parisc: Inline a type punning version of get_unaligned_le32()

Reading the byte/char output_len with get_unaligned_le32() can trigger
compiler warnings due to the size read. Avoid these warnings by using
type punning. This avoids issues when switching get_unaligned_t() to
__builtin_memcpy().

Signed-off-by: Ian Rogers <irogers@google.com>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Link: https://patch.msgid.link/20251016205126.2882625-2-irogers@google.com

diff --git a/arch/parisc/boot/compressed/misc.c b/arch/parisc/boot/compressed/misc.c
index 9c83bd06ef1542437d0ac1d416ba67c3b707433a..111f267230a194663b07e4fdad006e3fa5e3b6e7 100644 (file)
--- a/arch/parisc/boot/compressed/misc.c
+++ b/arch/parisc/boot/compressed/misc.c
@@ -278,6 +278,19 @@ static void parse_elf(void *output)
        free(phdrs);
 }
 
+/*
+ * The regular get_unaligned_le32 uses __builtin_memcpy which can trigger
+ * warnings when reading a byte/char output_len as an integer, as the size of a
+ * char is less than that of an integer. Use type punning and the packed
+ * attribute, which requires -fno-strict-aliasing, to work around the problem.
+ */
+static u32 punned_get_unaligned_le32(const void *p)
+{
+       const struct { __le32 x; } __packed * __get_pptr = p;
+
+       return le32_to_cpu(__get_pptr->x);
+}
+
 asmlinkage unsigned long __visible decompress_kernel(unsigned int started_wide,
                unsigned int command_line,
                const unsigned int rd_start,
@@ -309,7 +322,7 @@ asmlinkage unsigned long __visible decompress_kernel(unsigned int started_wide,
         * leave 2 MB for the stack.
         */
        vmlinux_addr = (unsigned long) &_ebss + 2*1024*1024;
-       vmlinux_len = get_unaligned_le32(&output_len);
+       vmlinux_len = punned_get_unaligned_le32(&output_len);
        output = (char *) vmlinux_addr;
 
        /*