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>

diff --git a/arch/s390/Makefile b/arch/s390/Makefile
index 494bb9ad5edfb388a6567fa597dbe7e139cb806c..aa37ba79c762e5314bb4b508cc30eb79e040a300 100644 (file)
--- a/arch/s390/Makefile
+++ b/arch/s390/Makefile
@@ -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
 

diff --git a/arch/s390/include/asm/dwarf.h b/arch/s390/include/asm/dwarf.h
index dffdb81e534f836f5361d2a92dd3e6b1a8c5e575..4f21ae561e4ddc7af7bc7a21f848f0fe4315ab59 100644 (file)
--- a/arch/s390/include/asm/dwarf.h
+++ b/arch/s390/include/asm/dwarf.h
@@ -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

diff --git a/arch/s390/kernel/vdso32/clock_getres.S b/arch/s390/kernel/vdso32/clock_getres.S
index 6aeddf8e4bc732bc1f0a355c382285019e8daba8..eaf9cf1417f675818e46a9ddf575ba13428b5176 100644 (file)
--- a/arch/s390/kernel/vdso32/clock_getres.S
+++ b/arch/s390/kernel/vdso32/clock_getres.S
@@ -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

diff --git a/arch/s390/kernel/vdso32/clock_gettime.S b/arch/s390/kernel/vdso32/clock_gettime.S
index d0ac32c413e29a7ec0af766f31c8e25532a81673..a9418bf975db5a32db1c88b07d59f71454ce550b 100644 (file)
--- a/arch/s390/kernel/vdso32/clock_gettime.S
+++ b/arch/s390/kernel/vdso32/clock_gettime.S
@@ -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

diff --git a/arch/s390/kernel/vdso32/getcpu.S b/arch/s390/kernel/vdso32/getcpu.S
index 539d92a2c61b19e15ffa351b4a031d55a11cfff9..25515f3fbcea8283b52b76739541c326b39d2683 100644 (file)
--- a/arch/s390/kernel/vdso32/getcpu.S
+++ b/arch/s390/kernel/vdso32/getcpu.S
@@ -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

diff --git a/arch/s390/kernel/vdso32/gettimeofday.S b/arch/s390/kernel/vdso32/gettimeofday.S
index 435f819c3e65ee1a06faa6a697bd3285937d8c7e..3c0db0fa6ad90304929e7263ea2ca07bbe077eca 100644 (file)
--- a/arch/s390/kernel/vdso32/gettimeofday.S
+++ b/arch/s390/kernel/vdso32/gettimeofday.S
@@ -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

diff --git a/arch/s390/kernel/vdso64/clock_getres.S b/arch/s390/kernel/vdso64/clock_getres.S
index 5b0d9c380de255f2e51816ed94fc8c5b1df35414..081435398e0a1f9690b2305e765576cb5c7da054 100644 (file)
--- a/arch/s390/kernel/vdso64/clock_getres.S
+++ b/arch/s390/kernel/vdso64/clock_getres.S
@@ -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

diff --git a/arch/s390/kernel/vdso64/clock_gettime.S b/arch/s390/kernel/vdso64/clock_gettime.S
index deccd793b2796eefc005853b17f07eeecb91d3ba..fac3ab5ec83a9c3a73f9201b5e094309dda3a1a9 100644 (file)
--- a/arch/s390/kernel/vdso64/clock_gettime.S
+++ b/arch/s390/kernel/vdso64/clock_gettime.S
@@ -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

diff --git a/arch/s390/kernel/vdso64/getcpu.S b/arch/s390/kernel/vdso64/getcpu.S
index 022acdecd5b9dd0eaa9d1751c4ef14e3a3f540db..2446e9dac8ab9cd77db7295f001cd63af97aff6d 100644 (file)
--- a/arch/s390/kernel/vdso64/getcpu.S
+++ b/arch/s390/kernel/vdso64/getcpu.S
@@ -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

diff --git a/arch/s390/kernel/vdso64/gettimeofday.S b/arch/s390/kernel/vdso64/gettimeofday.S
index 964afb1de06d301e9fd976143d9c4db1ca1aba77..6e1f0b421695ac5c4b4bee16adee3690bf89b705 100644 (file)
--- a/arch/s390/kernel/vdso64/gettimeofday.S
+++ b/arch/s390/kernel/vdso64/gettimeofday.S
@@ -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