- Add a "make x86_debug.config" target which enables a bunch of useful

config debug options when trying to debug an issue
 
 - A gcc12 build warnings fix
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Merge tag 'x86_build_for_v5.19_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 build updates from Borislav Petkov:

 - Add a "make x86_debug.config" target which enables a bunch of useful
   config debug options when trying to debug an issue

 - A gcc-12 build warnings fix

* tag 'x86_build_for_v5.19_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/boot: Wrap literal addresses in absolute_pointer()
  x86/configs: Add x86 debugging Kconfig fragment plus docs

Documentation/process/maintainer-tip.rst

@@ -437,6 +437,20 @@ in a private repository which allows interested people to easily pull the
 series for testing. The usual way to offer this is a git URL in the cover
 letter of the patch series.
 
+Testing
+^^^^^^^
+
+Code should be tested before submitting to the tip maintainers.  Anything
+other than minor changes should be built, booted and tested with
+comprehensive (and heavyweight) kernel debugging options enabled.
+
+These debugging options can be found in kernel/configs/x86_debug.config
+and can be added to an existing kernel config by running:
+
+	make x86_debug.config
+
+Some of these options are x86-specific and can be left out when testing
+on other architectures.
 
 Coding style notes
 ------------------

arch/x86/Makefile

@@ -313,5 +313,6 @@ define archhelp
   echo  ''
   echo  '  kvm_guest.config	- Enable Kconfig items for running this kernel as a KVM guest'
   echo  '  xen.config		- Enable Kconfig items for running this kernel as a Xen guest'
+  echo  '  x86_debug.config	- Enable tip tree debugging options for testing'
 
 endef

arch/x86/boot/boot.h

@@ -77,66 +77,78 @@ typedef unsigned int addr_t;
 
 static inline u8 rdfs8(addr_t addr)
 {
+	u8 *ptr = (u8 *)absolute_pointer(addr);
 	u8 v;
-	asm volatile("movb %%fs:%1,%0" : "=q" (v) : "m" (*(u8 *)addr));
+	asm volatile("movb %%fs:%1,%0" : "=q" (v) : "m" (*ptr));
 	return v;
 }
 static inline u16 rdfs16(addr_t addr)
 {
+	u16 *ptr = (u16 *)absolute_pointer(addr);
 	u16 v;
-	asm volatile("movw %%fs:%1,%0" : "=r" (v) : "m" (*(u16 *)addr));
+	asm volatile("movw %%fs:%1,%0" : "=r" (v) : "m" (*ptr));
 	return v;
 }
 static inline u32 rdfs32(addr_t addr)
 {
+	u32 *ptr = (u32 *)absolute_pointer(addr);
 	u32 v;
-	asm volatile("movl %%fs:%1,%0" : "=r" (v) : "m" (*(u32 *)addr));
+	asm volatile("movl %%fs:%1,%0" : "=r" (v) : "m" (*ptr));
 	return v;
 }
 
 static inline void wrfs8(u8 v, addr_t addr)
 {
-	asm volatile("movb %1,%%fs:%0" : "+m" (*(u8 *)addr) : "qi" (v));
+	u8 *ptr = (u8 *)absolute_pointer(addr);
+	asm volatile("movb %1,%%fs:%0" : "+m" (*ptr) : "qi" (v));
 }
 static inline void wrfs16(u16 v, addr_t addr)
 {
-	asm volatile("movw %1,%%fs:%0" : "+m" (*(u16 *)addr) : "ri" (v));
+	u16 *ptr = (u16 *)absolute_pointer(addr);
+	asm volatile("movw %1,%%fs:%0" : "+m" (*ptr) : "ri" (v));
 }
 static inline void wrfs32(u32 v, addr_t addr)
 {
-	asm volatile("movl %1,%%fs:%0" : "+m" (*(u32 *)addr) : "ri" (v));
+	u32 *ptr = (u32 *)absolute_pointer(addr);
+	asm volatile("movl %1,%%fs:%0" : "+m" (*ptr) : "ri" (v));
 }
 
 static inline u8 rdgs8(addr_t addr)
 {
+	u8 *ptr = (u8 *)absolute_pointer(addr);
 	u8 v;
-	asm volatile("movb %%gs:%1,%0" : "=q" (v) : "m" (*(u8 *)addr));
+	asm volatile("movb %%gs:%1,%0" : "=q" (v) : "m" (*ptr));
 	return v;
 }
 static inline u16 rdgs16(addr_t addr)
 {
+	u16 *ptr = (u16 *)absolute_pointer(addr);
 	u16 v;
-	asm volatile("movw %%gs:%1,%0" : "=r" (v) : "m" (*(u16 *)addr));
+	asm volatile("movw %%gs:%1,%0" : "=r" (v) : "m" (*ptr));
 	return v;
 }
 static inline u32 rdgs32(addr_t addr)
 {
+	u32 *ptr = (u32 *)absolute_pointer(addr);
 	u32 v;
-	asm volatile("movl %%gs:%1,%0" : "=r" (v) : "m" (*(u32 *)addr));
+	asm volatile("movl %%gs:%1,%0" : "=r" (v) : "m" (*ptr));
 	return v;
 }
 
 static inline void wrgs8(u8 v, addr_t addr)
 {
-	asm volatile("movb %1,%%gs:%0" : "+m" (*(u8 *)addr) : "qi" (v));
+	u8 *ptr = (u8 *)absolute_pointer(addr);
+	asm volatile("movb %1,%%gs:%0" : "+m" (*ptr) : "qi" (v));
 }
 static inline void wrgs16(u16 v, addr_t addr)
 {
-	asm volatile("movw %1,%%gs:%0" : "+m" (*(u16 *)addr) : "ri" (v));
+	u16 *ptr = (u16 *)absolute_pointer(addr);
+	asm volatile("movw %1,%%gs:%0" : "+m" (*ptr) : "ri" (v));
 }
 static inline void wrgs32(u32 v, addr_t addr)
 {
-	asm volatile("movl %1,%%gs:%0" : "+m" (*(u32 *)addr) : "ri" (v));
+	u32 *ptr = (u32 *)absolute_pointer(addr);
+	asm volatile("movl %1,%%gs:%0" : "+m" (*ptr) : "ri" (v));
 }
 
 /* Note: these only return true/false, not a signed return value! */

arch/x86/boot/main.c

@@ -35,7 +35,7 @@ static void copy_boot_params(void)
 		u16 cl_offset;
 	};
 	const struct old_cmdline * const oldcmd =
-		(const struct old_cmdline *)OLD_CL_ADDRESS;
+		absolute_pointer(OLD_CL_ADDRESS);
 
 	BUILD_BUG_ON(sizeof(boot_params) != 4096);
 	memcpy(&boot_params.hdr, &hdr, sizeof(hdr));

kernel/configs/x86_debug.config

@@ -0,0 +1,18 @@
+CONFIG_X86_DEBUG_FPU=y
+CONFIG_LOCK_STAT=y
+CONFIG_DEBUG_VM=y
+CONFIG_DEBUG_VM_VMACACHE=y
+CONFIG_DEBUG_VM_RB=y
+CONFIG_DEBUG_SLAB=y
+CONFIG_DEBUG_KMEMLEAK=y
+CONFIG_DEBUG_PAGEALLOC=y
+CONFIG_SLUB_DEBUG_ON=y
+CONFIG_KMEMCHECK=y
+CONFIG_DEBUG_OBJECTS=y
+CONFIG_DEBUG_OBJECTS_ENABLE_DEFAULT=1
+CONFIG_GCOV_KERNEL=y
+CONFIG_LOCKDEP=y
+CONFIG_PROVE_LOCKING=y
+CONFIG_SCHEDSTATS=y
+CONFIG_VMLINUX_VALIDATION=y
+CONFIG_DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT=y