[PATCH v4 0/8] x86: use new text_poke_bp in ftrace
The commit fd4363fff3d9 (x86: Introduce int3 (breakpoint)-based instruction
patching) uses the same technique that has been used in ftrace since 08d636b
("ftrace/x86: Have arch x86_64 use breakpoints instead of stop machine")
This patch set merge the two implementations and remove duplicities from
the ftrace side.
+ First four patches improve the generic int3-based framework to be usable
with ftrace. All the changes are based on ideas already used in ftrace.
They are needed to keep the functionality and efficiency.
+ The 5th patch speedups the original ftrace code but it is useful also
with the generic functions.
+ The last three patches modifies different parts of the current
x86-specific ftrace implementation and use the generic functions there.
Changes in v4:
+ reverted one change in text_poke in the first patch as suggested by
Masami Hiramatsu; it means to still call BUG_ON() when the error is
unclear
Changes in v3:
+ use the new text_poke_part only in text_poke_bp_list because it
works only with read-write code
+ update all text_poke functions to return error instead on calling BUG()
+ handle text_poke* function return values whenever they were used
Changes in v2:
+ check for number of CPUs instead of enabling IRQs when syncing CPUs;
suggested by Steven Rostedt, Paul E. McKenney, and Masami Hiramatsu
+ return error codes in text_poke_part and text_poke_bp; needed by ftrace
+ reverted changes in text_poke_bp; it patches only single address again
+ introduce text_poke_bp_iter for patching multiple addresses:
+ uses iterator and callbacks instead of copying data
+ checks old code before patching
+ returns error code and more info about error; needed by ftrace
+ provides recovery mechanism in case of errors
+ update ftrace.c to use the new text_poke_bp_iter
+ split notrace __probe_kernel_read into separate patch because it
is useful for original ftrace code as well
+ rebased on current kernel tip and updated performance statistics;
it started to be slower on idle machine after the commit commit
c229828ca6bc62d6c654 (rcu: Throttle rcu_try_advance_all_cbs() execution)
I tried to switch between 7 tracers: blk, branch, function_graph, wakeup_rt,
irqsoff, function, and nop. Every tracer has also been enabled and disabled.
With 500 cycles, I got these times before the change:
real18m2.477s 18m8.654s 18m9.196s
user0m0.008s 0m0.008s 0m0.012s
sys 0m17.316s 0m17.104s 0m17.300s
and after
real17m19.055s17m29.200s17m27.456
user0m0.052s 0m0.056s 0m0.052s
sys 0m20.236s 0m20.068s 0m20.264s
The patches are against kernel/git/tip/tip.git on top of the commit
af7949e870d4632b Merge branch 'tools/kvm perf fixes'
Petr Mladek (8):
x86: allow to handle errors in text_poke function family
x86: allow to call text_poke_bp during boot
x86: add generic function to modify more calls using int3 framework
x86: speed up int3-based patching using direct write
x86: do not trace __probe_kernel_read
x86: modify ftrace function using the new int3-based framework
x86: patch all traced function calls using the int3-based framework
x86: enable/disable ftrace graph call using new int3-based framework
arch/x86/include/asm/alternative.h | 43 ++-
arch/x86/kernel/alternative.c | 369 +---
arch/x86/kernel/ftrace.c | 571 -
arch/x86/kernel/jump_label.c | 11 +-
arch/x86/kernel/kgdb.c | 11 +-
arch/x86/kernel/kprobes/core.c | 10 +-
arch/x86/kernel/kprobes/opt.c | 8 +-
arch/x86/kernel/traps.c| 10 -
include/linux/ftrace.h | 6 -
mm/maccess.c | 2 +-
10 files changed, 527 insertions(+), 514 deletions(-)
--
1.8.4
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[PATCH v4 0/8] x86: use new text_poke_bp in ftrace
The commit fd4363fff3d9 (x86: Introduce int3 (breakpoint)-based instruction patching) uses the same technique that has been used in ftrace since 08d636b (ftrace/x86: Have arch x86_64 use breakpoints instead of stop machine) This patch set merge the two implementations and remove duplicities from the ftrace side. + First four patches improve the generic int3-based framework to be usable with ftrace. All the changes are based on ideas already used in ftrace. They are needed to keep the functionality and efficiency. + The 5th patch speedups the original ftrace code but it is useful also with the generic functions. + The last three patches modifies different parts of the current x86-specific ftrace implementation and use the generic functions there. Changes in v4: + reverted one change in text_poke in the first patch as suggested by Masami Hiramatsu; it means to still call BUG_ON() when the error is unclear Changes in v3: + use the new text_poke_part only in text_poke_bp_list because it works only with read-write code + update all text_poke functions to return error instead on calling BUG() + handle text_poke* function return values whenever they were used Changes in v2: + check for number of CPUs instead of enabling IRQs when syncing CPUs; suggested by Steven Rostedt, Paul E. McKenney, and Masami Hiramatsu + return error codes in text_poke_part and text_poke_bp; needed by ftrace + reverted changes in text_poke_bp; it patches only single address again + introduce text_poke_bp_iter for patching multiple addresses: + uses iterator and callbacks instead of copying data + checks old code before patching + returns error code and more info about error; needed by ftrace + provides recovery mechanism in case of errors + update ftrace.c to use the new text_poke_bp_iter + split notrace __probe_kernel_read into separate patch because it is useful for original ftrace code as well + rebased on current kernel tip and updated performance statistics; it started to be slower on idle machine after the commit commit c229828ca6bc62d6c654 (rcu: Throttle rcu_try_advance_all_cbs() execution) I tried to switch between 7 tracers: blk, branch, function_graph, wakeup_rt, irqsoff, function, and nop. Every tracer has also been enabled and disabled. With 500 cycles, I got these times before the change: real18m2.477s 18m8.654s 18m9.196s user0m0.008s 0m0.008s 0m0.012s sys 0m17.316s 0m17.104s 0m17.300s and after real17m19.055s17m29.200s17m27.456 user0m0.052s 0m0.056s 0m0.052s sys 0m20.236s 0m20.068s 0m20.264s The patches are against kernel/git/tip/tip.git on top of the commit af7949e870d4632b Merge branch 'tools/kvm perf fixes' Petr Mladek (8): x86: allow to handle errors in text_poke function family x86: allow to call text_poke_bp during boot x86: add generic function to modify more calls using int3 framework x86: speed up int3-based patching using direct write x86: do not trace __probe_kernel_read x86: modify ftrace function using the new int3-based framework x86: patch all traced function calls using the int3-based framework x86: enable/disable ftrace graph call using new int3-based framework arch/x86/include/asm/alternative.h | 43 ++- arch/x86/kernel/alternative.c | 369 +--- arch/x86/kernel/ftrace.c | 571 - arch/x86/kernel/jump_label.c | 11 +- arch/x86/kernel/kgdb.c | 11 +- arch/x86/kernel/kprobes/core.c | 10 +- arch/x86/kernel/kprobes/opt.c | 8 +- arch/x86/kernel/traps.c| 10 - include/linux/ftrace.h | 6 - mm/maccess.c | 2 +- 10 files changed, 527 insertions(+), 514 deletions(-) -- 1.8.4 -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
