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/asm-offsets.c | 2 ++
arch/s390/kernel/entry.S | 12 ++++++++++++
arch/s390/kernel/entry64.S | 12 ++++++++++++
arch/s390/kernel/hw_breakpoint.c | 28 +++++++++++++++++++++-------
5 files changed, 55 insertions(+), 9 deletions(-)
diff --git a/arch/s390/include/asm/lowcore.h b/arch/s390/include/asm/lowcore.h
index 05527c0..a9d3c5f 100644
--- a/arch/s390/include/asm/lowcore.h
+++ b/arch/s390/include/asm/lowcore.h
@@ -135,7 +135,10 @@ struct _lowcore {
__u64 clock_comparator; /* 0x02d0 */
__u32 machine_flags; /* 0x02d8 */
__u32 ftrace_func; /* 0x02dc */
- __u8 pad_0x02e0[0x0300-0x02e0]; /* 0x02e0 */
+
+ /* Kernel PER tracing mask */
+ __u32 kernel_per_tracing_mask; /* 0x02e0 */
+ __u8 pad_0x02e4[0x0300-0x02e4]; /* 0x02e4 */
/* Interrupt response block */
__u8 irb[64]; /* 0x0300 */
@@ -265,7 +268,10 @@ 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/asm-offsets.c b/arch/s390/kernel/asm-offsets.c
index a094089..abb33ec 100644
--- a/arch/s390/kernel/asm-offsets.c
+++ b/arch/s390/kernel/asm-offsets.c
@@ -130,6 +130,8 @@ int main(void)
DEFINE(__LC_INT_CLOCK, offsetof(struct _lowcore, int_clock));
DEFINE(__LC_MACHINE_FLAGS, offsetof(struct _lowcore, machine_flags));
DEFINE(__LC_FTRACE_FUNC, offsetof(struct _lowcore, ftrace_func));
+ DEFINE(__LC_KERNEL_PER_TRACING_MASK,
+ offsetof(struct _lowcore, kernel_per_tracing_mask));
DEFINE(__LC_IRB, offsetof(struct _lowcore, irb));
DEFINE(__LC_CPU_TIMER_SAVE_AREA, offsetof(struct _lowcore, cpu_timer_save_area));
DEFINE(__LC_CLOCK_COMP_SAVE_AREA, offsetof(struct _lowcore, clock_comp_save_area));
diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S
index 6af7045..2f93424 100644
--- a/arch/s390/kernel/entry.S
+++ b/arch/s390/kernel/entry.S
@@ -266,6 +266,10 @@ 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)
@@ -604,6 +608,10 @@ 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
@@ -750,6 +758,10 @@ 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 52106d5..adfb985 100644
--- a/arch/s390/kernel/entry64.S
+++ b/arch/s390/kernel/entry64.S
@@ -260,6 +260,10 @@ 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
@@ -579,6 +583,10 @@ 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
@@ -744,6 +752,10 @@ 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 1cce08e..19c5bb5 100644
--- a/arch/s390/kernel/hw_breakpoint.c
+++ b/arch/s390/kernel/hw_breakpoint.c
@@ -82,6 +82,19 @@ 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 (!bp->attr.exclude_kernel
+ && 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];
@@ -93,13 +106,7 @@ int arch_install_hw_breakpoint(struct perf_event *bp)
*/
if (!bp->attr.exclude_kernel) {
/* Enable 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.
@@ -148,7 +155,14 @@ void arch_uninstall_hw_breakpoint(struct perf_event *bp)
if (!bp->attr.exclude_kernel) {
/* clear 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);
+ }
}
if (tsk) {
/* clear breakpoint bound to a task context */
--
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