linux-kernel - Re: [PATCH] kallsyms, tracing: output more proper symbol name

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Date:	Wed, 11 Mar 2009 10:46:21 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Lai Jiangshan <laijs@...fujitsu.com>
Cc:	Sam Ravnborg <sam@...nborg.org>, Andrew Morton <akpm@...l.org>,
	Steven Rostedt <srostedt@...hat.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] kallsyms, tracing: output more proper symbol name


* Lai Jiangshan <laijs@...fujitsu.com> wrote:

> +#define VMLINUX_SYMBOL(_sym_) #_sym_
> +
> +static const char *hide_symbols[] = {
> +	/* misc symbols */
> +	"_text",
> +	"_stext",
> +	"_etext",
> +	"_sinittext",
> +	"_einittext",
> +
> +	/* symbols from include/asm-generic/vmlinux.lds.h */
> +	VMLINUX_SYMBOL(__start_mcount_loc),
> +	VMLINUX_SYMBOL(__stop_mcount_loc),
> +	VMLINUX_SYMBOL(__start_annotated_branch_profile),
> +	VMLINUX_SYMBOL(__stop_annotated_branch_profile),
> +	VMLINUX_SYMBOL(__start_branch_profile),
> +	VMLINUX_SYMBOL(__stop_branch_profile),
> +	VMLINUX_SYMBOL(__start___markers),
> +	VMLINUX_SYMBOL(__stop___markers),
> +	VMLINUX_SYMBOL(__start___tracepoints),
> +	VMLINUX_SYMBOL(__stop___tracepoints),
> +	VMLINUX_SYMBOL(__start_rodata),
> +	VMLINUX_SYMBOL(__start_pci_fixups_early),
> +	VMLINUX_SYMBOL(__end_pci_fixups_early),
> +	VMLINUX_SYMBOL(__start_pci_fixups_header),
> +	VMLINUX_SYMBOL(__end_pci_fixups_header),
> +	VMLINUX_SYMBOL(__start_pci_fixups_final),
> +	VMLINUX_SYMBOL(__end_pci_fixups_final),
> +	VMLINUX_SYMBOL(__start_pci_fixups_enable),
> +	VMLINUX_SYMBOL(__end_pci_fixups_enable),
> +	VMLINUX_SYMBOL(__start_pci_fixups_resume),
> +	VMLINUX_SYMBOL(__end_pci_fixups_resume),
> +	VMLINUX_SYMBOL(__start_pci_fixups_resume_early),
> +	VMLINUX_SYMBOL(__end_pci_fixups_resume_early),
> +	VMLINUX_SYMBOL(__start_pci_fixups_suspend),
> +	VMLINUX_SYMBOL(__end_pci_fixups_suspend),
> +	VMLINUX_SYMBOL(__start_builtin_fw),
> +	VMLINUX_SYMBOL(__end_builtin_fw),
> +	VMLINUX_SYMBOL(__start_rio_route_ops),
> +	VMLINUX_SYMBOL(__end_rio_route_ops),
> +	VMLINUX_SYMBOL(__start___ksymtab),
> +	VMLINUX_SYMBOL(__stop___ksymtab),
> +	VMLINUX_SYMBOL(__start___ksymtab_gpl),
> +	VMLINUX_SYMBOL(__stop___ksymtab_gpl),
> +	VMLINUX_SYMBOL(__start___ksymtab_unused),
> +	VMLINUX_SYMBOL(__stop___ksymtab_unused),
> +	VMLINUX_SYMBOL(__start___ksymtab_unused_gpl),
> +	VMLINUX_SYMBOL(__stop___ksymtab_unused_gpl),
> +	VMLINUX_SYMBOL(__start___ksymtab_gpl_future),
> +	VMLINUX_SYMBOL(__stop___ksymtab_gpl_future),
> +	VMLINUX_SYMBOL(__start___kcrctab),
> +	VMLINUX_SYMBOL(__stop___kcrctab),
> +	VMLINUX_SYMBOL(__start___kcrctab_gpl),
> +	VMLINUX_SYMBOL(__stop___kcrctab_gpl),
> +	VMLINUX_SYMBOL(__start___kcrctab_unused),
> +	VMLINUX_SYMBOL(__stop___kcrctab_unused),
> +	VMLINUX_SYMBOL(__start___kcrctab_unused_gpl),
> +	VMLINUX_SYMBOL(__stop___kcrctab_unused_gpl),
> +	VMLINUX_SYMBOL(__start___kcrctab_gpl_future),
> +	VMLINUX_SYMBOL(__stop___kcrctab_gpl_future),
> +	VMLINUX_SYMBOL(__start___param),
> +	VMLINUX_SYMBOL(__stop___param),
> +	VMLINUX_SYMBOL(__end_rodata),
> +	VMLINUX_SYMBOL(__security_initcall_start),
> +	VMLINUX_SYMBOL(__security_initcall_end),
> +	VMLINUX_SYMBOL(__sched_text_start),
> +	VMLINUX_SYMBOL(__sched_text_end),
> +	VMLINUX_SYMBOL(__lock_text_start),
> +	VMLINUX_SYMBOL(__lock_text_end),
> +	VMLINUX_SYMBOL(__kprobes_text_start),
> +	VMLINUX_SYMBOL(__kprobes_text_end),
> +	VMLINUX_SYMBOL(__irqentry_text_start),
> +	VMLINUX_SYMBOL(__irqentry_text_end),
> +	VMLINUX_SYMBOL(__start___verbose_strings),
> +	VMLINUX_SYMBOL(__stop___verbose_strings),
> +	VMLINUX_SYMBOL(__start___verbose),
> +	VMLINUX_SYMBOL(__stop___verbose),
> +	VMLINUX_SYMBOL(__start___bug_table),
> +	VMLINUX_SYMBOL(__stop___bug_table),
> +	VMLINUX_SYMBOL(__tracedata_start),
> +	VMLINUX_SYMBOL(__tracedata_end),
> +	VMLINUX_SYMBOL(__start_notes),
> +	VMLINUX_SYMBOL(__stop_notes),
> +	VMLINUX_SYMBOL(__early_initcall_end),
> +	VMLINUX_SYMBOL(__per_cpu_start),
> +	VMLINUX_SYMBOL(__per_cpu_end)
> +};

I like how you try to solve this at symbol table generation 
time.

Instead of this hardcoded table, couldnt we use some more 
flexible and more future-proof method? Such as ordering 
same-address symbols by underscores:

  [same address]

  non-underscore symbols first        XYZ
  single-undescroe symbols second     _XYZ
  double-underscore symbols third     __XYZ

that way the scheme would be more or less self-maintaining as an 
underscore already carries a "this is a special, internal 
symbol" notion.

	Ingo
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