linux-kernel - Re: [PATCH v4 00/57] x86/dumpstack: rewrite x86 stack dump code

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Date:	Thu, 18 Aug 2016 09:31:36 -0500
From:	Josh Poimboeuf <jpoimboe@...hat.com>
To:	Ingo Molnar <mingo@...nel.org>
Cc:	Frederic Weisbecker <fweisbec@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H . Peter Anvin" <hpa@...or.com>, x86@...nel.org,
	linux-kernel@...r.kernel.org,
	Andy Lutomirski <luto@...capital.net>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Brian Gerst <brgerst@...il.com>,
	Kees Cook <keescook@...omium.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Byungchul Park <byungchul.park@....com>,
	Nilay Vaish <nilayvaish@...il.com>
Subject: Re: [PATCH v4 00/57] x86/dumpstack: rewrite x86 stack dump code

On Thu, Aug 18, 2016 at 03:39:35PM +0200, Ingo Molnar wrote:
> 
> * Frederic Weisbecker <fweisbec@...il.com> wrote:
> 
> > > Josh Poimboeuf (57):
> > 
> > I am personally unable to review a 57 patches series.
> > 
> > Any chance you could split it into self-contained steps? In general doing so 
> > increase the chances for reviews, accelerate merging, improve maintainance...
> 
> Yes, please!
> 
> Series of no more than 4-6 patches, ordered in a logical fasion from lowest risk / 
> simplest towards highest risk / most complex.

You're right, that would be better.  My apologies for spamming.  It
started with "only" 19 patches in v1 and then quickly got out of hand.

I may split it up something like this:

cleanups:
  x86/dumpstack: remove show_trace()
  x86/asm/head: remove unused init_rsp variable extern
  x86/asm/head: rename 'stack_start' -> 'initial_stack'
  x86/dumpstack: add IRQ_USABLE_STACK_SIZE define
  x86/dumpstack: remove extra brackets around "<EOE>"
  x86/head: remove useless zeroed word
  x86/dumpstack: fix x86_32 kernel_stack_pointer() previous stack access
  proc: fix return address printk conversion specifer in /proc/<pid>/stack
  x86: remove 64-byte gap at end of irq stack

function graph fixes:
  ftrace: remove CONFIG_HAVE_FUNCTION_GRAPH_FP_TEST from config
  ftrace: only allocate the ret_stack 'fp' field when needed
  ftrace: add return address pointer to ftrace_ret_stack
  ftrace: add ftrace_graph_ret_addr() stack unwinding helpers
  x86/dumpstack/ftrace: convert dump_trace() callbacks to use ftrace_graph_ret_addr()
  ftrace/x86: implement HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
  x86/dumpstack/ftrace: mark function graph handler function as unreliable
  x86/dumpstack/ftrace: don't print unreliable addresses in print_context_stack_bp()

get_stack_info():
  x86/dumpstack: simplify in_exception_stack()
  x86/dumpstack: add get_stack_info() interface
  x86/dumpstack: add recursion checking for all stacks

unwinder prep:
  perf/x86: check perf_callchain_store() error
  oprofile/x86: add regs->ip to oprofile trace
  x86/dumpstack: remove unnecessary stack pointer arguments
  x86/dumpstack: add get_stack_pointer() and get_frame_pointer()
  x86/dumpstack: make printk_stack_address() more generally useful
  x86/dumpstack: fix irq stack bounds calculation in show_stack_log_lvl()
  x86/dumpstack: allow preemption in show_stack_log_lvl() and dump_trace()

unwinder:
  x86/unwind: add new unwind interface and implementations
  perf/x86: convert perf_callchain_kernel() to use the new unwinder
  x86/stacktrace: convert save_stack_trace_*() to use the new unwinder
  oprofile/x86: convert x86_backtrace() to use the new unwinder
  x86/dumpstack: convert show_trace_log_lvl() to use the new unwinder
  x86/dumpstack: remove dump_trace() and related callbacks

hardened usercopy:
  x86/mm: move arch_within_stack_frames() to usercopy.c
  x86/mm: convert arch_within_stack_frames() to use the new unwinder
  x86/mm: simplify starting frame logic for hardened usercopy
  x86/mm: removed unused arch_within_stack_frames() arguments
  mm: re-enable gcc frame address warning

standardize the end of the stack:
  x86/entry/head/32: use local labels
  x86/asm/head: use a common function for starting CPUs
  x86: move _stext marker to before head code
  x86/head: put real return address on idle task stack
  x86/head: fix the end of the stack for idle tasks
  x86/entry/32: fix the end of the stack for newly forked tasks
  x86/head/32: fix the end of the stack for idle tasks
  x86/smp: fix initial idle stack location on 32-bit
  x86/entry/32: rename 'error_code' to 'common_exception'

pt_regs frames:
  x86/entry/unwind: create stack frames for saved interrupt registers
  x86/unwind: create stack frames for saved syscall registers
  x86/dumpstack: print stack identifier on its own line
  x86/dumpstack: print any pt_regs found on the stack
  x86/dumpstack: fix duplicate RIP address display in __show_regs()
  x86/dumpstack: print orig_ax in __show_regs()

unwinder warnings:
  x86/unwind: warn on kernel stack corruption
  x86/unwind: warn on bad stack return address
  x86/unwind: warn if stack grows up
  x86/dumpstack: warn on stack recursion

-- 
Josh