xtensa: build kernel with text-section-literals

vmlinux.lds.S doesn't do anything special with literals, so instead of
keeping them separate put them into the corresponding text sections.
Drop explicit .literal sections from the vmlinux.lds.S, use standard
section macros. Mark literal pool locations in the assembly sources.
Unfortunately assembler doesn't put literals into .init sections and
external libgcc may still have .literal sections, so sed transformation
to the linker script is still needed.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

arch/xtensa/Makefile

@@ -42,12 +42,12 @@ export PLATFORM
 
 # temporarily until string.h is fixed
 KBUILD_CFLAGS += -ffreestanding -D__linux__
-
-KBUILD_CFLAGS += -pipe -mlongcalls
-
+KBUILD_CFLAGS += -pipe -mlongcalls -mtext-section-literals
 KBUILD_CFLAGS += $(call cc-option,-mforce-no-pic,)
 KBUILD_CFLAGS += $(call cc-option,-mno-serialize-volatile,)
 
+KBUILD_AFLAGS += -mlongcalls -mtext-section-literals
+
 ifneq ($(CONFIG_LD_NO_RELAX),)
 LDFLAGS := --no-relax
 endif

arch/xtensa/boot/boot-redboot/bootstrap.S

@@ -42,6 +42,7 @@ __start_a0:
 	.align 4
 
 	.section .text, "ax"
+	.literal_position
 	.begin literal_prefix .text
 
 	/* put literals in here! */

arch/xtensa/kernel/Makefile

@@ -17,9 +17,6 @@ obj-$(CONFIG_XTENSA_VARIANT_HAVE_PERF_EVENTS) += perf_event.o
 obj-$(CONFIG_HAVE_HW_BREAKPOINT) += hw_breakpoint.o
 obj-$(CONFIG_S32C1I_SELFTEST) += s32c1i_selftest.o
 
-AFLAGS_head.o += -mtext-section-literals
-AFLAGS_mxhead.o += -mtext-section-literals
-
 # In the Xtensa architecture, assembly generates literals which must always
 # precede the L32R instruction with a relative offset less than 256 kB.
 # Therefore, the .text and .literal section must be combined in parenthesis

arch/xtensa/kernel/align.S

@@ -155,7 +155,7 @@
  *	     <  VALID_DOUBLE_EXCEPTION_ADDRESS: regular exception
  */
 
-
+	.literal_position
 ENTRY(fast_unaligned)
 
 	/* Note: We don't expect the address to be aligned on a word

arch/xtensa/kernel/entry.S

@@ -125,6 +125,7 @@
  *
  * Note: _user_exception might be at an odd address. Don't use call0..call12
  */
+	.literal_position
 
 ENTRY(user_exception)
 
@@ -777,6 +778,8 @@ ENDPROC(kernel_exception)
  * When we get here,  a0 is trashed and saved to excsave[debuglevel]
  */
 
+	.literal_position
+
 ENTRY(debug_exception)
 
 	rsr	a0, SREG_EPS + XCHAL_DEBUGLEVEL
@@ -916,6 +919,8 @@ ENDPROC(debug_exception)
 unrecoverable_text:
 	.ascii "Unrecoverable error in exception handler\0"
 
+	.literal_position
+
 ENTRY(unrecoverable_exception)
 
 	movi	a0, 1
@@ -1117,6 +1122,8 @@ ENDPROC(fast_syscall_unrecoverable)
  *		j done
  */
 
+	.literal_position
+
 #ifdef CONFIG_FAST_SYSCALL_XTENSA
 
 #define TRY								\
@@ -1887,6 +1894,7 @@ ENDPROC(fast_store_prohibited)
  * void system_call (struct pt_regs* regs, int exccause)
  *                            a2                 a3
  */
+	.literal_position
 
 ENTRY(system_call)
 

arch/xtensa/kernel/setup.c

@@ -277,13 +277,13 @@ extern char _end[];
 extern char _stext[];
 extern char _WindowVectors_text_start;
 extern char _WindowVectors_text_end;
-extern char _DebugInterruptVector_literal_start;
+extern char _DebugInterruptVector_text_start;
 extern char _DebugInterruptVector_text_end;
-extern char _KernelExceptionVector_literal_start;
+extern char _KernelExceptionVector_text_start;
 extern char _KernelExceptionVector_text_end;
-extern char _UserExceptionVector_literal_start;
+extern char _UserExceptionVector_text_start;
 extern char _UserExceptionVector_text_end;
-extern char _DoubleExceptionVector_literal_start;
+extern char _DoubleExceptionVector_text_start;
 extern char _DoubleExceptionVector_text_end;
 #if XCHAL_EXCM_LEVEL >= 2
 extern char _Level2InterruptVector_text_start;
@@ -339,16 +339,16 @@ void __init setup_arch(char **cmdline_p)
 	mem_reserve(__pa(&_WindowVectors_text_start),
 		    __pa(&_WindowVectors_text_end));
 
-	mem_reserve(__pa(&_DebugInterruptVector_literal_start),
+	mem_reserve(__pa(&_DebugInterruptVector_text_start),
 		    __pa(&_DebugInterruptVector_text_end));
 
-	mem_reserve(__pa(&_KernelExceptionVector_literal_start),
+	mem_reserve(__pa(&_KernelExceptionVector_text_start),
 		    __pa(&_KernelExceptionVector_text_end));
 
-	mem_reserve(__pa(&_UserExceptionVector_literal_start),
+	mem_reserve(__pa(&_UserExceptionVector_text_start),
 		    __pa(&_UserExceptionVector_text_end));
 
-	mem_reserve(__pa(&_DoubleExceptionVector_literal_start),
+	mem_reserve(__pa(&_DoubleExceptionVector_text_start),
 		    __pa(&_DoubleExceptionVector_text_end));
 
 #if XCHAL_EXCM_LEVEL >= 2

arch/xtensa/kernel/vectors.S

@@ -205,9 +205,6 @@ ENDPROC(_KernelExceptionVector)
  */
 
 	.section .DoubleExceptionVector.text, "ax"
-	.begin literal_prefix .DoubleExceptionVector
-	.globl _DoubleExceptionVector_WindowUnderflow
-	.globl _DoubleExceptionVector_WindowOverflow
 
 ENTRY(_DoubleExceptionVector)
 
@@ -217,8 +214,12 @@ ENTRY(_DoubleExceptionVector)
 	/* Check for kernel double exception (usually fatal). */
 
 	rsr	a2, ps
-	_bbci.l	a2, PS_UM_BIT, .Lksp
+	_bbsi.l	a2, PS_UM_BIT, 1f
+	j	.Lksp
 
+	.align	4
+	.literal_position
+1:
 	/* Check if we are currently handling a window exception. */
 	/* Note: We don't need to indicate that we enter a critical section. */
 
@@ -475,11 +476,8 @@ _DoubleExceptionVector_handle_exception:
 	rotw	-3
 	j	1b
 
-
 ENDPROC(_DoubleExceptionVector)
 
-	.end literal_prefix
-
 	.text
 /*
  * Fixup handler for TLB miss in double exception handler for window owerflow.
@@ -508,6 +506,8 @@ ENDPROC(_DoubleExceptionVector)
  * a3: exctable, original value in excsave1
  */
 
+	.literal_position
+
 ENTRY(window_overflow_restore_a0_fixup)
 
 	rsr	a0, ps

arch/xtensa/kernel/vmlinux.lds.S

@@ -45,24 +45,16 @@ jiffies = jiffies_64;
 	LONG(sym ## _end);			\
 	LONG(LOADADDR(section))
 
-/* Macro to define a section for a vector.
- *
- * Use of the MIN function catches the types of errors illustrated in
- * the following example:
- *
- * Assume the section .DoubleExceptionVector.literal is completely
- * full.  Then a programmer adds code to .DoubleExceptionVector.text
- * that produces another literal.  The final literal position will
- * overlay onto the first word of the adjacent code section
- * .DoubleExceptionVector.text.  (In practice, the literals will
- * overwrite the code, and the first few instructions will be
- * garbage.)
+/*
+ * Macro to define a section for a vector. When CONFIG_VECTORS_OFFSET is
+ * defined code for every vector is located with other init data. At startup
+ * time head.S copies code for every vector to its final position according
+ * to description recorded in the corresponding RELOCATE_ENTRY.
  */
 
 #ifdef CONFIG_VECTORS_OFFSET
-#define SECTION_VECTOR(sym, section, addr, max_prevsec_size, prevsec)       \
-  section addr : AT((MIN(LOADADDR(prevsec) + max_prevsec_size,		    \
-		         LOADADDR(prevsec) + SIZEOF(prevsec)) + 3) & ~ 3)   \
+#define SECTION_VECTOR(sym, section, addr, prevsec)                         \
+  section addr : AT(((LOADADDR(prevsec) + SIZEOF(prevsec)) + 3) & ~ 3)      \
   {									    \
     . = ALIGN(4);							    \
     sym ## _start = ABSOLUTE(.);		 			    \
@@ -112,26 +104,19 @@ SECTIONS
 #if XCHAL_EXCM_LEVEL >= 6
   SECTION_VECTOR (.Level6InterruptVector.text, INTLEVEL6_VECTOR_VADDR)
 #endif
-  SECTION_VECTOR (.DebugInterruptVector.literal, DEBUG_VECTOR_VADDR - 4)
   SECTION_VECTOR (.DebugInterruptVector.text, DEBUG_VECTOR_VADDR)
-  SECTION_VECTOR (.KernelExceptionVector.literal, KERNEL_VECTOR_VADDR - 4)
   SECTION_VECTOR (.KernelExceptionVector.text, KERNEL_VECTOR_VADDR)
-  SECTION_VECTOR (.UserExceptionVector.literal, USER_VECTOR_VADDR - 4)
   SECTION_VECTOR (.UserExceptionVector.text, USER_VECTOR_VADDR)
-  SECTION_VECTOR (.DoubleExceptionVector.literal, DOUBLEEXC_VECTOR_VADDR - 20)
   SECTION_VECTOR (.DoubleExceptionVector.text, DOUBLEEXC_VECTOR_VADDR)
 #endif
 
+    IRQENTRY_TEXT
+    SOFTIRQENTRY_TEXT
+    ENTRY_TEXT
     TEXT_TEXT
-    VMLINUX_SYMBOL(__sched_text_start) = .;
-    *(.sched.literal .sched.text)
-    VMLINUX_SYMBOL(__sched_text_end) = .;
-    VMLINUX_SYMBOL(__cpuidle_text_start) = .;
-    *(.cpuidle.literal .cpuidle.text)
-    VMLINUX_SYMBOL(__cpuidle_text_end) = .;
-    VMLINUX_SYMBOL(__lock_text_start) = .;
-    *(.spinlock.literal .spinlock.text)
-    VMLINUX_SYMBOL(__lock_text_end) = .;
+    SCHED_TEXT
+    CPUIDLE_TEXT
+    LOCK_TEXT
 
   }
   _etext = .;
@@ -196,8 +181,6 @@ SECTIONS
 		   .KernelExceptionVector.text);
     RELOCATE_ENTRY(_UserExceptionVector_text,
 		   .UserExceptionVector.text);
-    RELOCATE_ENTRY(_DoubleExceptionVector_literal,
-		   .DoubleExceptionVector.literal);
     RELOCATE_ENTRY(_DoubleExceptionVector_text,
 		   .DoubleExceptionVector.text);
     RELOCATE_ENTRY(_DebugInterruptVector_text,
@@ -230,25 +213,19 @@ SECTIONS
 
   SECTION_VECTOR (_WindowVectors_text,
 		  .WindowVectors.text,
-		  WINDOW_VECTORS_VADDR, 4,
+		  WINDOW_VECTORS_VADDR,
 		  .dummy)
-  SECTION_VECTOR (_DebugInterruptVector_literal,
-		  .DebugInterruptVector.literal,
-		  DEBUG_VECTOR_VADDR - 4,
-		  SIZEOF(.WindowVectors.text),
-		  .WindowVectors.text)
   SECTION_VECTOR (_DebugInterruptVector_text,
 		  .DebugInterruptVector.text,
 		  DEBUG_VECTOR_VADDR,
-		  4,
-		  .DebugInterruptVector.literal)
+		  .WindowVectors.text)
 #undef LAST
 #define LAST	.DebugInterruptVector.text
 #if XCHAL_EXCM_LEVEL >= 2
   SECTION_VECTOR (_Level2InterruptVector_text,
 		  .Level2InterruptVector.text,
 		  INTLEVEL2_VECTOR_VADDR,
-		  SIZEOF(LAST), LAST)
+		  LAST)
 # undef LAST
 # define LAST	.Level2InterruptVector.text
 #endif
@@ -256,7 +233,7 @@ SECTIONS
   SECTION_VECTOR (_Level3InterruptVector_text,
 		  .Level3InterruptVector.text,
 		  INTLEVEL3_VECTOR_VADDR,
-		  SIZEOF(LAST), LAST)
+		  LAST)
 # undef LAST
 # define LAST	.Level3InterruptVector.text
 #endif
@@ -264,7 +241,7 @@ SECTIONS
   SECTION_VECTOR (_Level4InterruptVector_text,
 		  .Level4InterruptVector.text,
 		  INTLEVEL4_VECTOR_VADDR,
-		  SIZEOF(LAST), LAST)
+		  LAST)
 # undef LAST
 # define LAST	.Level4InterruptVector.text
 #endif
@@ -272,7 +249,7 @@ SECTIONS
   SECTION_VECTOR (_Level5InterruptVector_text,
 		  .Level5InterruptVector.text,
 		  INTLEVEL5_VECTOR_VADDR,
-		  SIZEOF(LAST), LAST)
+		  LAST)
 # undef LAST
 # define LAST	.Level5InterruptVector.text
 #endif
@@ -280,40 +257,23 @@ SECTIONS
   SECTION_VECTOR (_Level6InterruptVector_text,
 		  .Level6InterruptVector.text,
 		  INTLEVEL6_VECTOR_VADDR,
-		  SIZEOF(LAST), LAST)
+		  LAST)
 # undef LAST
 # define LAST	.Level6InterruptVector.text
 #endif
-  SECTION_VECTOR (_KernelExceptionVector_literal,
-		  .KernelExceptionVector.literal,
-		  KERNEL_VECTOR_VADDR - 4,
-		  SIZEOF(LAST), LAST)
-#undef LAST
   SECTION_VECTOR (_KernelExceptionVector_text,
 		  .KernelExceptionVector.text,
 		  KERNEL_VECTOR_VADDR,
-		  4,
-		  .KernelExceptionVector.literal)
-  SECTION_VECTOR (_UserExceptionVector_literal,
-		  .UserExceptionVector.literal,
-		  USER_VECTOR_VADDR - 4,
-		  SIZEOF(.KernelExceptionVector.text),
-		  .KernelExceptionVector.text)
+		  LAST)
+#undef LAST
   SECTION_VECTOR (_UserExceptionVector_text,
 		  .UserExceptionVector.text,
 		  USER_VECTOR_VADDR,
-		  4,
-		  .UserExceptionVector.literal)
-  SECTION_VECTOR (_DoubleExceptionVector_literal,
-		  .DoubleExceptionVector.literal,
-		  DOUBLEEXC_VECTOR_VADDR - 20,
-		  SIZEOF(.UserExceptionVector.text),
-		  .UserExceptionVector.text)
+		  .KernelExceptionVector.text)
   SECTION_VECTOR (_DoubleExceptionVector_text,
 		  .DoubleExceptionVector.text,
 		  DOUBLEEXC_VECTOR_VADDR,
-		  20,
-		  .DoubleExceptionVector.literal)
+		  .UserExceptionVector.text)
 
   . = (LOADADDR( .DoubleExceptionVector.text ) + SIZEOF( .DoubleExceptionVector.text ) + 3) & ~ 3;
 
@@ -323,7 +283,6 @@ SECTIONS
   SECTION_VECTOR (_SecondaryResetVector_text,
 		  .SecondaryResetVector.text,
 		  RESET_VECTOR1_VADDR,
-		  SIZEOF(.DoubleExceptionVector.text),
 		  .DoubleExceptionVector.text)
 
   . = LOADADDR(.SecondaryResetVector.text)+SIZEOF(.SecondaryResetVector.text);
@@ -373,5 +332,4 @@ SECTIONS
 
   /* Sections to be discarded */
   DISCARDS
-  /DISCARD/ : { *(.exit.literal) }
 }