Re: [PATCH v3 1/4] xen: introduce CONFIG_GENERIC_BUG_FRAME

[Jan Beulich <jbeulich@suse.com>]

On 24.02.2023 12:31, Oleksii Kurochko wrote:
> --- /dev/null
> +++ b/xen/common/bug.c
> @@ -0,0 +1,109 @@
> +#include <xen/bug.h>
> +#include <xen/debugger.h>
> +#include <xen/errno.h>
> +#include <xen/kernel.h>
> +#include <xen/livepatch.h>
> +#include <xen/string.h>
> +#include <xen/types.h>
> +#include <xen/virtual_region.h>
> +
> +#include <asm/processor.h>
> +
> +/* Set default value for TRAP_invalid_op as it is defined only for X86 now */
> +#ifndef TRAP_invalid_op
> +#define TRAP_invalid_op 0
> +#endif
> +
> +int do_bug_frame(const struct cpu_user_regs *regs, unsigned long pc)
> +{
> +    const struct bug_frame *bug = NULL;
> +    const struct virtual_region *region;
> +    const char *prefix = "", *filename, *predicate;
> +    unsigned long fixup;
> +    unsigned int id = BUGFRAME_NR, lineno;
> +
> +    region = find_text_region(pc);
> +    if ( region )
> +    {
> +        for ( id = 0; id < BUGFRAME_NR; id++ )
> +        {
> +            const struct bug_frame *b;
> +            unsigned int i;
> +
> +            for ( i = 0, b = region->frame[id].bugs;
> +                  i < region->frame[id].n_bugs; b++, i++ )
> +            {
> +                if ( bug_loc(b) == pc )
> +                {
> +                    bug = b;
> +                    goto found;
> +                }
> +            }
> +        }
> +    }
> +
> + found:
> +    if ( !bug )
> +        return -EINVAL;
> +
> +    if ( id == BUGFRAME_run_fn )
> +    {
> +#ifdef BUG_FN_REG
> +        void (*fn)(const struct cpu_user_regs *) = (void *)regs->BUG_FN_REG;
> +#else
> +        void (*fn)(const struct cpu_user_regs *) = bug_ptr(bug);
> +#endif
> +
> +        fn(regs);
> +
> +        return id;
> +    }
> +
> +    /* WARN, BUG or ASSERT: decode the filename pointer and line number. */
> +    filename = bug_ptr(bug);
> +    if ( !is_kernel(filename) && !is_patch(filename) )
> +        return -EINVAL;
> +    fixup = strlen(filename);
> +    if ( fixup > 50 )
> +    {
> +        filename += fixup - 47;
> +        prefix = "...";
> +    }
> +    lineno = bug_line(bug);
> +
> +    switch ( id )
> +    {
> +    case BUGFRAME_warn:
> +        printk("Xen WARN at %s%s:%d\n", prefix, filename, lineno);
> +        show_execution_state(regs);
> +
> +        return id;
> +
> +    case BUGFRAME_bug:
> +        printk("Xen BUG at %s%s:%d\n", prefix, filename, lineno);
> +
> +        if ( debugger_trap_fatal(TRAP_invalid_op, regs) )

TRAP_invalid_op is, as said, about to disappear on x86 as well. I think
this construct wants abstracting by another asm/bug.h provided macro
(taking just regs).

Jan