arm/optee-os: Backport the clang fixes

diff --git a/meta-arm/recipes-security/optee/optee-os/0001-arm64.h-fix-compile-error-with-Clang.patch b/meta-arm/recipes-security/optee/optee-os/0001-arm64.h-fix-compile-error-with-Clang.patch
new file mode 100644
index 000000000000..e4508b3435c6
--- /dev/null
+++ b/meta-arm/recipes-security/optee/optee-os/0001-arm64.h-fix-compile-error-with-Clang.patch
@@ -0,0 +1,70 @@ 
+From dc9fd53be9d69c4a6bc67d9de951b8f2a92abade Mon Sep 17 00:00:00 2001
+From: Jerome Forissier <jerome.forissier@linaro.org>
+Date: Fri, 14 Jun 2024 17:51:22 +0200
+Subject: [PATCH 1/2] arm64.h: fix compile error with Clang
+
+Clang 18.1.6 fails to compile OP-TEE OS with the following error:
+
+   CC      out/arm/core/arch/arm/kernel/vfp.o
+ In file included from core/arch/arm/kernel/vfp.c:6:
+ In file included from core/arch/arm/include/arm.h:137:
+ core/arch/arm/include/arm64.h:455:1: error: expected readable system register
+   455 | DEFINE_U32_REG_READWRITE_FUNCS(fpcr)
+       | ^
+ core/arch/arm/include/arm64.h:436:3: note: expanded from macro 'DEFINE_U32_REG_READWRITE_FUNCS'
+   436 |                 DEFINE_U32_REG_READ_FUNC(reg)   \
+       |                 ^
+ core/arch/arm/include/arm64.h:430:3: note: expanded from macro 'DEFINE_U32_REG_READ_FUNC'
+   430 |                 DEFINE_REG_READ_FUNC_(reg, uint32_t, reg)
+       |                 ^
+ core/arch/arm/include/arm64.h:417:15: note: expanded from macro 'DEFINE_REG_READ_FUNC_'
+   417 |         asm volatile("mrs %0, " #asmreg : "=r" (val64));        \
+       |                      ^
+ <inline asm>:1:10: note: instantiated into assembly here
+     1 |         mrs x8, fpcr
+       |                 ^
+
+...and similar ones for fpcr write, as well as fpsr read and write.
+
+Clang 12.0.0 does not have any problem with this code which makes me
+think that it's a Clang/LLVM issue.
+
+Work around the problem by using the coded system register identifiers
+S3_3_c4_c4_0 and S3_3_c4_c4_1 instead of fpcr and fpsr, respectively.
+The values 3-3-4-4-0 and 3-3-4-4-1 are taken from the Arm ARM sections
+C.5.2.8 and C.5.2.9.
+
+Signed-off-by: Jerome Forissier <jerome.forissier@linaro.org>
+Acked-by: Joakim Bech <joakim.bech@linaro.org>
+Acked-by: Jens Wiklander <jens.wiklander@linaro.org>
+
+Upstream-Status: Backport
+Signed-off-by: Jon Mason <jon.mason@arm.com>
+
+---
+ core/arch/arm/include/arm64.h | 7 +++++++
+ 1 file changed, 7 insertions(+)
+
+diff --git a/core/arch/arm/include/arm64.h b/core/arch/arm/include/arm64.h
+index 28922631f637..c72b5cd7bbd3 100644
+--- a/core/arch/arm/include/arm64.h
++++ b/core/arch/arm/include/arm64.h
+@@ -452,8 +452,15 @@ static inline __noprof void write_##reg(type val)		\
+ 
+ DEFINE_U32_REG_READWRITE_FUNCS(cpacr_el1)
+ DEFINE_U32_REG_READWRITE_FUNCS(daif)
++#ifdef __clang__
++DEFINE_REG_READ_FUNC_(fpcr, uint32_t, S3_3_c4_c4_0)
++DEFINE_REG_WRITE_FUNC_(fpcr, uint32_t, S3_3_c4_c4_0)
++DEFINE_REG_READ_FUNC_(fpsr, uint32_t, S3_3_c4_c4_1)
++DEFINE_REG_WRITE_FUNC_(fpsr, uint32_t, S3_3_c4_c4_1)
++#else
+ DEFINE_U32_REG_READWRITE_FUNCS(fpcr)
+ DEFINE_U32_REG_READWRITE_FUNCS(fpsr)
++#endif
+ 
+ DEFINE_U32_REG_READ_FUNC(ctr_el0)
+ #define read_ctr() read_ctr_el0()
+-- 
+2.39.5
+
diff --git a/meta-arm/recipes-security/optee/optee-os/0002-libutils-zlib-fix-Clang-warnings.patch b/meta-arm/recipes-security/optee/optee-os/0002-libutils-zlib-fix-Clang-warnings.patch
new file mode 100644
index 000000000000..fb50fecbd01b
--- /dev/null
+++ b/meta-arm/recipes-security/optee/optee-os/0002-libutils-zlib-fix-Clang-warnings.patch
@@ -0,0 +1,64 @@ 
+From 47d5e6cbd61a38d1c31538e6b1775b901273fdec Mon Sep 17 00:00:00 2001
+From: Jerome Forissier <jerome.forissier@linaro.org>
+Date: Fri, 14 Jun 2024 18:40:53 +0200
+Subject: [PATCH 2/2] libutils, zlib: fix Clang warnings
+
+Clang 18.1.6 reports the following warnings:
+
+   CC      out/arm/ldelf-lib/libutils/isoc/bget_malloc.o
+ In file included from lib/libutils/isoc/bget_malloc.c:127:
+ lib/libutils/isoc/bget.c:607:7: warning: a function definition without a prototype is deprecated in all versions of C and is not supported in C23 [-Wdeprecated-non-prototype]
+   607 | void *bget(requested_align, hdr_size, requested_size, poolset)
+       |       ^
+
+And same with lib/zlib/{adler32.c,inffast.c,inflate.c,zutil.c}.
+
+In addition, zutil.c causes:
+
+  CC      out/arm/core/lib/zlib/zutil.o
+core/lib/zlib/zutil.c:28:33: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
+   28 | const char * ZEXPORT zlibVersion()
+      |                                 ^
+      |                                  void
+
+Add -Wno-deprecated-non-prototype to libutils' bget_malloc.c to silence
+the first series, and simply remove -Wstrict-prototypes (added by
+default by mk/compile.mk) when building zlib.
+
+Signed-off-by: Jerome Forissier <jerome.forissier@linaro.org>
+Acked-by: Joakim Bech <joakim.bech@linaro.org>
+Acked-by: Jens Wiklander <jens.wiklander@linaro.org>
+
+Upstream-Status: Backport
+Signed-off-by: Jon Mason <jon.mason@arm.com>
+
+---
+ core/lib/zlib/sub.mk     | 2 ++
+ lib/libutils/isoc/sub.mk | 1 +
+ 2 files changed, 3 insertions(+)
+
+diff --git a/core/lib/zlib/sub.mk b/core/lib/zlib/sub.mk
+index d4f225dfbfc4..399544d02e20 100644
+--- a/core/lib/zlib/sub.mk
++++ b/core/lib/zlib/sub.mk
+@@ -6,3 +6,5 @@ srcs-y += inftrees.c
+ srcs-y += zutil.c
+ cflags-remove-y += -Wold-style-definition
+ cflags-remove-y += -Wswitch-default
++cflags-remove-y += -Wstrict-prototypes
++cflags-y += $(call cc-option,-Wno-deprecated-non-prototype)
+diff --git a/lib/libutils/isoc/sub.mk b/lib/libutils/isoc/sub.mk
+index ef1ca5da8cf0..705090211627 100644
+--- a/lib/libutils/isoc/sub.mk
++++ b/lib/libutils/isoc/sub.mk
+@@ -3,6 +3,7 @@ global-incdirs-y += include
+ srcs-y += bget_malloc.c
+ cflags-remove-bget_malloc.c-y += -Wold-style-definition -Wredundant-decls
+ cflags-bget_malloc.c-y += -Wno-sign-compare -Wno-cast-align
++cflags-bget_malloc.c-y += $(call cc-option,-Wno-deprecated-non-prototype)
+ ifeq ($(sm),core)
+ cflags-remove-bget_malloc.c-y += $(cflags_kasan)
+ endif
+-- 
+2.39.5
+
diff --git a/meta-arm/recipes-security/optee/optee-os_4.2.0.bb b/meta-arm/recipes-security/optee/optee-os_4.2.0.bb
index 33c19f2fa349..3f00c7b3617f 100644
--- a/meta-arm/recipes-security/optee/optee-os_4.2.0.bb
+++ b/meta-arm/recipes-security/optee/optee-os_4.2.0.bb
@@ -12,4 +12,6 @@  SRC_URI += " \
     file://0001-compile.mk-use-CFLAGS-from-environment.patch \
     file://0002-link.mk-use-CFLAGS-with-version.o.patch \
     file://0003-link.mk-generate-version.o-in-link-out-dir.patch \
+    file://0001-arm64.h-fix-compile-error-with-Clang.patch \
+    file://0002-libutils-zlib-fix-Clang-warnings.patch \
 "
diff --git a/meta-arm/recipes-security/optee/optee.inc b/meta-arm/recipes-security/optee/optee.inc
index 37676f14960c..c5514f565172 100644
--- a/meta-arm/recipes-security/optee/optee.inc
+++ b/meta-arm/recipes-security/optee/optee.inc
@@ -14,9 +14,6 @@  OPTEE_ARCH:arm = "arm32"
 OPTEE_ARCH:aarch64 = "arm64"
 OPTEE_CORE = "${@d.getVar('OPTEE_ARCH').upper()}"
 
-# FIXME - breaks with Clang 18.  See https://github.com/OP-TEE/optee_os/issues/6754
-TOOLCHAIN = "gcc"
-
 OPTEE_TOOLCHAIN = "${@d.getVar('TOOLCHAIN') or 'gcc'}"
 OPTEE_COMPILER = "${@bb.utils.contains("BBFILE_COLLECTIONS", "clang-layer", "${OPTEE_TOOLCHAIN}", "gcc", d)}"