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c3ee82ce47
The KASAN subsystem wraps calls to memcpy(), memset() and memmove() to sanitize the arguments before invoking the actual routines, which have been renamed to __memcpy(), __memset() and __memmove(), respectively. When CONFIG_KASAN is enabled for the kernel build but KASAN code generation is disabled for the compilation unit (which is needed for things like the EFI stub or the decompressor), the string routines are just #define'd to their __ prefixed names so that they are simply invoked directly. This does however rely on those __ prefixed names to exist in the symbol namespace, which is not currently the case for the x86 decompressor, which may lead to errors like drivers/firmware/efi/libstub/tpm.o: In function `efi_retrieve_tpm2_eventlog': tpm.c:(.text+0x2a8): undefined reference to `__memcpy' So let's expose the __ prefixed symbols in the decompressor when KASAN is enabled. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Acked-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> Cc: Andrey Konovalov <andreyknvl@google.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Matthew Garrett <matthewgarrett@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-efi@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
81 lines
1.9 KiB
C
81 lines
1.9 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* This provides an optimized implementation of memcpy, and a simplified
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* implementation of memset and memmove. These are used here because the
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* standard kernel runtime versions are not yet available and we don't
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* trust the gcc built-in implementations as they may do unexpected things
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* (e.g. FPU ops) in the minimal decompression stub execution environment.
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*/
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#include "error.h"
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#include "../string.c"
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#ifdef CONFIG_X86_32
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static void *____memcpy(void *dest, const void *src, size_t n)
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{
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int d0, d1, d2;
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asm volatile(
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"rep ; movsl\n\t"
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"movl %4,%%ecx\n\t"
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"rep ; movsb\n\t"
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: "=&c" (d0), "=&D" (d1), "=&S" (d2)
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: "0" (n >> 2), "g" (n & 3), "1" (dest), "2" (src)
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: "memory");
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return dest;
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}
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#else
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static void *____memcpy(void *dest, const void *src, size_t n)
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{
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long d0, d1, d2;
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asm volatile(
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"rep ; movsq\n\t"
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"movq %4,%%rcx\n\t"
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"rep ; movsb\n\t"
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: "=&c" (d0), "=&D" (d1), "=&S" (d2)
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: "0" (n >> 3), "g" (n & 7), "1" (dest), "2" (src)
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: "memory");
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return dest;
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}
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#endif
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void *memset(void *s, int c, size_t n)
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{
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int i;
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char *ss = s;
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for (i = 0; i < n; i++)
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ss[i] = c;
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return s;
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}
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void *memmove(void *dest, const void *src, size_t n)
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{
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unsigned char *d = dest;
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const unsigned char *s = src;
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if (d <= s || d - s >= n)
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return ____memcpy(dest, src, n);
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while (n-- > 0)
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d[n] = s[n];
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return dest;
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}
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/* Detect and warn about potential overlaps, but handle them with memmove. */
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void *memcpy(void *dest, const void *src, size_t n)
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{
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if (dest > src && dest - src < n) {
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warn("Avoiding potentially unsafe overlapping memcpy()!");
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return memmove(dest, src, n);
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}
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return ____memcpy(dest, src, n);
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}
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#ifdef CONFIG_KASAN
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extern void *__memset(void *s, int c, size_t n) __alias(memset);
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extern void *__memmove(void *dest, const void *src, size_t n) __alias(memmove);
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extern void *__memcpy(void *dest, const void *src, size_t n) __alias(memcpy);
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#endif
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