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Revision f2d7b53c0153f2daa8bc8f1ff29b5a1e03a36458 authored by Alexander Potapenko on 02 November 2022, 10:15:00 UTC, committed by Alexander Potapenko on 02 November 2022, 10:55:06 UTC 
x86/traps: avoid KMSAN bugs originating from handle_bug()
 
There is a case in exc_invalid_op handler that is executed outside the
irqentry_enter()/irqentry_exit() region when an UD2 instruction is used
to encode a call to __warn().

In that case the `struct pt_regs` passed to the interrupt handler is
never unpoisoned by KMSAN (this is normally done in irqentry_enter()),
which leads to false positives inside handle_bug().

Use kmsan_unpoison_entry_regs() to explicitly unpoison those registers
before using them.

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: x86@kernel.org
Signed-off-by: Alexander Potapenko <glider@google.com>
1 parent 4dbc4d5
Raw File
show_mem.c 
// SPDX-License-Identifier: GPL-2.0-only
/*
 * Generic show_mem() implementation
 *
 * Copyright (C) 2008 Johannes Weiner <hannes@saeurebad.de>
 */

#include <linux/mm.h>
#include <linux/cma.h>

void __show_mem(unsigned int filter, nodemask_t *nodemask, int max_zone_idx)
{
	pg_data_t *pgdat;
	unsigned long total = 0, reserved = 0, highmem = 0;

	printk("Mem-Info:\n");
	__show_free_areas(filter, nodemask, max_zone_idx);

	for_each_online_pgdat(pgdat) {
		int zoneid;

		for (zoneid = 0; zoneid < MAX_NR_ZONES; zoneid++) {
			struct zone *zone = &pgdat->node_zones[zoneid];
			if (!populated_zone(zone))
				continue;

			total += zone->present_pages;
			reserved += zone->present_pages - zone_managed_pages(zone);

			if (is_highmem_idx(zoneid))
				highmem += zone->present_pages;
		}
	}

	printk("%lu pages RAM\n", total);
	printk("%lu pages HighMem/MovableOnly\n", highmem);
	printk("%lu pages reserved\n", reserved);
#ifdef CONFIG_CMA
	printk("%lu pages cma reserved\n", totalcma_pages);
#endif
#ifdef CONFIG_MEMORY_FAILURE
	printk("%lu pages hwpoisoned\n", atomic_long_read(&num_poisoned_pages));
#endif
}
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