breakpoints/2430: assembler file with multiple sections which is not adjacent can't step

[jianghongjiang at gmail dot com]

>Number:         2430
>Category:       breakpoints
>Synopsis:       assembler file with multiple sections which is not adjacent can't step
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    unassigned
>State:          open
>Class:          change-request
>Submitter-Id:   net
>Arrival-Date:   Fri Mar 14 09:08:01 UTC 2008
>Closed-Date:
>Last-Modified:
>Originator:     jianghongjiang@gmail.com
>Release:        gdb6.6
>Organization:
>Environment:

>Description:
Recently I using the arm-gdb to debug my arm code, and find some "bugs" in arm-gdb. One of my assembler source has 3 sections------".init",".text",".fini", these 3 sections are not adjacent after link, the ".init" section comes first, then the".text" section ,and finally the ".fini". I set a breakpoint in the line of the ".init" section, and used "r" command in arm-gdb then it stop in correct position, then I typed "step" command attempting that it will stops in the next line, but gdb warned the following messages:

"Cannot find bounds of current function,Single stepping until exit from function __rest,which has no line number information."

I tracked the execution of the gdb for a while, and finally find the problem. In dbxread.c, there is a function "read_dbx_symtab", this function initialize the 
the "psymtabs" member of global var "object_files"(and also other functions, but I don't care), the psymtabs chain is created from the debug information in the final exectuable
file, mainly the stabs debug inforamtion whose type is "N_SO". The psymtabs's textlow member is determided by this "N_SO" stabs's value, which is this file's inital ".text" section address in the final executable file. For example, the final address of this 3 sections shows in follow:

.init:  0x0 	- 0x200
.text:  0x500	- 0x600
.fini:  0x900   - 0xC00

then the textlow and texthigh member of the psymtabs node in psymtabs chain of this assemble file is 0x500 and 0x600! I made a change in "read_dbx_symtab", and the textlow and texthigh is 0x0 and 0xC00, but when I set a breakpoint in the ".fini" section soure line and use "step" after break, there comes an another problem, the gdb executes this assemble's code, but it displays other's assembler file's
contents.This assembler's code range is 0x700-0x800. 
    
    For the situation of single assembler file containing several sections which are not adjacent, I suggest that during psymtabs creating, there should be multiple psymtabs
node for individual sections, with which sharing a file(their "filename" member is same).
	
   The gdb version is :
	
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