commonlib: Substitude macro "__unused" in compiler.h

Since there are many identifiers whose name contain "__unused" in
headers of musl libc, introducing a macro which expands "__unused" to
the source of a util may have disastrous effect during its compiling
under a musl-based platform.

However, it is hard to detect musl at build time as musl is notorious
for having explicitly been refusing to add a macro like "__MUSL__" to
announce its own presence.

Using __always_unused and __maybe_unused for everything may be a good
idea. This is how it works in the Linux kernel, so that would at least
make us match some other standard rather than doing our own thing
(especially since the other compiler.h shorthand macros are also
inspired by Linux).

Signed-off-by: Bill XIE <persmule@hardenedlinux.org>
Change-Id: I547ae3371d7568f5aed732ceefe0130a339716a9
Reviewed-on: https://review.coreboot.org/c/coreboot/+/65717
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Felix Singer <felixsinger@posteo.net>
Reviewed-by: Julius Werner <jwerner@chromium.org>

2 files changed, 8 insertions, 4 deletions

diff --git a/src/soc/amd/common/block/lpc/spi_dma.c b/src/soc/amd/common/block/lpc/spi_dma.c
index 97ba2be24435..8fbd9bd71027 100644
--- a/src/soc/amd/common/block/lpc/spi_dma.c
+++ b/src/soc/amd/common/block/lpc/spi_dma.c
@@ -26,7 +26,8 @@ struct spi_dma_transaction {
 	size_t remaining;
 };
 
-static void *spi_dma_mmap(const struct region_device *rd, size_t offset, size_t size __unused)
+static void *spi_dma_mmap(const struct region_device *rd, size_t offset,
+			  size_t size __always_unused)
 {
 	const struct mem_region_device *mdev;
 
@@ -35,7 +36,8 @@ static void *spi_dma_mmap(const struct region_device *rd, size_t offset, size_t
 	return &mdev->base[offset];
 }
 
-static int spi_dma_munmap(const struct region_device *rd __unused, void *mapping __unused)
+static int spi_dma_munmap(const struct region_device *rd __always_unused,
+			  void *mapping __always_unused)
 {
 	return 0;
 }
diff --git a/src/soc/amd/common/psp_verstage/boot_dev.c b/src/soc/amd/common/psp_verstage/boot_dev.c
index 5b25d5962485..4ee78b834912 100644
--- a/src/soc/amd/common/psp_verstage/boot_dev.c
+++ b/src/soc/amd/common/psp_verstage/boot_dev.c
@@ -11,7 +11,8 @@
 
 #define DEST_BUF_ALIGNMENT 16
 
-static void *boot_dev_mmap(const struct region_device *rd, size_t offset, size_t size __unused)
+static void *boot_dev_mmap(const struct region_device *rd, size_t offset,
+			   size_t size __always_unused)
 {
 	const struct mem_region_device *mdev;
 
@@ -20,7 +21,8 @@ static void *boot_dev_mmap(const struct region_device *rd, size_t offset, size_t
 	return &(mdev->base[offset]);
 }
 
-static int boot_dev_munmap(const struct region_device *rd __unused, void *mapping __unused)
+static int boot_dev_munmap(const struct region_device *rd __always_unused,
+			   void *mapping __always_unused)
 {
 	return 0;
 }