linux-kernel - [tip: timers/vdso] parisc: Inline a type punning version of get_unaligned

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Message-ID: <176831205022.510.18385399134954753660.tip-bot2@tip-bot2>
Date: Tue, 13 Jan 2026 13:47:30 -0000
From: "tip-bot2 for Ian Rogers" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Ian Rogers <irogers@...gle.com>, Thomas Gleixner <tglx@...nel.org>,
 x86@...nel.org, linux-kernel@...r.kernel.org
Subject: [tip: timers/vdso] parisc: Inline a type punning version of
 get_unaligned_le32()

The following commit has been merged into the timers/vdso branch of tip:

Commit-ID:     feffe3a9d4b0d1672db4c16457f029f1c22b35da
Gitweb:        https://git.kernel.org/tip/feffe3a9d4b0d1672db4c16457f029f1c22b35da
Author:        Ian Rogers <irogers@...gle.com>
AuthorDate:    Thu, 16 Oct 2025 13:51:23 -07:00
Committer:     Thomas Gleixner <tglx@...nel.org>
CommitterDate: Tue, 13 Jan 2026 14:46:00 +01:00

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@...gle.com>
Signed-off-by: Thomas Gleixner <tglx@...nel.org>
Link: https://patch.msgid.link/20251016205126.2882625-2-irogers@google.com
---
 arch/parisc/boot/compressed/misc.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/arch/parisc/boot/compressed/misc.c b/arch/parisc/boot/compressed/misc.c
index 9c83bd0..111f267 100644
--- 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;
 
 	/*