[PATCH 3/4] mips: Add DWARF unwinding to assembly

From: minyard
Date: Thu Aug 10 2017 - 14:28:25 EST


From: Corey Minyard <cminyard@xxxxxxxxxx>

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@xxxxxxxxxx>
---
arch/mips/Makefile | 4 +
arch/mips/include/asm/asm.h | 3 +
arch/mips/include/asm/stackframe.h | 231 +++++++++++++++++++++----------------
arch/mips/kernel/genex.S | 13 ++-
arch/mips/mm/tlbex-fault.S | 7 +-
arch/mips/vdso/sigreturn.S | 10 --
6 files changed, 151 insertions(+), 117 deletions(-)

diff --git a/arch/mips/Makefile b/arch/mips/Makefile
index 0434362..fb0b6dc 100644
--- a/arch/mips/Makefile
+++ b/arch/mips/Makefile
@@ -286,6 +286,10 @@ 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 859cf70..81fae23 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 d2fb919..5d3563c 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 ae810da..37b9383 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 318855e..77db401 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 715bf59..30c6219 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
--
2.7.4