[ARM] Add ability to dump exception stacks to kernel backtraces
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Russell King
committed by
Russell King
Russell King
parent
46fcc86dd7
commit
7ab3f8d595
@@ -17,8 +17,8 @@
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@ fp is 0 or stack frame
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#define frame r4
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#define next r5
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#define save r6
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#define sv_fp r5
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#define sv_pc r6
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#define mask r7
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#define offset r8
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@@ -31,108 +31,106 @@ ENTRY(c_backtrace)
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#if !defined(CONFIG_FRAME_POINTER) || !defined(CONFIG_PRINTK)
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mov pc, lr
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#else
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stmfd sp!, {r4 - r8, lr} @ Save an extra register so we have a location...
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tst r1, #0x10 @ 26 or 32-bit?
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moveq mask, #0xfc000003
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movne mask, #0
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tst mask, r0
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movne r0, #0
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movs frame, r0
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1: moveq r0, #-2
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ldmeqfd sp!, {r4 - r8, pc}
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movs frame, r0 @ if frame pointer is zero
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beq no_frame @ we have no stack frames
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2: stmfd sp!, {pc} @ calculate offset of PC in STMIA instruction
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ldr r0, [sp], #4
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adr r1, 2b - 4
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tst r1, #0x10 @ 26 or 32-bit mode?
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moveq mask, #0xfc000003 @ mask for 26-bit
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movne mask, #0 @ mask for 32-bit
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1: stmfd sp!, {pc} @ calculate offset of PC stored
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ldr r0, [sp], #4 @ by stmfd for this CPU
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adr r1, 1b
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sub offset, r0, r1
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3: tst frame, mask @ Check for address exceptions...
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bne 1b
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/*
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* Stack frame layout:
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* optionally saved caller registers (r4 - r10)
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* saved fp
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* saved sp
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* saved lr
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* frame => saved pc
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* optionally saved arguments (r0 - r3)
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* saved sp => <next word>
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*
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* Functions start with the following code sequence:
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* mov ip, sp
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* stmfd sp!, {r0 - r3} (optional)
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* corrected pc => stmfd sp!, {..., fp, ip, lr, pc}
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*/
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for_each_frame: tst frame, mask @ Check for address exceptions
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bne no_frame
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1001: ldr next, [frame, #-12] @ get fp
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1002: ldr r2, [frame, #-4] @ get lr
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1003: ldr r3, [frame, #0] @ get pc
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sub save, r3, offset @ Correct PC for prefetching
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bic save, save, mask
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1004: ldr r1, [save, #0] @ get instruction at function
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mov r1, r1, lsr #10
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ldr r3, .Ldsi+4
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teq r1, r3
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subeq save, save, #4
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mov r0, save
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bic r1, r2, mask
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1001: ldr sv_pc, [frame, #0] @ get saved pc
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1002: ldr sv_fp, [frame, #-12] @ get saved fp
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sub sv_pc, sv_pc, offset @ Correct PC for prefetching
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bic sv_pc, sv_pc, mask @ mask PC/LR for the mode
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1003: ldr r2, [sv_pc, #-4] @ if stmfd sp!, {args} exists,
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ldr r3, .Ldsi+4 @ adjust saved 'pc' back one
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teq r3, r2, lsr #10 @ instruction
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subne r0, sv_pc, #4 @ allow for mov
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subeq r0, sv_pc, #8 @ allow for mov + stmia
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ldr r1, [frame, #-4] @ get saved lr
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mov r2, frame
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bic r1, r1, mask @ mask PC/LR for the mode
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bl dump_backtrace_entry
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ldr r0, [frame, #-8] @ get sp
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sub r0, r0, #4
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1005: ldr r1, [save, #4] @ get instruction at function+4
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mov r3, r1, lsr #10
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ldr r2, .Ldsi+4
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teq r3, r2 @ Check for stmia sp!, {args}
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addeq save, save, #4 @ next instruction
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bleq .Ldumpstm
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ldr r1, [sv_pc, #-4] @ if stmfd sp!, {args} exists,
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ldr r3, .Ldsi+4
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teq r3, r1, lsr #10
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ldreq r0, [frame, #-8] @ get sp
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subeq r0, r0, #4 @ point at the last arg
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bleq .Ldumpstm @ dump saved registers
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sub r0, frame, #16
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1006: ldr r1, [save, #4] @ Get 'stmia sp!, {rlist, fp, ip, lr, pc}' instruction
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mov r3, r1, lsr #10
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ldr r2, .Ldsi
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teq r3, r2
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bleq .Ldumpstm
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1004: ldr r1, [sv_pc, #0] @ if stmfd sp!, {..., fp, ip, lr, pc}
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ldr r3, .Ldsi @ instruction exists,
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teq r3, r1, lsr #10
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subeq r0, frame, #16
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bleq .Ldumpstm @ dump saved registers
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/*
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* A zero next framepointer means we're done.
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*/
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teq next, #0
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ldmeqfd sp!, {r4 - r8, pc}
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teq sv_fp, #0 @ zero saved fp means
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beq no_frame @ no further frames
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/*
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* The next framepointer must be above the
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* current framepointer.
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*/
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cmp next, frame
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mov frame, next
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bhi 3b
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b 1007f
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cmp sv_fp, frame @ next frame must be
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mov frame, sv_fp @ above the current frame
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bhi for_each_frame
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/*
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* Fixup for LDMDB. Note that this must not be in the fixup section.
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*/
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1007: ldr r0, =.Lbad
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1006: adr r0, .Lbad
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mov r1, frame
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bl printk
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ldmfd sp!, {r4 - r8, pc}
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.ltorg
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no_frame: ldmfd sp!, {r4 - r8, pc}
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.section __ex_table,"a"
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.align 3
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.long 1001b, 1007b
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.long 1002b, 1007b
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.long 1003b, 1007b
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.long 1004b, 1007b
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.long 1005b, 1007b
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.long 1006b, 1007b
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.long 1001b, 1006b
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.long 1002b, 1006b
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.long 1003b, 1006b
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.long 1004b, 1006b
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.previous
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#define instr r4
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#define reg r5
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#define stack r6
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.Ldumpstm: stmfd sp!, {instr, reg, stack, r7, r8, lr}
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.Ldumpstm: stmfd sp!, {instr, reg, stack, r7, lr}
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mov stack, r0
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mov instr, r1
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mov reg, #9
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mov reg, #10
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mov r7, #0
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1: mov r3, #1
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tst instr, r3, lsl reg
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beq 2f
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add r7, r7, #1
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teq r7, #4
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moveq r7, #0
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moveq r3, #'\n'
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movne r3, #' '
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ldr r2, [stack], #-4
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mov r1, reg
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teq r7, #6
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moveq r7, #1
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moveq r1, #'\n'
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movne r1, #' '
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ldr r3, [stack], #-4
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mov r2, reg
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adr r0, .Lfp
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bl printk
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2: subs reg, reg, #1
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@@ -140,14 +138,13 @@ ENTRY(c_backtrace)
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teq r7, #0
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adrne r0, .Lcr
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blne printk
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mov r0, stack
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ldmfd sp!, {instr, reg, stack, r7, r8, pc}
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ldmfd sp!, {instr, reg, stack, r7, pc}
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.Lfp: .asciz " r%d = %08X%c"
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.Lfp: .asciz "%cr%d:%08x"
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.Lcr: .asciz "\n"
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.Lbad: .asciz "Backtrace aborted due to bad frame pointer <%p>\n"
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.align
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.Ldsi: .word 0x00e92dd8 >> 2
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.word 0x00e92d00 >> 2
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.Ldsi: .word 0xe92dd800 >> 10 @ stmfd sp!, {... fp, ip, lr, pc}
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.word 0xe92d0000 >> 10 @ stmfd sp!, {}
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#endif
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