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author | Frederic Weisbecker <fweisbec@gmail.com> | 2011-01-06 14:22:47 (GMT) |
---|---|---|
committer | Frederic Weisbecker <fweisbec@gmail.com> | 2011-01-07 16:40:56 (GMT) |
commit | 625dbc3b8acbefefefe27e1d7bbc6e53eb4f3f2d (patch) | |
tree | d27741bbc7397b6982ae5f0fd2cb06629c98ea1c /arch/x86 | |
parent | 39a6eebda253aa34d659ca9436e3c32ef60473f1 (diff) | |
download | linux-625dbc3b8acbefefefe27e1d7bbc6e53eb4f3f2d.tar.xz |
x86: Save rbp in pt_regs on irq entry
From the x86_64 low level interrupt handlers, the frame pointer is
saved right after the partial pt_regs frame.
rbp is not supposed to be part of the irq partial saved registers,
but it only requires to extend the pt_regs frame by 8 bytes to
do so, plus a tiny stack offset fixup on irq exit.
This changes a bit the semantics or get_irq_entry() that is supposed
to provide only the value of caller saved registers and the cpu
saved frame. However it's a win for unwinders that can walk through
stack frames on top of get_irq_regs() snapshots.
A noticeable impact is that it makes perf events cpu-clock and
task-clock events based callchains working on x86_64.
Let's then save rbp into the irq pt_regs.
As a result with:
perf record -e cpu-clock perf bench sched messaging
perf report --stdio
Before:
20.94% perf [kernel.kallsyms] [k] lock_acquire
|
--- lock_acquire
|
|--44.01%-- __write_nocancel
|
|--43.18%-- __read
|
|--6.08%-- fork
| create_worker
|
|--0.88%-- _dl_fixup
|
|--0.65%-- do_lookup_x
|
|--0.53%-- __GI___libc_read
--4.67%-- [...]
After:
19.23% perf [kernel.kallsyms] [k] __lock_acquire
|
--- __lock_acquire
|
|--97.74%-- lock_acquire
| |
| |--21.82%-- _raw_spin_lock
| | |
| | |--37.26%-- unix_stream_recvmsg
| | | sock_aio_read
| | | do_sync_read
| | | vfs_read
| | | sys_read
| | | system_call
| | | __read
| | |
| | |--24.09%-- unix_stream_sendmsg
| | | sock_aio_write
| | | do_sync_write
| | | vfs_write
| | | sys_write
| | | system_call
| | | __write_nocancel
v2: Fix cfi annotations.
Reported-by: Soeren Sandmann Pedersen <sandmann@redhat.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: H. Peter Anvin <hpa@zytor.com
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Jan Beulich <JBeulich@novell.com>
Diffstat (limited to 'arch/x86')
-rw-r--r-- | arch/x86/kernel/entry_64.S | 36 |
1 files changed, 23 insertions, 13 deletions
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S index e3ba417..d3b895f 100644 --- a/arch/x86/kernel/entry_64.S +++ b/arch/x86/kernel/entry_64.S @@ -299,17 +299,21 @@ ENDPROC(native_usergs_sysret64) ENTRY(save_args) XCPT_FRAME cld - movq_cfi rdi, RDI+16-ARGOFFSET - movq_cfi rsi, RSI+16-ARGOFFSET - movq_cfi rdx, RDX+16-ARGOFFSET - movq_cfi rcx, RCX+16-ARGOFFSET - movq_cfi rax, RAX+16-ARGOFFSET - movq_cfi r8, R8+16-ARGOFFSET - movq_cfi r9, R9+16-ARGOFFSET - movq_cfi r10, R10+16-ARGOFFSET - movq_cfi r11, R11+16-ARGOFFSET - - leaq -ARGOFFSET+16(%rsp),%rdi /* arg1 for handler */ + /* + * start from rbp in pt_regs and jump over + * return address. + */ + movq_cfi rdi, RDI+8-RBP + movq_cfi rsi, RSI+8-RBP + movq_cfi rdx, RDX+8-RBP + movq_cfi rcx, RCX+8-RBP + movq_cfi rax, RAX+8-RBP + movq_cfi r8, R8+8-RBP + movq_cfi r9, R9+8-RBP + movq_cfi r10, R10+8-RBP + movq_cfi r11, R11+8-RBP + + leaq -RBP+8(%rsp),%rdi /* arg1 for handler */ movq_cfi rbp, 8 /* push %rbp */ leaq 8(%rsp), %rbp /* mov %rsp, %ebp */ testl $3, CS(%rdi) @@ -782,8 +786,9 @@ END(interrupt) /* 0(%rsp): ~(interrupt number) */ .macro interrupt func - subq $ORIG_RAX-ARGOFFSET+8, %rsp - CFI_ADJUST_CFA_OFFSET ORIG_RAX-ARGOFFSET+8 + /* reserve pt_regs for scratch regs and rbp */ + subq $ORIG_RAX-RBP, %rsp + CFI_ADJUST_CFA_OFFSET ORIG_RAX-RBP call save_args PARTIAL_FRAME 0 call \func @@ -808,9 +813,14 @@ ret_from_intr: TRACE_IRQS_OFF decl PER_CPU_VAR(irq_count) leaveq + CFI_RESTORE rbp CFI_DEF_CFA_REGISTER rsp CFI_ADJUST_CFA_OFFSET -8 + + /* we did not save rbx, restore only from ARGOFFSET */ + addq $8, %rsp + CFI_ADJUST_CFA_OFFSET -8 exit_intr: GET_THREAD_INFO(%rcx) testl $3,CS-ARGOFFSET(%rsp) |