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Re: [RFA 7/8] New port: TI C6x: test case fixes
- From: Mark Kettenis <mark dot kettenis at xs4all dot nl>
- To: yao at codesourcery dot com
- Cc: gdb-patches at sourceware dot org
- Date: Tue, 9 Aug 2011 17:15:50 +0200 (CEST)
- Subject: Re: [RFA 7/8] New port: TI C6x: test case fixes
- References: <4E263904.8030204@codesourcery.com> <4E2D1AC1.9070102@codesourcery.com> <201108091522.12881.pedro@codesourcery.com> <4E414C49.9020507@codesourcery.com>
> Date: Tue, 09 Aug 2011 23:03:37 +0800
> From: Yao Qi <yao@codesourcery.com>
I really think your approach is rather fragile...
> diff --git a/gdb/testsuite/gdb.base/savedregs.c b/gdb/testsuite/gdb.base/savedregs.c
> index 9f302a0..582afc4 100644
> --- a/gdb/testsuite/gdb.base/savedregs.c
> +++ b/gdb/testsuite/gdb.base/savedregs.c
> @@ -22,6 +22,12 @@
> #include <signal.h>
> #include <sys/time.h>
>
> +#ifdef __UCLIBC__
> +#if !(defined(__UCLIBC_HAS_MMU__) || defined(__ARCH_HAS_MMU__))
> +#define HAS_NOMMU
> +#endif
> +#endif
> +
> static volatile int done;
>
> extern int
> @@ -45,11 +51,27 @@ catcher (int sig)
> static void
> thrower (void)
> {
> +#if defined(HAS_NOMMU)
> +#if defined(__arm__)
> + asm(".word 0xf8f00000");
> +#elif defined(__TMS320C6X__)
> + /* 0x56454314 is also an invalid insn but it causes SIGTRAP in kernel. */
> + asm(".word 0x56454313");
> +#else
> +#error Please write an invalid instruction here for your target
> +#endif
> +#else /* defined(HAS_NOMMU) */
> *(char *)0 = 0;
> +#endif /* defined(HAS_NOMMU) */
> }
>
> main ()
> {
> +#if defined(HAS_NOMMU)
> + signal (SIGILL, catcher);
> +#else
> signal (SIGSEGV, catcher);
> +#endif
> +
> thrower ();
> }
Why depend on this NOMMU-magic? Just install the signal handler for
bth SIGSEGV and SIGILL, try a store to (or perhaps a read from)
address 0, and then fall through to executing an illegal instruction.