https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64012
Bug ID: 64012
Summary: GCC-4.9.2 option -fcaller-saves in -O2
Product: gcc
Version: 4.9.2
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: airbak.li at huawei dot com
A cross toolchain build by GCC-4.9.2, when I use this toolchain to compile
kernel-3.4.35 with option -O2, it always crash when system power up.
(CPU : armv-7 cortex-a9)
-----------Crash log------------------------------
Unable to handle kernel paging request at virtual address ffffffff
pgd = c0004000
[ffffffff] *pgd=85ffe821, *pte=00000000, *ppte=00000000
Internal error: Oops: 17 [#1] SMP ARM
Modules linked in:
CPU: 1 Not tainted (3.4.35_hi3535 #27)
PC is at kmem_cache_alloc+0x54/0x130
LR is at con_insert_unipair+0xc0/0x10c
pc : [<c00a5764>] lr : [<c028447c>] psr: a0000013
sp : c5831e60 ip : c05b27d8 fp : c5831e94
r10: 00000263 r9 : 00000003 r8 : 0000005f
r7 : 0000005f r6 : 000000d0 r5 : c5802200 r4 : ffffffff
r3 : 00000000 r2 : c5830000 r1 : c05a69e0 r0 : 0011e000
Flags: NzCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment kernel
Control: 10c53c7d Table: 8000404a DAC: 00000015
-------------Assembler code-------------------------
c00a5710 <kmem_cache_alloc>:
c00a5710: e1a0c00d mov ip, sp
c00a5714: e92ddff0 push {r4, r5, r6, r7, r8, r9, sl, fp, ip, lr, pc}
c00a5718: e24cb004 sub fp, ip, #4
c00a571c: e24dd00c sub sp, sp, #12
c00a5720: e1a0300d mov r3, sp
c00a5724: e3c32d7f bic r2, r3, #8128 ; 0x1fc0
c00a5728: e302c7d8 movw ip, #10200 ; 0x27d8
c00a572c: e3c2203f bic r2, r2, #63 ; 0x3f
c00a5730: e34cc05b movt ip, #49243 ; 0xc05b
c00a5734: e1a05000 mov r5, r0
c00a5738: e1a06001 mov r6, r1
c00a573c: e50be030 str lr, [fp, #-48] ; 0x30
c00a5740: e5923014 ldr r3, [r2, #20]
c00a5744: e5951000 ldr r1, [r5]
c00a5748: e79c0103 ldr r0, [ip, r3, lsl #2]
c00a574c: e0813000 add r3, r1, r0
c00a5750: e593a004 ldr sl, [r3, #4]
c00a5754: e7914000 ldr r4, [r1, r0]
c00a5758: e3540000 cmp r4, #0
c00a575c: 0a000026 beq c00a57fc <kmem_cache_alloc+0xec>
c00a5760: e5953014 ldr r3, [r5, #20]
c00a5764: e7949003 ldr r9, [r4, r3] --->r4 is ffffffff
c00a5768: e10f8000 mrs r8, CPSR
----------------------------------------------
When I compile kernel with "-O1" or "-O2 -fno-caller-saves", it is ok, no
crash.
(GCC-4.8 not have this problem)
Question:
1. Please tell me about option "-fcaller-saves" in GCC-4.9.2. Is it different
from GCC-4.8?
2. The error happen in code
"con_insert_unipair()->kmem_cache_alloc()->slab_alloc()", file path is
"linux-3.4.35\mm\slub.c".
What codes will "-fcaller-saves" optimize? Please give me some samples.
3."-fcaller-saves" may be not the root cause.
Generally, we use -O2 include "-fcaller-saves", we want to keep
"-fcaller-saves", please help me to solve it.
