Re: [PATCH] Testsuite: Ensure stack protection is off for GCC

[Alan Hayward <Alan dot Hayward at arm dot com>]

Forgot to mention: this fixes ~60 tests when running make check on Ubuntu.


> On 7 Jan 2019, at 16:37, Alan Hayward <Alan.Hayward@arm.com> wrote:
> 
> Using -fstack-protector-strong will cause GDB to break on the wrong line
> when placing a breakpoint on a function.  This is caused by due to
> inadequate dwarf line numbering, and is being tracked by the GCC bug
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88432
> 
> GCC (and Clang) provided by Debian/Ubuntu default to Stack Protector
> being enabled.
> 
> So, ensure that when running the GDB testsuite, stack protector is always
> turned off for GCC (option has existed since GCC 4.1.0).
> 
> Also, ensure that this does not cause infinite recursion due to
> test_compiler_info having to compile a file itself.
> 
> Restore change in ovldbreak.exp which worked around the issue.
> 
> [Side note - this fix would be improved by checking for Ubuntu/Debian,
> but I don't see any existing checks for that in the testsuite]
> 
> 2019-01-07  Alan Hayward  <alan.hayward@arm.com>
> 
> 	* gdb.cp/ovldbreak.exp: Only allow a single break line.
> 	* lib/gdb.exp (get_compiler_info): Use getting_compiler_info option.
> 	(gdb_compile): Remove stack protector for GCC and prevent recursion.
> ---
> gdb/testsuite/gdb.cp/ovldbreak.exp |  2 +-
> gdb/testsuite/lib/gdb.exp          | 17 +++++++++++++++--
> 2 files changed, 16 insertions(+), 3 deletions(-)
> 
> diff --git a/gdb/testsuite/gdb.cp/ovldbreak.exp b/gdb/testsuite/gdb.cp/ovldbreak.exp
> index 494f2a12e9..3ffd04209a 100644
> --- a/gdb/testsuite/gdb.cp/ovldbreak.exp
> +++ b/gdb/testsuite/gdb.cp/ovldbreak.exp
> @@ -209,7 +209,7 @@ for {set idx 0} {$idx < [llength $overloads]} {incr idx} {
> 
> # Verify the breakpoints.
> set bptable "Num\[\t \]+Type\[\t \]+Disp Enb Address\[\t \]+What.*\[\r\n]+"
> -append bptable "\[0-9\]+\[\t \]+breakpoint\[\t \]+keep\[\t \]y\[\t \]+$hex\[\t \]+in main(\\((|void)\\))? at.*$srcfile:4\[89\]\[\r\n\]+"
> +append bptable "\[0-9\]+\[\t \]+breakpoint\[\t \]+keep\[\t \]y\[\t \]+$hex\[\t \]+in main(\\((|void)\\))? at.*$srcfile:49\[\r\n\]+"
> append bptable "\[\t \]+breakpoint already hit 1 time\[\r\n\]+."
> foreach ovld $overloads {
>     append bptable [format "\[0-9\]+\[\t \]+breakpoint\[\t \]+keep y\[\t \]+$hex\[\t \]+in foo::overload1arg\\(%s\\) at.*$srcfile:%d\[\r\n\]+" $ovld \
> diff --git a/gdb/testsuite/lib/gdb.exp b/gdb/testsuite/lib/gdb.exp
> index ed9f89d5a7..7443638a72 100644
> --- a/gdb/testsuite/lib/gdb.exp
> +++ b/gdb/testsuite/lib/gdb.exp
> @@ -3276,12 +3276,12 @@ proc get_compiler_info {{arg ""}} {
> 	# We have to use -E and -o together, despite the comments
> 	# above, because of how DejaGnu handles remote host testing.
> 	set ppout "$outdir/compiler.i"
> -	gdb_compile "${ifile}" "$ppout" preprocess [list "$arg" quiet]
> +	gdb_compile "${ifile}" "$ppout" preprocess [list "$arg" quiet getting_compiler_info]
> 	set file [open $ppout r]
> 	set cppout [read $file]
> 	close $file
>     } else {
> -	set cppout [ gdb_compile "${ifile}" "" preprocess [list "$arg" quiet] ]
> +	set cppout [ gdb_compile "${ifile}" "" preprocess [list "$arg" quiet getting_compiler_info] ]
>     }
>     eval log_file $saved_log
> 
> @@ -3519,6 +3519,7 @@ proc gdb_compile {source dest type options} {
>     }
>     set shlib_found 0
>     set shlib_load 0
> +    set getting_compiler_info 0
>     foreach opt $options {
>         if {[regexp {^shlib=(.*)} $opt dummy_var shlib_name]
> 	    && $type == "executable"} {
> @@ -3549,11 +3550,23 @@ proc gdb_compile {source dest type options} {
>             }
> 	} elseif { $opt == "shlib_load" && $type == "executable" } {
> 	    set shlib_load 1
> +	} elseif { $opt == "getting_compiler_info" } {
> +	    # If this is set, calling test_compiler_info will cause recursion.
> +	    set getting_compiler_info 1
>         } else {
>             lappend new_options $opt
>         }
>     }
> 
> +    # Ensure stack protector is disabled for GCC, as this will causes problems
> +    # with DWARF line numbering.
> +    # See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88432
> +    # This option defaults to on for Debian/Ubuntu.
> +    if { $getting_compiler_info == 0 && [test_compiler_info "gcc-*"] } {
> +        # Put it at the front to not override any user-provided value
> +        lappend new_options "early_flags=-fno-stack-protector"
> +    }
> +
>     # Because we link with libraries using their basename, we may need
>     # (depending on the platform) to set a special rpath value, to allow
>     # the executable to find the libraries it depends on.
> -- 
> 2.17.2 (Apple Git-113)
>