Enable kernel PER tracing in the kernel entry point.
A new flag kernel_per_tracing has been added to lowcore for each CPU,
which is checked at every kernel entry point and set the PER bit in
current PSW.
Signed-off-by: Mahesh Salgaonkar <mahesh@xxxxxxxxxxxxxxxxxx>
---
arch/s390/include/asm/lowcore.h | 10 +++++++++-
arch/s390/kernel/entry.S | 12 ++++++++++++
arch/s390/kernel/entry64.S | 12 ++++++++++++
arch/s390/kernel/hw_breakpoint.c | 27 ++++++++++++++++++++-------
4 files changed, 53 insertions(+), 8 deletions(-)
diff --git a/arch/s390/include/asm/lowcore.h b/arch/s390/include/asm/lowcore.h
index f2ef4b6..2e3bdb7 100644
--- a/arch/s390/include/asm/lowcore.h
+++ b/arch/s390/include/asm/lowcore.h
@@ -69,6 +69,7 @@
#define __LC_INT_CLOCK 0x02c8
#define __LC_MACHINE_FLAGS 0x02d8
#define __LC_FTRACE_FUNC 0x02dc
+#define __LC_KERNEL_PER_TRACING_MASK 0x02e0
#define __LC_IRB 0x0300
#define __LC_PFAULT_INTPARM 0x0080
#define __LC_CPU_TIMER_SAVE_AREA 0x00d8
@@ -116,6 +117,7 @@
#define __LC_VDSO_PER_CPU 0x0350
#define __LC_MACHINE_FLAGS 0x0358
#define __LC_FTRACE_FUNC 0x0360
+#define __LC_KERNEL_PER_TRACING_MASK 0x0368
#define __LC_IRB 0x0380
#define __LC_PASTE 0x03c0
#define __LC_PFAULT_INTPARM 0x11b8
@@ -293,6 +295,9 @@ struct _lowcore
__u64 clock_comparator; /* 0x02d0 */
__u32 machine_flags; /* 0x02d8 */
__u32 ftrace_func; /* 0x02dc */
+
+ /* Kernel PER tracing mask */
+ __u32 kernel_per_tracing_mask; /* 0x02e0 */
__u8 pad_0x02f0[0x0300-0x02f0]; /* 0x02f0 */
/* Interrupt response block */
@@ -399,7 +404,10 @@ struct _lowcore
__u64 vdso_per_cpu_data; /* 0x0350 */
__u64 machine_flags; /* 0x0358 */
__u64 ftrace_func; /* 0x0360 */
- __u8 pad_0x0368[0x0380-0x0368]; /* 0x0368 */
+
+ /* Kernel PER tracing mask */
+ __u64 kernel_per_tracing_mask; /* 0x0368 */
+ __u8 pad_0x0370[0x0380-0x0370]; /* 0x0370 */
/* Interrupt response block. */
__u8 irb[64]; /* 0x0380 */
diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S
index e8ef21c..d4a9c2f 100644
--- a/arch/s390/kernel/entry.S
+++ b/arch/s390/kernel/entry.S
@@ -267,6 +267,10 @@ sysc_do_restart:
sth %r7,SP_SVCNR(%r15)
sll %r7,2 # svc number *4
l %r8,BASED(.Lsysc_table)
+ tm __LC_KERNEL_PER_TRACING_MASK,0x40 # kernel per tracing is on?
+ jz sysc_noper
+ stosm __SF_EMPTY(%r15),0x40 # enable per event recording
+sysc_noper:
tm __TI_flags+2(%r9),_TIF_SYSCALL
l %r8,0(%r7,%r8) # get system call addr.
bnz BASED(sysc_tracesys)
@@ -605,6 +609,10 @@ io_int_handler:
io_no_vtime:
l %r9,__LC_THREAD_INFO # load pointer to thread_info struct
TRACE_IRQS_OFF
+ tm __LC_KERNEL_PER_TRACING_MASK,0x40 # kernel per tracing is on?
+ jz io_noper
+ stosm __SF_EMPTY(%r15),0x40 # enable per event recording
+io_noper:
l %r1,BASED(.Ldo_IRQ) # load address of do_IRQ
la %r2,SP_PTREGS(%r15) # address of register-save area
basr %r14,%r1 # branch to standard irq handler
@@ -751,6 +759,10 @@ ext_int_handler:
ext_no_vtime:
l %r9,__LC_THREAD_INFO # load pointer to thread_info struct
TRACE_IRQS_OFF
+ tm __LC_KERNEL_PER_TRACING_MASK,0x40 # kernel per tracing is on?
+ jz ext_noper
+ stosm __SF_EMPTY(%r15),0x40 # enable per event recording
+ext_noper:
la %r2,SP_PTREGS(%r15) # address of register-save area
lh %r3,__LC_EXT_INT_CODE # get interruption code
l %r1,BASED(.Ldo_extint)
diff --git a/arch/s390/kernel/entry64.S b/arch/s390/kernel/entry64.S
index f33658f..aa63e4d 100644
--- a/arch/s390/kernel/entry64.S
+++ b/arch/s390/kernel/entry64.S
@@ -262,6 +262,10 @@ sysc_do_restart:
larl %r10,sys_call_table_emu # use 31 bit emulation system calls
sysc_noemu:
#endif
+ tm __LC_KERNEL_PER_TRACING_MASK,0x40 # kernel per tracing is on?
+ jz sysc_noper
+ stosm __SF_EMPTY(%r15),0x40 # enable per event recording
+sysc_noper:
tm __TI_flags+6(%r9),_TIF_SYSCALL
lgf %r8,0(%r7,%r10) # load address of system call routine
jnz sysc_tracesys
@@ -581,6 +585,10 @@ io_no_vtime:
lg %r9,__LC_THREAD_INFO # load pointer to thread_info struct
TRACE_IRQS_OFF
la %r2,SP_PTREGS(%r15) # address of register-save area
+ tm __LC_KERNEL_PER_TRACING_MASK,0x40 # kernel per tracing is on?
+ jz io_noper
+ stosm __SF_EMPTY(%r15),0x40 # enable per event recording
+io_noper:
brasl %r14,do_IRQ # call standard irq handler
io_return:
tm __TI_flags+7(%r9),_TIF_WORK_INT
@@ -746,6 +754,10 @@ ext_no_vtime:
TRACE_IRQS_OFF
la %r2,SP_PTREGS(%r15) # address of register-save area
llgh %r3,__LC_EXT_INT_CODE # get interruption code
+ tm __LC_KERNEL_PER_TRACING_MASK,0x40 # kernel per tracing is on?
+ jz ext_noper
+ stosm __SF_EMPTY(%r15),0x40 # enable per event recording
+ext_noper:
brasl %r14,do_extint
j io_return
diff --git a/arch/s390/kernel/hw_breakpoint.c b/arch/s390/kernel/hw_breakpoint.c
index a537a48..414036d 100644
--- a/arch/s390/kernel/hw_breakpoint.c
+++ b/arch/s390/kernel/hw_breakpoint.c
@@ -82,6 +82,18 @@ int arch_install_hw_breakpoint(struct perf_event *bp)
per_regs[0].starting_addr = info->address;
per_regs[0].ending_addr = info->address + info->len - 1;
+ if (!tsk && per_regs[0].em_storage_alteration) {
+ /* For kernel wide breakpoints the Storage-Alteration-Space
+ * Control bit as well as the Storage-Alternation-Event bit
+ * in the ASCE needs to be set. Otherwise we might end up
+ * tracing copy_to_user events as well.
+ */
+ per_regs[0].storage_alt_space_ctl = 1;
+ __ctl_set_bit(1, 7);
+ __ctl_set_bit(7, 7);
+ __ctl_set_bit(13, 7);
+ }
+
/* Load the control register 9, 10 and 11 with per info */
__ctl_load(per_regs, 9, 11);
__get_cpu_var(cpu_per_regs[0]) = per_regs[0];
@@ -89,13 +101,7 @@ int arch_install_hw_breakpoint(struct perf_event *bp)
if (((per_cr_words *)per_regs)->cr[0] & PER_EM_MASK) {
if (!tsk) {
/* wide breakpoint in the kernel */
- /* FIXME:
- * It's not good idea to use existing flag in lowcore
- * for turning on/off PER tracing in kernel. instead
- * define a new flag and handle PER tracing checks in
- * entry*.S
- */
-
+ S390_lowcore.kernel_per_tracing_mask |= PSW_MASK_PER;
/* set PER bit int psw_kernel_bits to avoid loosing it
* accidently if someone modifies PSW bit directly.
@@ -140,7 +146,14 @@ void arch_uninstall_hw_breakpoint(struct perf_event *bp)
if (!tsk) {
/* wide breakpoint in the kernel */
+ S390_lowcore.kernel_per_tracing_mask &= ~PSW_MASK_PER;
psw_kernel_bits &= ~PSW_MASK_PER;
+ per_regs[0] = __get_cpu_var(cpu_per_regs[0]);
+ if (per_regs[0].em_storage_alteration) {
+ __ctl_clear_bit(1, 7);
+ __ctl_clear_bit(7, 7);
+ __ctl_clear_bit(13, 7);
+ }
} else {
/* user-space hardware breakpoint */
struct pt_regs *regs = task_pt_regs(tsk);
--
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