MIPS: Add DWARF unwinding to assembly

This will allow kdump dumps to work correclty with MIPS and
future DWARF unwinding of the stack to give accurate tracebacks.

Signed-off-by: Corey Minyard <cminyard@mvista.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/16990/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

6 files changed, 151 insertions, 117 deletions

diff --git a/arch/mips/Makefile b/arch/mips/Makefile
index 3db0df37d66a..a96d97a806c9 100644
--- a/arch/mips/Makefile
+++ b/arch/mips/Makefile
@@ -299,6 +299,10 @@ ifdef CONFIG_64BIT
 bootvars-y      += ADDR_BITS=64
 endif
 
+# This is required to get dwarf unwinding tables into .debug_frame
+# instead of .eh_frame so we don't discard them.
+KBUILD_CFLAGS += -fno-asynchronous-unwind-tables
+
 LDFLAGS                 += -m $(ld-emul)
 
 ifdef CONFIG_MIPS
diff --git a/arch/mips/include/asm/asm.h b/arch/mips/include/asm/asm.h
index 859cf7048347..81fae23ce7cd 100644
--- a/arch/mips/include/asm/asm.h
+++ b/arch/mips/include/asm/asm.h
@@ -55,6 +55,7 @@
                 .type   symbol, @function;              \
                 .ent    symbol, 0;                      \
 symbol:         .frame  sp, 0, ra;                      \
+                .cfi_startproc;                         \
                 .insn
 
 /*
@@ -66,12 +67,14 @@ symbol:		.frame	sp, 0, ra;			\
                 .type   symbol, @function;              \
                 .ent    symbol, 0;                      \
 symbol:         .frame  sp, framesize, rpc;             \
+                .cfi_startproc;                         \
                 .insn
 
 /*
  * END - mark end of function
  */
 #define END(function)                                   \
+                .cfi_endproc;                           \
                 .end    function;                       \
                 .size   function, .-function
 
diff --git a/arch/mips/include/asm/stackframe.h b/arch/mips/include/asm/stackframe.h
index d2fb919fb235..5d3563c55e0c 100644
--- a/arch/mips/include/asm/stackframe.h
+++ b/arch/mips/include/asm/stackframe.h
@@ -19,20 +19,43 @@
 #include <asm/asm-offsets.h>
 #include <asm/thread_info.h>
 
+/* Make the addition of cfi info a little easier. */
+        .macro cfi_rel_offset reg offset=0 docfi=0
+        .if \docfi
+        .cfi_rel_offset \reg, \offset
+        .endif
+        .endm
+
+        .macro cfi_st reg offset=0 docfi=0
+        LONG_S  \reg, \offset(sp)
+        cfi_rel_offset \reg, \offset, \docfi
+        .endm
+
+        .macro cfi_restore reg offset=0 docfi=0
+        .if \docfi
+        .cfi_restore \reg
+        .endif
+        .endm
+
+        .macro cfi_ld reg offset=0 docfi=0
+        LONG_L  \reg, \offset(sp)
+        cfi_restore \reg \offset \docfi
+        .endm
+
 #if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
 #define STATMASK 0x3f
 #else
 #define STATMASK 0x1f
 #endif
 
-                .macro  SAVE_AT
+                .macro  SAVE_AT docfi=0
                 .set    push
                 .set    noat
-                LONG_S  $1, PT_R1(sp)
+                cfi_st  $1, PT_R1, \docfi
                 .set    pop
                 .endm
 
-                .macro  SAVE_TEMP
+                .macro  SAVE_TEMP docfi=0
 #ifdef CONFIG_CPU_HAS_SMARTMIPS
                 mflhxu  v1
                 LONG_S  v1, PT_LO(sp)
@@ -44,20 +67,20 @@
                 mfhi    v1
 #endif
 #ifdef CONFIG_32BIT
-                LONG_S  $8, PT_R8(sp)
-                LONG_S  $9, PT_R9(sp)
+                cfi_st  $8, PT_R8, \docfi
+                cfi_st  $9, PT_R9, \docfi
 #endif
-                LONG_S  $10, PT_R10(sp)
-                LONG_S  $11, PT_R11(sp)
-                LONG_S  $12, PT_R12(sp)
+                cfi_st  $10, PT_R10, \docfi
+                cfi_st  $11, PT_R11, \docfi
+                cfi_st  $12, PT_R12, \docfi
 #if !defined(CONFIG_CPU_HAS_SMARTMIPS) && !defined(CONFIG_CPU_MIPSR6)
                 LONG_S  v1, PT_HI(sp)
                 mflo    v1
 #endif
-                LONG_S  $13, PT_R13(sp)
-                LONG_S  $14, PT_R14(sp)
-                LONG_S  $15, PT_R15(sp)
-                LONG_S  $24, PT_R24(sp)
+                cfi_st  $13, PT_R13, \docfi
+                cfi_st  $14, PT_R14, \docfi
+                cfi_st  $15, PT_R15, \docfi
+                cfi_st  $24, PT_R24, \docfi
 #if !defined(CONFIG_CPU_HAS_SMARTMIPS) && !defined(CONFIG_CPU_MIPSR6)
                 LONG_S  v1, PT_LO(sp)
 #endif
@@ -71,16 +94,16 @@
 #endif
                 .endm
 
-                .macro  SAVE_STATIC
-                LONG_S  $16, PT_R16(sp)
-                LONG_S  $17, PT_R17(sp)
-                LONG_S  $18, PT_R18(sp)
-                LONG_S  $19, PT_R19(sp)
-                LONG_S  $20, PT_R20(sp)
-                LONG_S  $21, PT_R21(sp)
-                LONG_S  $22, PT_R22(sp)
-                LONG_S  $23, PT_R23(sp)
-                LONG_S  $30, PT_R30(sp)
+                .macro  SAVE_STATIC docfi=0
+                cfi_st  $16, PT_R16, \docfi
+                cfi_st  $17, PT_R17, \docfi
+                cfi_st  $18, PT_R18, \docfi
+                cfi_st  $19, PT_R19, \docfi
+                cfi_st  $20, PT_R20, \docfi
+                cfi_st  $21, PT_R21, \docfi
+                cfi_st  $22, PT_R22, \docfi
+                cfi_st  $23, PT_R23, \docfi
+                cfi_st  $30, PT_R30, \docfi
                 .endm
 
 /*
@@ -168,7 +191,7 @@
                 .endm
 #endif
 
-                .macro  SAVE_SOME
+                .macro  SAVE_SOME docfi=0
                 .set    push
                 .set    noat
                 .set    reorder
@@ -203,8 +226,11 @@
 #endif
                 .set    reorder
                  move   k0, sp
+                .if \docfi
+                .cfi_register sp, k0
+                .endif
                 /* Called from user mode, new stack. */
-                get_saved_sp
+                get_saved_sp docfi=\docfi tosp=1
 8:
 #ifdef CONFIG_CPU_DADDI_WORKAROUNDS
                 .set    at=k1
@@ -213,8 +239,12 @@
 #ifdef CONFIG_CPU_DADDI_WORKAROUNDS
                 .set    noat
 #endif
-                LONG_S  k0, PT_R29(sp)
-                LONG_S  $3, PT_R3(sp)
+                .if \docfi
+                .cfi_def_cfa sp,0
+                .endif
+                cfi_st  k0, PT_R29, \docfi
+                cfi_rel_offset  sp, PT_R29, \docfi
+                cfi_st  v1, PT_R3, \docfi
                 /*
                  * You might think that you don't need to save $0,
                  * but the FPU emulator and gdb remote debug stub
@@ -222,23 +252,26 @@
                  */
                 LONG_S  $0, PT_R0(sp)
                 mfc0    v1, CP0_STATUS
-                LONG_S  $2, PT_R2(sp)
+                cfi_st  v0, PT_R2, \docfi
                 LONG_S  v1, PT_STATUS(sp)
-                LONG_S  $4, PT_R4(sp)
+                cfi_st  $4, PT_R4, \docfi
                 mfc0    v1, CP0_CAUSE
-                LONG_S  $5, PT_R5(sp)
+                cfi_st  $5, PT_R5, \docfi
                 LONG_S  v1, PT_CAUSE(sp)
-                LONG_S  $6, PT_R6(sp)
-                LONG_S  ra, PT_R31(sp)
+                cfi_st  $6, PT_R6, \docfi
+                cfi_st  ra, PT_R31, \docfi
                 MFC0    ra, CP0_EPC
-                LONG_S  $7, PT_R7(sp)
+                cfi_st  $7, PT_R7, \docfi
 #ifdef CONFIG_64BIT
-                LONG_S  $8, PT_R8(sp)
-                LONG_S  $9, PT_R9(sp)
+                cfi_st  $8, PT_R8, \docfi
+                cfi_st  $9, PT_R9, \docfi
 #endif
                 LONG_S  ra, PT_EPC(sp)
-                LONG_S  $25, PT_R25(sp)
-                LONG_S  $28, PT_R28(sp)
+                .if \docfi
+                .cfi_rel_offset ra, PT_EPC
+                .endif
+                cfi_st  $25, PT_R25, \docfi
+                cfi_st  $28, PT_R28, \docfi
 
                 /* Set thread_info if we're coming from user mode */
                 mfc0    k0, CP0_STATUS
@@ -255,21 +288,21 @@
                 .set    pop
                 .endm
 
-                .macro  SAVE_ALL
-                SAVE_SOME
-                SAVE_AT
-                SAVE_TEMP
-                SAVE_STATIC
+                .macro  SAVE_ALL docfi=0
+                SAVE_SOME \docfi
+                SAVE_AT \docfi
+                SAVE_TEMP \docfi
+                SAVE_STATIC \docfi
                 .endm
 
-                .macro  RESTORE_AT
+                .macro  RESTORE_AT docfi=0
                 .set    push
                 .set    noat
-                LONG_L  $1,  PT_R1(sp)
+                cfi_ld  $1, PT_R1, \docfi
                 .set    pop
                 .endm
 
-                .macro  RESTORE_TEMP
+                .macro  RESTORE_TEMP docfi=0
 #ifdef CONFIG_CPU_CAVIUM_OCTEON
                 /* Restore the Octeon multiplier state */
                 jal     octeon_mult_restore
@@ -288,33 +321,37 @@
                 mthi    $24
 #endif
 #ifdef CONFIG_32BIT
-                LONG_L  $8, PT_R8(sp)
-                LONG_L  $9, PT_R9(sp)
+                cfi_ld  $8, PT_R8, \docfi
+                cfi_ld  $9, PT_R9, \docfi
 #endif
-                LONG_L  $10, PT_R10(sp)
-                LONG_L  $11, PT_R11(sp)
-                LONG_L  $12, PT_R12(sp)
-                LONG_L  $13, PT_R13(sp)
-                LONG_L  $14, PT_R14(sp)
-                LONG_L  $15, PT_R15(sp)
-                LONG_L  $24, PT_R24(sp)
+                cfi_ld  $10, PT_R10, \docfi
+                cfi_ld  $11, PT_R11, \docfi
+                cfi_ld  $12, PT_R12, \docfi
+                cfi_ld  $13, PT_R13, \docfi
+                cfi_ld  $14, PT_R14, \docfi
+                cfi_ld  $15, PT_R15, \docfi
+                cfi_ld  $24, PT_R24, \docfi
                 .endm
 
-                .macro  RESTORE_STATIC
-                LONG_L  $16, PT_R16(sp)
-                LONG_L  $17, PT_R17(sp)
-                LONG_L  $18, PT_R18(sp)
-                LONG_L  $19, PT_R19(sp)
-                LONG_L  $20, PT_R20(sp)
-                LONG_L  $21, PT_R21(sp)
-                LONG_L  $22, PT_R22(sp)
-                LONG_L  $23, PT_R23(sp)
-                LONG_L  $30, PT_R30(sp)
+                .macro  RESTORE_STATIC docfi=0
+                cfi_ld  $16, PT_R16, \docfi
+                cfi_ld  $17, PT_R17, \docfi
+                cfi_ld  $18, PT_R18, \docfi
+                cfi_ld  $19, PT_R19, \docfi
+                cfi_ld  $20, PT_R20, \docfi
+                cfi_ld  $21, PT_R21, \docfi
+                cfi_ld  $22, PT_R22, \docfi
+                cfi_ld  $23, PT_R23, \docfi
+                cfi_ld  $30, PT_R30, \docfi
+                .endm
+
+                .macro  RESTORE_SP docfi=0
+                cfi_ld  sp, PT_R29, \docfi
                 .endm
 
 #if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
 
-                .macro  RESTORE_SOME
+                .macro  RESTORE_SOME docfi=0
                 .set    push
                 .set    reorder
                 .set    noat
@@ -329,30 +366,30 @@
                 and     v0, v1
                 or      v0, a0
                 mtc0    v0, CP0_STATUS
-                LONG_L  $31, PT_R31(sp)
-                LONG_L  $28, PT_R28(sp)
-                LONG_L  $25, PT_R25(sp)
-                LONG_L  $7,  PT_R7(sp)
-                LONG_L  $6,  PT_R6(sp)
-                LONG_L  $5,  PT_R5(sp)
-                LONG_L  $4,  PT_R4(sp)
-                LONG_L  $3,  PT_R3(sp)
-                LONG_L  $2,  PT_R2(sp)
+                cfi_ld  $31, PT_R31, \docfi
+                cfi_ld  $28, PT_R28, \docfi
+                cfi_ld  $25, PT_R25, \docfi
+                cfi_ld  $7,  PT_R7, \docfi
+                cfi_ld  $6,  PT_R6, \docfi
+                cfi_ld  $5,  PT_R5, \docfi
+                cfi_ld  $4,  PT_R4, \docfi
+                cfi_ld  $3,  PT_R3, \docfi
+                cfi_ld  $2,  PT_R2, \docfi
                 .set    pop
                 .endm
 
-                .macro  RESTORE_SP_AND_RET
+                .macro  RESTORE_SP_AND_RET docfi=0
                 .set    push
                 .set    noreorder
                 LONG_L  k0, PT_EPC(sp)
-                LONG_L  sp, PT_R29(sp)
+                RESTORE_SP \docfi
                 jr      k0
                  rfe
                 .set    pop
                 .endm
 
 #else
-                .macro  RESTORE_SOME
+                .macro  RESTORE_SOME docfi=0
                 .set    push
                 .set    reorder
                 .set    noat
@@ -369,24 +406,24 @@
                 mtc0    v0, CP0_STATUS
                 LONG_L  v1, PT_EPC(sp)
                 MTC0    v1, CP0_EPC
-                LONG_L  $31, PT_R31(sp)
-                LONG_L  $28, PT_R28(sp)
-                LONG_L  $25, PT_R25(sp)
+                cfi_ld  $31, PT_R31, \docfi
+                cfi_ld  $28, PT_R28, \docfi
+                cfi_ld  $25, PT_R25, \docfi
 #ifdef CONFIG_64BIT
-                LONG_L  $8, PT_R8(sp)
-                LONG_L  $9, PT_R9(sp)
+                cfi_ld  $8, PT_R8, \docfi
+                cfi_ld  $9, PT_R9, \docfi
 #endif
-                LONG_L  $7,  PT_R7(sp)
-                LONG_L  $6,  PT_R6(sp)
-                LONG_L  $5,  PT_R5(sp)
-                LONG_L  $4,  PT_R4(sp)
-                LONG_L  $3,  PT_R3(sp)
-                LONG_L  $2,  PT_R2(sp)
+                cfi_ld  $7,  PT_R7, \docfi
+                cfi_ld  $6,  PT_R6, \docfi
+                cfi_ld  $5,  PT_R5, \docfi
+                cfi_ld  $4,  PT_R4, \docfi
+                cfi_ld  $3,  PT_R3, \docfi
+                cfi_ld  $2,  PT_R2, \docfi
                 .set    pop
                 .endm
 
-                .macro  RESTORE_SP_AND_RET
-                LONG_L  sp, PT_R29(sp)
+                .macro  RESTORE_SP_AND_RET docfi=0
+                RESTORE_SP \docfi
 #ifdef CONFIG_CPU_MIPSR6
                 eretnc
 #else
@@ -398,16 +435,12 @@
 
 #endif
 
-                .macro  RESTORE_SP
-                LONG_L  sp, PT_R29(sp)
-                .endm
-
-                .macro  RESTORE_ALL
-                RESTORE_TEMP
-                RESTORE_STATIC
-                RESTORE_AT
-                RESTORE_SOME
-                RESTORE_SP
+                .macro  RESTORE_ALL docfi=0
+                RESTORE_TEMP \docfi
+                RESTORE_STATIC \docfi
+                RESTORE_AT \docfi
+                RESTORE_SOME \docfi
+                RESTORE_SP \docfi
                 .endm
 
 /*
diff --git a/arch/mips/kernel/genex.S b/arch/mips/kernel/genex.S
index ae810da4d499..37b9383eacd3 100644
--- a/arch/mips/kernel/genex.S
+++ b/arch/mips/kernel/genex.S
@@ -150,6 +150,7 @@ LEAF(__r4k_wait)
         .align  5
 BUILD_ROLLBACK_PROLOGUE handle_int
 NESTED(handle_int, PT_SIZE, sp)
+        .cfi_signal_frame
 #ifdef CONFIG_TRACE_IRQFLAGS
         /*
          * Check to see if the interrupted code has just disabled
@@ -181,7 +182,7 @@ NESTED(handle_int, PT_SIZE, sp)
 1:
         .set pop
 #endif
-        SAVE_ALL
+        SAVE_ALL docfi=1
         CLI
         TRACE_IRQS_OFF
 
@@ -269,8 +270,8 @@ NESTED(except_vec_ejtag_debug, 0, sp)
  */
 BUILD_ROLLBACK_PROLOGUE except_vec_vi
 NESTED(except_vec_vi, 0, sp)
-        SAVE_SOME
-        SAVE_AT
+        SAVE_SOME docfi=1
+        SAVE_AT docfi=1
         .set    push
         .set    noreorder
         PTR_LA  v1, except_vec_vi_handler
@@ -396,6 +397,7 @@ NESTED(except_vec_nmi, 0, sp)
         __FINIT
 
 NESTED(nmi_handler, PT_SIZE, sp)
+        .cfi_signal_frame
         .set    push
         .set    noat
         /*
@@ -478,6 +480,7 @@ NESTED(nmi_handler, PT_SIZE, sp)
         .macro  __BUILD_HANDLER exception handler clear verbose ext
         .align  5
         NESTED(handle_\exception, PT_SIZE, sp)
+        .cfi_signal_frame
         .set    noat
         SAVE_ALL
         FEXPORT(handle_\exception\ext)
@@ -485,8 +488,8 @@ NESTED(nmi_handler, PT_SIZE, sp)
         .set    at
         __BUILD_\verbose \exception
         move    a0, sp
-        PTR_LA  ra, ret_from_exception
-        j       do_\handler
+        jal     do_\handler
+        j       ret_from_exception
         END(handle_\exception)
         .endm
 
diff --git a/arch/mips/mm/tlbex-fault.S b/arch/mips/mm/tlbex-fault.S
index 318855eb5f80..77db401fc620 100644
--- a/arch/mips/mm/tlbex-fault.S
+++ b/arch/mips/mm/tlbex-fault.S
@@ -12,14 +12,15 @@
 
         .macro tlb_do_page_fault, write
         NESTED(tlb_do_page_fault_\write, PT_SIZE, sp)
-        SAVE_ALL
+        .cfi_signal_frame
+        SAVE_ALL docfi=1
         MFC0    a2, CP0_BADVADDR
         KMODE
         move    a0, sp
         REG_S   a2, PT_BVADDR(sp)
         li      a1, \write
-        PTR_LA  ra, ret_from_exception
-        j       do_page_fault
+        jal     do_page_fault
+        j       ret_from_exception
         END(tlb_do_page_fault_\write)
         .endm
 
diff --git a/arch/mips/vdso/sigreturn.S b/arch/mips/vdso/sigreturn.S
index 715bf5993529..30c6219912ac 100644
--- a/arch/mips/vdso/sigreturn.S
+++ b/arch/mips/vdso/sigreturn.S
@@ -19,31 +19,21 @@
         .cfi_sections   .debug_frame
 
 LEAF(__vdso_rt_sigreturn)
-        .cfi_startproc
-        .frame  sp, 0, ra
-        .mask   0x00000000, 0
-        .fmask  0x00000000, 0
         .cfi_signal_frame
 
         li      v0, __NR_rt_sigreturn
         syscall
 
-        .cfi_endproc
         END(__vdso_rt_sigreturn)
 
 #if _MIPS_SIM == _MIPS_SIM_ABI32
 
 LEAF(__vdso_sigreturn)
-        .cfi_startproc
-        .frame  sp, 0, ra
-        .mask   0x00000000, 0
-        .fmask  0x00000000, 0
         .cfi_signal_frame
 
         li      v0, __NR_sigreturn
         syscall
 
-        .cfi_endproc
         END(__vdso_sigreturn)
 
 #endif