name: &str) -> Option<&'a [u8]> {
         elf_section_generic::<Elf64Hdr, Elf64SHdr>(elf, name)
     }
+
+    /// Extract section with name `name` from the ELF32 image `elf`.
+    #[expect(dead_code)]
+    pub(super) fn elf32_section<'a>(elf: &'a [u8], name: &str) -> Option<&'a [u8]> {
+        elf_section_generic::<Elf32Hdr, Elf32SHdr>(elf, name)
+    }
 }
-- 
2.52.0