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s390/vdso: revise CFI annotations of vDSO functions 

Revise and add CFI CFA and register rule annotations to the vDSO
functions for proper stack unwinding and debugging.

Because glibc might call the vDSO in special ways, the vDSO code
does not rely on a stack frame created by the caller.  The TOD clock
value can be therefore not stored in the pre-allocated stack area
and additional stack space is required.
To correctly annotate these situations with CFI, the .cfi_val_offset
directive is required to create relative offsets on the value of the
stack register %r15.  Because the .cfi_val_offset directive is
available with recent GNU assembler versions only, additional checks
are necessary.

Note that if the vDSO is assembled with an older assembler version,
stack unwinding and debugging from within the vDSO code might not
be possible.

Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Hendrik Brueckner 2017-11-20 11:46:13 +01:00 committed by Martin Schwidefsky
parent bc3703f21c
commit 7bceec4e58
10 changed files with 69 additions and 18 deletions
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7
arch/s390/Makefile
View File

@ -88,10 +88,13 @@ KBUILD_CFLAGS += -DCC_USING_HOTPATCH
endif
endif
# Test CFI features of binutils
cfi := $(call as-instr,.cfi_startproc\n.cfi_val_offset 15$(comma)-160\n.cfi_endproc,-DCONFIG_AS_CFI_VAL_OFFSET=1)
KBUILD_CFLAGS += -mbackchain -msoft-float $(cflags-y)
KBUILD_CFLAGS += -pipe -fno-strength-reduce -Wno-sign-compare
KBUILD_CFLAGS += -fno-asynchronous-unwind-tables
KBUILD_AFLAGS += $(aflags-y)
KBUILD_CFLAGS += -fno-asynchronous-unwind-tables $(cfi)
KBUILD_AFLAGS += $(aflags-y) $(cfi)
OBJCOPYFLAGS := -O binary

12
arch/s390/include/asm/dwarf.h
View File

@ -4,6 +4,18 @@
#ifdef __ASSEMBLY__
#define CFI_STARTPROC .cfi_startproc
#define CFI_ENDPROC .cfi_endproc
#define CFI_DEF_CFA_OFFSET .cfi_def_cfa_offset
#define CFI_ADJUST_CFA_OFFSET .cfi_adjust_cfa_offset
#define CFI_RESTORE .cfi_restore
#ifdef CONFIG_AS_CFI_VAL_OFFSET
#define CFI_VAL_OFFSET .cfi_val_offset
#else
#define CFI_VAL_OFFSET #
#endif
#ifndef BUILD_VDSO
/*
* Emit CFI data in .debug_frame sections and not in .eh_frame

4
arch/s390/kernel/vdso32/clock_getres.S
View File

@ -16,7 +16,7 @@
.globl __kernel_clock_getres
.type __kernel_clock_getres,@function
__kernel_clock_getres:
.cfi_startproc
CFI_STARTPROC
basr %r1,0
la %r1,4f-.(%r1)
chi %r2,__CLOCK_REALTIME
@ -38,7 +38,7 @@ __kernel_clock_getres:
3: lhi %r1,__NR_clock_getres /* fallback to svc */
svc 0
br %r14
CFI_ENDPROC
4: .long __CLOCK_REALTIME_RES
5: .long __CLOCK_COARSE_RES
.cfi_endproc
.size __kernel_clock_getres,.-__kernel_clock_getres

16
arch/s390/kernel/vdso32/clock_gettime.S
View File

@ -16,8 +16,10 @@
.globl __kernel_clock_gettime
.type __kernel_clock_gettime,@function
__kernel_clock_gettime:
.cfi_startproc
CFI_STARTPROC
ahi %r15,-16
CFI_DEF_CFA_OFFSET 176
CFI_VAL_OFFSET 15, -160
basr %r5,0
0: al %r5,21f-0b(%r5) /* get &_vdso_data */
chi %r2,__CLOCK_REALTIME_COARSE
@ -70,9 +72,13 @@ __kernel_clock_gettime:
st %r1,4(%r3) /* store tp->tv_nsec */
lhi %r2,0
ahi %r15,16
CFI_DEF_CFA_OFFSET 160
CFI_RESTORE 15
br %r14
/* CLOCK_MONOTONIC_COARSE */
CFI_DEF_CFA_OFFSET 176
CFI_VAL_OFFSET 15, -160
9: l %r4,__VDSO_UPD_COUNT+4(%r5) /* load update counter */
tml %r4,0x0001 /* pending update ? loop */
jnz 9b
@ -152,15 +158,21 @@ __kernel_clock_gettime:
st %r1,4(%r3) /* store tp->tv_nsec */
lhi %r2,0
ahi %r15,16
CFI_DEF_CFA_OFFSET 160
CFI_RESTORE 15
br %r14
/* Fallback to system call */
CFI_DEF_CFA_OFFSET 176
CFI_VAL_OFFSET 15, -160
19: lhi %r1,__NR_clock_gettime
svc 0
ahi %r15,16
CFI_DEF_CFA_OFFSET 160
CFI_RESTORE 15
br %r14
CFI_ENDPROC
20: .long 1000000000
21: .long _vdso_data - 0b
.cfi_endproc
.size __kernel_clock_gettime,.-__kernel_clock_gettime

4
arch/s390/kernel/vdso32/getcpu.S
View File

@ -15,7 +15,7 @@
.globl __kernel_getcpu
.type __kernel_getcpu,@function
__kernel_getcpu:
.cfi_startproc
CFI_STARTPROC
la %r4,0
sacf 256
l %r5,__VDSO_CPU_NR(%r4)
@ -29,5 +29,5 @@ __kernel_getcpu:
st %r4,0(%r3)
3: lhi %r2,0
br %r14
.cfi_endproc
CFI_ENDPROC
.size __kernel_getcpu,.-__kernel_getcpu

8
arch/s390/kernel/vdso32/gettimeofday.S
View File

@ -16,8 +16,10 @@
.globl __kernel_gettimeofday
.type __kernel_gettimeofday,@function
__kernel_gettimeofday:
.cfi_startproc
CFI_STARTPROC
ahi %r15,-16
CFI_ADJUST_CFA_OFFSET 16
CFI_VAL_OFFSET 15, -160
basr %r5,0
0: al %r5,13f-0b(%r5) /* get &_vdso_data */
1: ltr %r3,%r3 /* check if tz is NULL */
@ -90,9 +92,11 @@ __kernel_gettimeofday:
st %r0,4(%r2) /* store tv->tv_usec */
10: slr %r2,%r2
ahi %r15,16
CFI_ADJUST_CFA_OFFSET -16
CFI_RESTORE 15
br %r14
CFI_ENDPROC
11: .long 1000000000
12: .long 274877907
13: .long _vdso_data - 0b
.cfi_endproc
.size __kernel_gettimeofday,.-__kernel_gettimeofday

4
arch/s390/kernel/vdso64/clock_getres.S
View File

@ -16,7 +16,7 @@
.globl __kernel_clock_getres
.type __kernel_clock_getres,@function
__kernel_clock_getres:
.cfi_startproc
CFI_STARTPROC
larl %r1,4f
cghi %r2,__CLOCK_REALTIME_COARSE
je 0f
@ -44,7 +44,7 @@ __kernel_clock_getres:
2: lghi %r1,__NR_clock_getres /* fallback to svc */
svc 0
br %r14
CFI_ENDPROC
3: .quad __CLOCK_REALTIME_RES
4: .quad __CLOCK_COARSE_RES
.cfi_endproc
.size __kernel_clock_getres,.-__kernel_clock_getres

20
arch/s390/kernel/vdso64/clock_gettime.S
View File

@ -16,8 +16,10 @@
.globl __kernel_clock_gettime
.type __kernel_clock_gettime,@function
__kernel_clock_gettime:
.cfi_startproc
CFI_STARTPROC
aghi %r15,-16
CFI_DEF_CFA_OFFSET 176
CFI_VAL_OFFSET 15, -160
larl %r5,_vdso_data
cghi %r2,__CLOCK_REALTIME_COARSE
je 4f
@ -54,9 +56,13 @@ __kernel_clock_gettime:
stg %r1,8(%r3) /* store tp->tv_nsec */
lghi %r2,0
aghi %r15,16
CFI_DEF_CFA_OFFSET 160
CFI_RESTORE 15
br %r14
/* CLOCK_MONOTONIC_COARSE */
CFI_DEF_CFA_OFFSET 176
CFI_VAL_OFFSET 15, -160
3: lg %r4,__VDSO_UPD_COUNT(%r5) /* load update counter */
tmll %r4,0x0001 /* pending update ? loop */
jnz 3b
@ -109,9 +115,13 @@ __kernel_clock_gettime:
stg %r1,8(%r3) /* store tp->tv_nsec */
lghi %r2,0
aghi %r15,16
CFI_DEF_CFA_OFFSET 160
CFI_RESTORE 15
br %r14
/* CPUCLOCK_VIRT for this thread */
CFI_DEF_CFA_OFFSET 176
CFI_VAL_OFFSET 15, -160
9: lghi %r4,0
icm %r0,15,__VDSO_ECTG_OK(%r5)
jz 12f
@ -132,15 +142,21 @@ __kernel_clock_gettime:
stg %r4,8(%r3)
lghi %r2,0
aghi %r15,16
CFI_DEF_CFA_OFFSET 160
CFI_RESTORE 15
br %r14
/* Fallback to system call */
CFI_DEF_CFA_OFFSET 176
CFI_VAL_OFFSET 15, -160
12: lghi %r1,__NR_clock_gettime
svc 0
aghi %r15,16
CFI_DEF_CFA_OFFSET 160
CFI_RESTORE 15
br %r14
CFI_ENDPROC
13: .quad 1000000000
14: .quad 19342813113834067
.cfi_endproc
.size __kernel_clock_gettime,.-__kernel_clock_gettime

4
arch/s390/kernel/vdso64/getcpu.S
View File

@ -15,7 +15,7 @@
.globl __kernel_getcpu
.type __kernel_getcpu,@function
__kernel_getcpu:
.cfi_startproc
CFI_STARTPROC
la %r4,0
sacf 256
l %r5,__VDSO_CPU_NR(%r4)
@ -29,5 +29,5 @@ __kernel_getcpu:
st %r4,0(%r3)
3: lghi %r2,0
br %r14
.cfi_endproc
CFI_ENDPROC
.size __kernel_getcpu,.-__kernel_getcpu

8
arch/s390/kernel/vdso64/gettimeofday.S
View File

@ -16,8 +16,10 @@
.globl __kernel_gettimeofday
.type __kernel_gettimeofday,@function
__kernel_gettimeofday:
.cfi_startproc
CFI_STARTPROC
aghi %r15,-16
CFI_ADJUST_CFA_OFFSET 16
CFI_VAL_OFFSET 15, -160
larl %r5,_vdso_data
0: ltgr %r3,%r3 /* check if tz is NULL */
je 1f
@ -59,8 +61,10 @@ __kernel_gettimeofday:
stg %r0,8(%r2) /* store tv->tv_usec */
4: lghi %r2,0
aghi %r15,16
CFI_ADJUST_CFA_OFFSET -16
CFI_RESTORE 15
br %r14
CFI_ENDPROC
5: .quad 1000000000
.long 274877907
.cfi_endproc
.size __kernel_gettimeofday,.-__kernel_gettimeofday