diff options
| author | Russell King <rmk+kernel@armlinux.org.uk> | 2016-11-15 13:55:59 +0000 |
|---|---|---|
| committer | Russell King <rmk+kernel@armlinux.org.uk> | 2016-11-15 15:25:39 +0000 |
| commit | 24c66dfd569c4744fc43aea638155ad2dc1499d8 (patch) | |
| tree | aafbb0d392b4384411c0027773890cbd7ec77cb8 /arch/arm/lib | |
| parent | 6127d124ee4eb9c39983813cc9803f3654ab7e16 (diff) | |
ARM: fix backtrace
Recent kernels have changed their behaviour to be more inconsistent
when handling printk continuations. With todays kernels, the output
looks sane on the console, but dmesg splits individual printk()s which
do not have the KERN_CONT prefix into separate lines.
Since the assembly code is not trivial to add the KERN_CONT, and we
ideally want to avoid using KERN_CONT (as multiple printk()s can race
between different threads), convert the assembly dumping the register
values to C code, and have the C code build the output a line at a
time before dumping to the console.
This avoids the KERN_CONT issue, and also avoids situations where the
output is intermixed with other console activity.
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Diffstat (limited to 'arch/arm/lib')
| -rw-r--r-- | arch/arm/lib/backtrace.S | 37 |
1 files changed, 3 insertions, 34 deletions
diff --git a/arch/arm/lib/backtrace.S b/arch/arm/lib/backtrace.S index fab5a50503ae..7d7952e5a3b1 100644 --- a/arch/arm/lib/backtrace.S +++ b/arch/arm/lib/backtrace.S @@ -10,6 +10,7 @@ * 27/03/03 Ian Molton Clean up CONFIG_CPU * */ +#include <linux/kern_levels.h> #include <linux/linkage.h> #include <asm/assembler.h> .text @@ -83,13 +84,13 @@ for_each_frame: tst frame, mask @ Check for address exceptions teq r3, r1, lsr #11 ldreq r0, [frame, #-8] @ get sp subeq r0, r0, #4 @ point at the last arg - bleq .Ldumpstm @ dump saved registers + bleq dump_backtrace_stm @ dump saved registers 1004: ldr r1, [sv_pc, #0] @ if stmfd sp!, {..., fp, ip, lr, pc} ldr r3, .Ldsi @ instruction exists, teq r3, r1, lsr #11 subeq r0, frame, #16 - bleq .Ldumpstm @ dump saved registers + bleq dump_backtrace_stm @ dump saved registers teq sv_fp, #0 @ zero saved fp means beq no_frame @ no further frames @@ -112,38 +113,6 @@ ENDPROC(c_backtrace) .long 1004b, 1006b .popsection -#define instr r4 -#define reg r5 -#define stack r6 - -.Ldumpstm: stmfd sp!, {instr, reg, stack, r7, lr} - mov stack, r0 - mov instr, r1 - mov reg, #10 - mov r7, #0 -1: mov r3, #1 - ARM( tst instr, r3, lsl reg ) - THUMB( lsl r3, reg ) - THUMB( tst instr, r3 ) - beq 2f - add r7, r7, #1 - teq r7, #6 - moveq r7, #0 - adr r3, .Lcr - addne r3, r3, #1 @ skip newline - ldr r2, [stack], #-4 - mov r1, reg - adr r0, .Lfp - bl printk -2: subs reg, reg, #1 - bpl 1b - teq r7, #0 - adrne r0, .Lcr - blne printk - ldmfd sp!, {instr, reg, stack, r7, pc} - -.Lfp: .asciz " r%d:%08x%s" -.Lcr: .asciz "\n" .Lbad: .asciz "Backtrace aborted due to bad frame pointer <%p>\n" .align .Ldsi: .word 0xe92dd800 >> 11 @ stmfd sp!, {... fp, ip, lr, pc} |