Merge: Attend warnings with gcc 11&12 when building kernel and modules

MR: https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-9/-/merge_requests/1852

Bugzilla: https://bugzilla.redhat.com/2159468

Attend the warnings encountered when building CentOS Stream 9 kernel and module
for x86_64 and arm64 using GCC11 (cs9) and GCC12 (f37).

Some warnings end up being disabled usptream (-Wdangling-pointer,
-Warray-bounds for GCC12 and -Wdeprecated for the sign-file.c), so backport
these changes to align with this behavior.

A few configurations were introduced to deal with -Werror and specific warnings
depending on the toolchain and target architecture. This merge-request tries to
bring these relevant patches without breaking compilation (e.g, CONFIG_WERROR
is introduced, but not set).

https://bugzilla.redhat.com/2142659 was already opened separately to
attend the -Wstringop-overread in net/core/dev.c.

Signed-off-by: Eric Chanudet <echanude@redhat.com>

Approved-by: Vladis Dronov <vdronov@redhat.com>
Approved-by: Waiman Long <longman@redhat.com>
Approved-by: Lenny Szubowicz <lszubowi@redhat.com>
Approved-by: Prarit Bhargava <prarit@redhat.com>
Approved-by: Jonathan Toppins <jtoppins@redhat.com>
Approved-by: Jarod Wilson <jarod@redhat.com>

Signed-off-by: Herton R. Krzesinski <herton@redhat.com>

Author: Herton R. Krzesinski

Makefile

@@ -808,6 +808,10 @@ stackp-flags-$(CONFIG_STACKPROTECTOR_STRONG)      := -fstack-protector-strong
 
 KBUILD_CFLAGS += $(stackp-flags-y)
 
+KBUILD_CFLAGS-$(CONFIG_WERROR) += -Werror
+KBUILD_CFLAGS-$(CONFIG_CC_NO_ARRAY_BOUNDS) += -Wno-array-bounds
+KBUILD_CFLAGS += $(KBUILD_CFLAGS-y) $(CONFIG_CC_IMPLICIT_FALLTHROUGH)
+
 ifdef CONFIG_CC_IS_CLANG
 KBUILD_CPPFLAGS += -Qunused-arguments
 # The kernel builds with '-std=gnu11' so use of GNU extensions is acceptable.
@@ -818,17 +822,18 @@ KBUILD_CFLAGS += -Wno-gnu
 KBUILD_CFLAGS += -mno-global-merge
 else
 
-# Warn about unmarked fall-throughs in switch statement.
-# Disabled for clang while comment to attribute conversion happens and
-# https://github.com/ClangBuiltLinux/linux/issues/636 is discussed.
-KBUILD_CFLAGS += $(call cc-option,-Wimplicit-fallthrough=5,)
+# gcc inanely warns about local variables called 'main'
+KBUILD_CFLAGS += -Wno-main
 endif
 
 # These warnings generated too much noise in a regular build.
 # Use make W=1 to enable them (see scripts/Makefile.extrawarn)
 KBUILD_CFLAGS += $(call cc-disable-warning, unused-but-set-variable)
-
 KBUILD_CFLAGS += $(call cc-disable-warning, unused-const-variable)
+
+# These result in bogus false positives
+KBUILD_CFLAGS += $(call cc-disable-warning, dangling-pointer)
+
 ifdef CONFIG_FRAME_POINTER
 KBUILD_CFLAGS	+= -fno-omit-frame-pointer -fno-optimize-sibling-calls
 else
@@ -1011,12 +1016,15 @@ KBUILD_CFLAGS += -Wvla
 # disable pointer signed / unsigned warnings in gcc 4.0
 KBUILD_CFLAGS += -Wno-pointer-sign
 
+# In order to make sure new function cast mismatches are not introduced
+# in the kernel (to avoid tripping CFI checking), the kernel should be
+# globally built with -Wcast-function-type.
+KBUILD_CFLAGS += $(call cc-option, -Wcast-function-type)
+
 # disable stringop warnings in gcc 8+
 KBUILD_CFLAGS += $(call cc-disable-warning, stringop-truncation)
 
 # We'll want to enable this eventually, but it's not going away for 5.7 at least
-KBUILD_CFLAGS += $(call cc-disable-warning, zero-length-bounds)
-KBUILD_CFLAGS += -Wno-array-bounds
 KBUILD_CFLAGS += $(call cc-disable-warning, stringop-overflow)
 
 # Another good warning that we'll want to enable eventually
@@ -1368,8 +1376,8 @@ scripts_unifdef: scripts_basic
 # Install
 
 # Many distributions have the custom install script, /sbin/installkernel.
-# If DKMS is installed, 'make install' will eventually recuses back
-# to the this Makefile to build and install external modules.
+# If DKMS is installed, 'make install' will eventually recurse back
+# to this Makefile to build and install external modules.
 # Cancel sub_make_done so that options such as M=, V=, etc. are parsed.
 
 install: sub_make_done :=

arch/s390/Kconfig

@@ -124,6 +124,7 @@ config S390
 	select CPU_NO_EFFICIENT_FFS if !HAVE_MARCH_Z9_109_FEATURES
 	select DMA_OPS if PCI
 	select DYNAMIC_FTRACE if FUNCTION_TRACER
+	select GCC12_NO_ARRAY_BOUNDS
 	select GENERIC_ALLOCATOR
 	select GENERIC_CPU_AUTOPROBE
 	select GENERIC_CPU_VULNERABILITIES
@@ -707,16 +708,6 @@ config STACK_GUARD
 	  The minimum size for the stack guard should be 256 for 31 bit and
 	  512 for 64 bit.
 
-config WARN_DYNAMIC_STACK
-	def_bool n
-	prompt "Emit compiler warnings for function with dynamic stack usage"
-	help
-	  This option enables the compiler option -mwarn-dynamicstack. If the
-	  compiler supports this options generates warnings for functions
-	  that dynamically allocate stack space using alloca.
-
-	  Say N if you are unsure.
-
 endmenu
 
 menu "I/O subsystem"

arch/s390/Makefile

@@ -32,6 +32,8 @@ KBUILD_CFLAGS_DECOMPRESSOR += -fno-stack-protector
 KBUILD_CFLAGS_DECOMPRESSOR += $(call cc-disable-warning, address-of-packed-member)
 KBUILD_CFLAGS_DECOMPRESSOR += $(if $(CONFIG_DEBUG_INFO),-g)
 KBUILD_CFLAGS_DECOMPRESSOR += $(if $(CONFIG_DEBUG_INFO_DWARF4), $(call cc-option, -gdwarf-4,))
+KBUILD_CFLAGS_DECOMPRESSOR += $(if $(CONFIG_CC_NO_ARRAY_BOUNDS),-Wno-array-bounds)
+
 UTS_MACHINE	:= s390x
 STACK_SIZE	:= $(if $(CONFIG_KASAN),65536,16384)
 CHECKFLAGS	+= -D__s390__ -D__s390x__
@@ -85,13 +87,6 @@ cflags-$(CONFIG_CHECK_STACK) += -mstack-guard=$(CONFIG_STACK_GUARD)
 endif
 endif
 
-ifdef CONFIG_WARN_DYNAMIC_STACK
-  ifneq ($(call cc-option,-mwarn-dynamicstack),)
-    KBUILD_CFLAGS += -mwarn-dynamicstack
-    KBUILD_CFLAGS_DECOMPRESSOR += -mwarn-dynamicstack
-  endif
-endif
-
 ifdef CONFIG_EXPOLINE
   ifdef CONFIG_EXPOLINE_EXTERN
     KBUILD_LDFLAGS_MODULE += arch/s390/lib/expoline/expoline.o

arch/sparc/include/asm/smp_32.h

@@ -33,9 +33,6 @@ extern volatile unsigned long cpu_callin_map[NR_CPUS];
 extern cpumask_t smp_commenced_mask;
 extern struct linux_prom_registers smp_penguin_ctable;
 
-typedef void (*smpfunc_t)(unsigned long, unsigned long, unsigned long,
-		       unsigned long, unsigned long);
-
 void cpu_panic(void);
 
 /*
@@ -57,7 +54,7 @@ void smp_bogo(struct seq_file *);
 void smp_info(struct seq_file *);
 
 struct sparc32_ipi_ops {
-	void (*cross_call)(smpfunc_t func, cpumask_t mask, unsigned long arg1,
+	void (*cross_call)(void *func, cpumask_t mask, unsigned long arg1,
 			   unsigned long arg2, unsigned long arg3,
 			   unsigned long arg4);
 	void (*resched)(int cpu);
@@ -66,28 +63,28 @@ struct sparc32_ipi_ops {
 };
 extern const struct sparc32_ipi_ops *sparc32_ipi_ops;
 
-static inline void xc0(smpfunc_t func)
+static inline void xc0(void *func)
 {
 	sparc32_ipi_ops->cross_call(func, *cpu_online_mask, 0, 0, 0, 0);
 }
 
-static inline void xc1(smpfunc_t func, unsigned long arg1)
+static inline void xc1(void *func, unsigned long arg1)
 {
 	sparc32_ipi_ops->cross_call(func, *cpu_online_mask, arg1, 0, 0, 0);
 }
-static inline void xc2(smpfunc_t func, unsigned long arg1, unsigned long arg2)
+static inline void xc2(void *func, unsigned long arg1, unsigned long arg2)
 {
 	sparc32_ipi_ops->cross_call(func, *cpu_online_mask, arg1, arg2, 0, 0);
 }
 
-static inline void xc3(smpfunc_t func, unsigned long arg1, unsigned long arg2,
+static inline void xc3(void *func, unsigned long arg1, unsigned long arg2,
 		       unsigned long arg3)
 {
 	sparc32_ipi_ops->cross_call(func, *cpu_online_mask,
 				    arg1, arg2, arg3, 0);
 }
 
-static inline void xc4(smpfunc_t func, unsigned long arg1, unsigned long arg2,
+static inline void xc4(void *func, unsigned long arg1, unsigned long arg2,
 		       unsigned long arg3, unsigned long arg4)
 {
 	sparc32_ipi_ops->cross_call(func, *cpu_online_mask,

arch/sparc/kernel/leon_smp.c

@@ -359,7 +359,7 @@ void leonsmp_ipi_interrupt(void)
 }
 
 static struct smp_funcall {
-	smpfunc_t func;
+	void *func;
 	unsigned long arg1;
 	unsigned long arg2;
 	unsigned long arg3;
@@ -372,7 +372,7 @@ static struct smp_funcall {
 static DEFINE_SPINLOCK(cross_call_lock);
 
 /* Cross calls must be serialized, at least currently. */
-static void leon_cross_call(smpfunc_t func, cpumask_t mask, unsigned long arg1,
+static void leon_cross_call(void *func, cpumask_t mask, unsigned long arg1,
 			    unsigned long arg2, unsigned long arg3,
 			    unsigned long arg4)
 {
@@ -384,7 +384,7 @@ static void leon_cross_call(smpfunc_t func, cpumask_t mask, unsigned long arg1,
 
 		{
 			/* If you make changes here, make sure gcc generates proper code... */
-			register smpfunc_t f asm("i0") = func;
+			register void *f asm("i0") = func;
 			register unsigned long a1 asm("i1") = arg1;
 			register unsigned long a2 asm("i2") = arg2;
 			register unsigned long a3 asm("i3") = arg3;
@@ -444,11 +444,13 @@ static void leon_cross_call(smpfunc_t func, cpumask_t mask, unsigned long arg1,
 /* Running cross calls. */
 void leon_cross_call_irq(void)
 {
+	void (*func)(unsigned long, unsigned long, unsigned long, unsigned long,
+		     unsigned long) = ccall_info.func;
 	int i = smp_processor_id();
 
 	ccall_info.processors_in[i] = 1;
-	ccall_info.func(ccall_info.arg1, ccall_info.arg2, ccall_info.arg3,
-			ccall_info.arg4, ccall_info.arg5);
+	func(ccall_info.arg1, ccall_info.arg2, ccall_info.arg3, ccall_info.arg4,
+	     ccall_info.arg5);
 	ccall_info.processors_out[i] = 1;
 }
 

arch/sparc/kernel/sun4d_smp.c

@@ -268,7 +268,7 @@ static void sun4d_ipi_resched(int cpu)
 }
 
 static struct smp_funcall {
-	smpfunc_t func;
+	void *func;
 	unsigned long arg1;
 	unsigned long arg2;
 	unsigned long arg3;
@@ -281,7 +281,7 @@ static struct smp_funcall {
 static DEFINE_SPINLOCK(cross_call_lock);
 
 /* Cross calls must be serialized, at least currently. */
-static void sun4d_cross_call(smpfunc_t func, cpumask_t mask, unsigned long arg1,
+static void sun4d_cross_call(void *func, cpumask_t mask, unsigned long arg1,
 			     unsigned long arg2, unsigned long arg3,
 			     unsigned long arg4)
 {
@@ -296,7 +296,7 @@ static void sun4d_cross_call(smpfunc_t func, cpumask_t mask, unsigned long arg1,
 			 * If you make changes here, make sure
 			 * gcc generates proper code...
 			 */
-			register smpfunc_t f asm("i0") = func;
+			register void *f asm("i0") = func;
 			register unsigned long a1 asm("i1") = arg1;
 			register unsigned long a2 asm("i2") = arg2;
 			register unsigned long a3 asm("i3") = arg3;
@@ -353,11 +353,13 @@ static void sun4d_cross_call(smpfunc_t func, cpumask_t mask, unsigned long arg1,
 /* Running cross calls. */
 void smp4d_cross_call_irq(void)
 {
+	void (*func)(unsigned long, unsigned long, unsigned long, unsigned long,
+		     unsigned long) = ccall_info.func;
 	int i = hard_smp_processor_id();
 
 	ccall_info.processors_in[i] = 1;
-	ccall_info.func(ccall_info.arg1, ccall_info.arg2, ccall_info.arg3,
-			ccall_info.arg4, ccall_info.arg5);
+	func(ccall_info.arg1, ccall_info.arg2, ccall_info.arg3, ccall_info.arg4,
+	     ccall_info.arg5);
 	ccall_info.processors_out[i] = 1;
 }
 

arch/sparc/kernel/sun4m_smp.c

@@ -157,7 +157,7 @@ static void sun4m_ipi_mask_one(int cpu)
 }
 
 static struct smp_funcall {
-	smpfunc_t func;
+	void *func;
 	unsigned long arg1;
 	unsigned long arg2;
 	unsigned long arg3;
@@ -170,7 +170,7 @@ static struct smp_funcall {
 static DEFINE_SPINLOCK(cross_call_lock);
 
 /* Cross calls must be serialized, at least currently. */
-static void sun4m_cross_call(smpfunc_t func, cpumask_t mask, unsigned long arg1,
+static void sun4m_cross_call(void *func, cpumask_t mask, unsigned long arg1,
 			     unsigned long arg2, unsigned long arg3,
 			     unsigned long arg4)
 {
@@ -230,11 +230,13 @@ static void sun4m_cross_call(smpfunc_t func, cpumask_t mask, unsigned long arg1,
 /* Running cross calls. */
 void smp4m_cross_call_irq(void)
 {
+	void (*func)(unsigned long, unsigned long, unsigned long, unsigned long,
+		     unsigned long) = ccall_info.func;
 	int i = smp_processor_id();
 
 	ccall_info.processors_in[i] = 1;
-	ccall_info.func(ccall_info.arg1, ccall_info.arg2, ccall_info.arg3,
-			ccall_info.arg4, ccall_info.arg5);
+	func(ccall_info.arg1, ccall_info.arg2, ccall_info.arg3, ccall_info.arg4,
+	     ccall_info.arg5);
 	ccall_info.processors_out[i] = 1;
 }
 

arch/sparc/mm/srmmu.c

@@ -1636,19 +1636,19 @@ static void __init get_srmmu_type(void)
 /* Local cross-calls. */
 static void smp_flush_page_for_dma(unsigned long page)
 {
-	xc1((smpfunc_t) local_ops->page_for_dma, page);
+	xc1(local_ops->page_for_dma, page);
 	local_ops->page_for_dma(page);
 }
 
 static void smp_flush_cache_all(void)
 {
-	xc0((smpfunc_t) local_ops->cache_all);
+	xc0(local_ops->cache_all);
 	local_ops->cache_all();
 }
 
 static void smp_flush_tlb_all(void)
 {
-	xc0((smpfunc_t) local_ops->tlb_all);
+	xc0(local_ops->tlb_all);
 	local_ops->tlb_all();
 }
 
@@ -1659,7 +1659,7 @@ static void smp_flush_cache_mm(struct mm_struct *mm)
 		cpumask_copy(&cpu_mask, mm_cpumask(mm));
 		cpumask_clear_cpu(smp_processor_id(), &cpu_mask);
 		if (!cpumask_empty(&cpu_mask))
-			xc1((smpfunc_t) local_ops->cache_mm, (unsigned long) mm);
+			xc1(local_ops->cache_mm, (unsigned long)mm);
 		local_ops->cache_mm(mm);
 	}
 }
@@ -1671,7 +1671,7 @@ static void smp_flush_tlb_mm(struct mm_struct *mm)
 		cpumask_copy(&cpu_mask, mm_cpumask(mm));
 		cpumask_clear_cpu(smp_processor_id(), &cpu_mask);
 		if (!cpumask_empty(&cpu_mask)) {
-			xc1((smpfunc_t) local_ops->tlb_mm, (unsigned long) mm);
+			xc1(local_ops->tlb_mm, (unsigned long)mm);
 			if (atomic_read(&mm->mm_users) == 1 && current->active_mm == mm)
 				cpumask_copy(mm_cpumask(mm),
 					     cpumask_of(smp_processor_id()));
@@ -1691,8 +1691,8 @@ static void smp_flush_cache_range(struct vm_area_struct *vma,
 		cpumask_copy(&cpu_mask, mm_cpumask(mm));
 		cpumask_clear_cpu(smp_processor_id(), &cpu_mask);
 		if (!cpumask_empty(&cpu_mask))
-			xc3((smpfunc_t) local_ops->cache_range,
-			    (unsigned long) vma, start, end);
+			xc3(local_ops->cache_range, (unsigned long)vma, start,
+			    end);
 		local_ops->cache_range(vma, start, end);
 	}
 }
@@ -1708,8 +1708,8 @@ static void smp_flush_tlb_range(struct vm_area_struct *vma,
 		cpumask_copy(&cpu_mask, mm_cpumask(mm));
 		cpumask_clear_cpu(smp_processor_id(), &cpu_mask);
 		if (!cpumask_empty(&cpu_mask))
-			xc3((smpfunc_t) local_ops->tlb_range,
-			    (unsigned long) vma, start, end);
+			xc3(local_ops->tlb_range, (unsigned long)vma, start,
+			    end);
 		local_ops->tlb_range(vma, start, end);
 	}
 }
@@ -1723,8 +1723,7 @@ static void smp_flush_cache_page(struct vm_area_struct *vma, unsigned long page)
 		cpumask_copy(&cpu_mask, mm_cpumask(mm));
 		cpumask_clear_cpu(smp_processor_id(), &cpu_mask);
 		if (!cpumask_empty(&cpu_mask))
-			xc2((smpfunc_t) local_ops->cache_page,
-			    (unsigned long) vma, page);
+			xc2(local_ops->cache_page, (unsigned long)vma, page);
 		local_ops->cache_page(vma, page);
 	}
 }
@@ -1738,8 +1737,7 @@ static void smp_flush_tlb_page(struct vm_area_struct *vma, unsigned long page)
 		cpumask_copy(&cpu_mask, mm_cpumask(mm));
 		cpumask_clear_cpu(smp_processor_id(), &cpu_mask);
 		if (!cpumask_empty(&cpu_mask))
-			xc2((smpfunc_t) local_ops->tlb_page,
-			    (unsigned long) vma, page);
+			xc2(local_ops->tlb_page, (unsigned long)vma, page);
 		local_ops->tlb_page(vma, page);
 	}
 }
@@ -1753,7 +1751,7 @@ static void smp_flush_page_to_ram(unsigned long page)
 	 * XXX This experiment failed, research further... -DaveM
 	 */
 #if 1
-	xc1((smpfunc_t) local_ops->page_to_ram, page);
+	xc1(local_ops->page_to_ram, page);
 #endif
 	local_ops->page_to_ram(page);
 }
@@ -1764,8 +1762,7 @@ static void smp_flush_sig_insns(struct mm_struct *mm, unsigned long insn_addr)
 	cpumask_copy(&cpu_mask, mm_cpumask(mm));
 	cpumask_clear_cpu(smp_processor_id(), &cpu_mask);
 	if (!cpumask_empty(&cpu_mask))
-		xc2((smpfunc_t) local_ops->sig_insns,
-		    (unsigned long) mm, insn_addr);
+		xc2(local_ops->sig_insns, (unsigned long)mm, insn_addr);
 	local_ops->sig_insns(mm, insn_addr);
 }