[PATCH v2 01/11] efi_loader: add runtime memset helper

[Harsimran Singh Tungal]

Add efi_memset_runtime() for EFI runtime paths

This keeps buffer initialization in runtime-resident code after
ExitBootServices() and avoids relying on non-runtime helpers.

Reviewed-by: Ilias Apalodimas <ilias.apalodimas at linaro.org>
Signed-off-by: Harsimran Singh Tungal <harsimransingh.tungal at arm.com>

---

Changelog:
===============

v2:

Simon:

- Fix the `efi_memset_runtime()` comment and kernel-doc style
- Drop `__efi_runtime` from the header prototype
- Align the definition signature with nearby helpers
- Cast the stored byte to `u8`

 include/efi_loader.h         |  3 +++
 lib/efi_loader/efi_runtime.c | 20 ++++++++++++++++++++
 2 files changed, 23 insertions(+)

diff --git a/include/efi_loader.h b/include/efi_loader.h
index 3a4d502631c..9dfea1fd7de 100644
--- a/include/efi_loader.h
+++ b/include/efi_loader.h
@@ -1151,6 +1151,9 @@ void efi_memcpy_runtime(void *dest, const void *src, size_t n);
 /* runtime implementation of memcmp() */
 int efi_memcmp_runtime(const void *s1, const void *s2, size_t n);
 
+/* runtime implementation of memset() */
+void *efi_memset_runtime(void *dest, int c, size_t n);
+
 /* commonly used helper functions */
 u16 *efi_create_indexed_name(u16 *buffer, size_t buffer_size, const char *name,
 			     unsigned int index);
diff --git a/lib/efi_loader/efi_runtime.c b/lib/efi_loader/efi_runtime.c
index 73d4097464c..c0182931c42 100644
--- a/lib/efi_loader/efi_runtime.c
+++ b/lib/efi_loader/efi_runtime.c
@@ -233,6 +233,26 @@ int __efi_runtime efi_memcmp_runtime(const void *s1, const void *s2, size_t n)
 	return 0;
 }
 
+/**
+ * efi_memset_runtime() - fill memory area
+ *
+ * At runtime memset() is not available.
+ *
+ * @dest:	destination buffer
+ * @c:		byte value used to fill destination buffer
+ * @n:		number of bytes to set
+ * Return:	pointer to destination buffer
+ */
+__efi_runtime void *efi_memset_runtime(void *dest, int c, size_t n)
+{
+	u8 *d = dest;
+
+	for (; n; --n)
+		*d++ = (u8)c;
+
+	return dest;
+}
+
 /**
  * efi_update_table_header_crc32() - Update crc32 in table header
  *
-- 
2.34.1