x86/asm: Re-add parts of the manual CFI infrastructure

Commit:

  131484c8da97 ("x86/debug: Remove perpetually broken, unmaintainable dwarf annotations")

removed all the manual DWARF annotations outside the vDSO.  It also removed
the macros we used for the manual annotations.

Re-add these macros so that we can clean up the vDSO annotations.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/4c70bb98a8b773c8ccfaabf6745e569ff43e7f65.1444091584.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index 747860c696e1d5a4f7670c3b7b8d6127d2fdeb9f..2dfaa72260b41fcb3c9ef528ceffa9840cfc691d 100644 (file)
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -159,6 +159,12 @@ endif
 sp-$(CONFIG_X86_32) := esp
 sp-$(CONFIG_X86_64) := rsp
 
+# do binutils support CFI?
+cfi := $(call as-instr,.cfi_startproc\n.cfi_rel_offset $(sp-y)$(comma)0\n.cfi_endproc,-DCONFIG_AS_CFI=1)
+# is .cfi_signal_frame supported too?
+cfi-sigframe := $(call as-instr,.cfi_startproc\n.cfi_signal_frame\n.cfi_endproc,-DCONFIG_AS_CFI_SIGNAL_FRAME=1)
+cfi-sections := $(call as-instr,.cfi_sections .debug_frame,-DCONFIG_AS_CFI_SECTIONS=1)
+
 # does binutils support specific instructions?
 asinstr := $(call as-instr,fxsaveq (%rax),-DCONFIG_AS_FXSAVEQ=1)
 asinstr += $(call as-instr,pshufb %xmm0$(comma)%xmm0,-DCONFIG_AS_SSSE3=1)
@@ -166,8 +172,8 @@ asinstr += $(call as-instr,crc32l %eax$(comma)%eax,-DCONFIG_AS_CRC32=1)
 avx_instr := $(call as-instr,vxorps %ymm0$(comma)%ymm1$(comma)%ymm2,-DCONFIG_AS_AVX=1)
 avx2_instr :=$(call as-instr,vpbroadcastb %xmm0$(comma)%ymm1,-DCONFIG_AS_AVX2=1)
 
-KBUILD_AFLAGS += $(asinstr) $(avx_instr) $(avx2_instr)
-KBUILD_CFLAGS += $(asinstr) $(avx_instr) $(avx2_instr)
+KBUILD_AFLAGS += $(cfi) $(cfi-sigframe) $(cfi-sections) $(asinstr) $(avx_instr) $(avx2_instr)
+KBUILD_CFLAGS += $(cfi) $(cfi-sigframe) $(cfi-sections) $(asinstr) $(avx_instr) $(avx2_instr)
 
 LDFLAGS := -m elf_$(UTS_MACHINE)
 

diff --git a/arch/x86/include/asm/dwarf2.h b/arch/x86/include/asm/dwarf2.h
new file mode 100644 (file)
index 0000000..de1cdaf
--- /dev/null
+++ b/arch/x86/include/asm/dwarf2.h
@@ -0,0 +1,170 @@
+#ifndef _ASM_X86_DWARF2_H
+#define _ASM_X86_DWARF2_H
+
+#ifndef __ASSEMBLY__
+#warning "asm/dwarf2.h should be only included in pure assembly files"
+#endif
+
+/*
+ * Macros for dwarf2 CFI unwind table entries.
+ * See "as.info" for details on these pseudo ops. Unfortunately
+ * they are only supported in very new binutils, so define them
+ * away for older version.
+ */
+
+#ifdef CONFIG_AS_CFI
+
+#define CFI_STARTPROC          .cfi_startproc
+#define CFI_ENDPROC            .cfi_endproc
+#define CFI_DEF_CFA            .cfi_def_cfa
+#define CFI_DEF_CFA_REGISTER   .cfi_def_cfa_register
+#define CFI_DEF_CFA_OFFSET     .cfi_def_cfa_offset
+#define CFI_ADJUST_CFA_OFFSET  .cfi_adjust_cfa_offset
+#define CFI_OFFSET             .cfi_offset
+#define CFI_REL_OFFSET         .cfi_rel_offset
+#define CFI_REGISTER           .cfi_register
+#define CFI_RESTORE            .cfi_restore
+#define CFI_REMEMBER_STATE     .cfi_remember_state
+#define CFI_RESTORE_STATE      .cfi_restore_state
+#define CFI_UNDEFINED          .cfi_undefined
+#define CFI_ESCAPE             .cfi_escape
+
+#ifdef CONFIG_AS_CFI_SIGNAL_FRAME
+#define CFI_SIGNAL_FRAME       .cfi_signal_frame
+#else
+#define CFI_SIGNAL_FRAME
+#endif
+
+#if defined(CONFIG_AS_CFI_SECTIONS) && defined(__ASSEMBLY__)
+       /*
+        * Emit CFI data in .debug_frame sections, not .eh_frame sections.
+        * The latter we currently just discard since we don't do DWARF
+        * unwinding at runtime.  So only the offline DWARF information is
+        * useful to anyone.  Note we should not use this directive if this
+        * file is used in the vDSO assembly, or if vmlinux.lds.S gets
+        * changed so it doesn't discard .eh_frame.
+        */
+       .cfi_sections .debug_frame
+#endif
+
+#else
+
+/*
+ * Due to the structure of pre-exisiting code, don't use assembler line
+ * comment character # to ignore the arguments. Instead, use a dummy macro.
+ */
+.macro cfi_ignore a=0, b=0, c=0, d=0
+.endm
+
+#define CFI_STARTPROC          cfi_ignore
+#define CFI_ENDPROC            cfi_ignore
+#define CFI_DEF_CFA            cfi_ignore
+#define CFI_DEF_CFA_REGISTER   cfi_ignore
+#define CFI_DEF_CFA_OFFSET     cfi_ignore
+#define CFI_ADJUST_CFA_OFFSET  cfi_ignore
+#define CFI_OFFSET             cfi_ignore
+#define CFI_REL_OFFSET         cfi_ignore
+#define CFI_REGISTER           cfi_ignore
+#define CFI_RESTORE            cfi_ignore
+#define CFI_REMEMBER_STATE     cfi_ignore
+#define CFI_RESTORE_STATE      cfi_ignore
+#define CFI_UNDEFINED          cfi_ignore
+#define CFI_ESCAPE             cfi_ignore
+#define CFI_SIGNAL_FRAME       cfi_ignore
+
+#endif
+
+/*
+ * An attempt to make CFI annotations more or less
+ * correct and shorter. It is implied that you know
+ * what you're doing if you use them.
+ */
+#ifdef __ASSEMBLY__
+#ifdef CONFIG_X86_64
+       .macro pushq_cfi reg
+       pushq \reg
+       CFI_ADJUST_CFA_OFFSET 8
+       .endm
+
+       .macro pushq_cfi_reg reg
+       pushq %\reg
+       CFI_ADJUST_CFA_OFFSET 8
+       CFI_REL_OFFSET \reg, 0
+       .endm
+
+       .macro popq_cfi reg
+       popq \reg
+       CFI_ADJUST_CFA_OFFSET -8
+       .endm
+
+       .macro popq_cfi_reg reg
+       popq %\reg
+       CFI_ADJUST_CFA_OFFSET -8
+       CFI_RESTORE \reg
+       .endm
+
+       .macro pushfq_cfi
+       pushfq
+       CFI_ADJUST_CFA_OFFSET 8
+       .endm
+
+       .macro popfq_cfi
+       popfq
+       CFI_ADJUST_CFA_OFFSET -8
+       .endm
+
+       .macro movq_cfi reg offset=0
+       movq %\reg, \offset(%rsp)
+       CFI_REL_OFFSET \reg, \offset
+       .endm
+
+       .macro movq_cfi_restore offset reg
+       movq \offset(%rsp), %\reg
+       CFI_RESTORE \reg
+       .endm
+#else /*!CONFIG_X86_64*/
+       .macro pushl_cfi reg
+       pushl \reg
+       CFI_ADJUST_CFA_OFFSET 4
+       .endm
+
+       .macro pushl_cfi_reg reg
+       pushl %\reg
+       CFI_ADJUST_CFA_OFFSET 4
+       CFI_REL_OFFSET \reg, 0
+       .endm
+
+       .macro popl_cfi reg
+       popl \reg
+       CFI_ADJUST_CFA_OFFSET -4
+       .endm
+
+       .macro popl_cfi_reg reg
+       popl %\reg
+       CFI_ADJUST_CFA_OFFSET -4
+       CFI_RESTORE \reg
+       .endm
+
+       .macro pushfl_cfi
+       pushfl
+       CFI_ADJUST_CFA_OFFSET 4
+       .endm
+
+       .macro popfl_cfi
+       popfl
+       CFI_ADJUST_CFA_OFFSET -4
+       .endm
+
+       .macro movl_cfi reg offset=0
+       movl %\reg, \offset(%esp)
+       CFI_REL_OFFSET \reg, \offset
+       .endm
+
+       .macro movl_cfi_restore offset reg
+       movl \offset(%esp), %\reg
+       CFI_RESTORE \reg
+       .endm
+#endif /*!CONFIG_X86_64*/
+#endif /*__ASSEMBLY__*/
+
+#endif /* _ASM_X86_DWARF2_H */