x86, realmode: Pointer walk cleanups, pull out invariant use of __pa() (7306006f) · Commits · 戴 / test

The pointer arithmetic in this function was really bizarre, where in fact all we really wanted was a simple pointer array walk. Use the much more idiomatic construction for that (*ptr++). Factor an invariant use of __pa() out of the relocation loop. At least on 64 bits it seems gcc isn't capable of doing that automatically. Change the scope of a couple of variables to make it extra obvious that they are extremely local temp variables. Signed-off-by:

H. Peter Anvin <hpa@linux.intel.com> Link: http://lkml.kernel.org/n/tip-rd908t9c8kvcojdabtmm94mb@git.kernel.org

arch/x86/realmode/init.c

+12 −14

Original line number	Diff line number	Diff line
		@@ -29,12 +29,10 @@ void __init reserve_real_mode(void)
		void __init setup_real_mode(void)
		{
		u16 real_mode_seg;
		u32 *rel;
		const u32 *rel;
		u32 count;
		u32 *ptr;
		u16 *seg;
		int i;
		unsigned char *base;
		unsigned long phys_base;
		struct trampoline_header *trampoline_header;
		size_t size = PAGE_ALIGN(real_mode_blob_end - real_mode_blob);
		#ifdef CONFIG_X86_64
		@@ -46,23 +44,23 @@ void __init setup_real_mode(void)

		memcpy(base, real_mode_blob, size);

		real_mode_seg = __pa(base) >> 4;
		phys_base = __pa(base);
		real_mode_seg = phys_base >> 4;

		rel = (u32 *) real_mode_relocs;

		/* 16-bit segment relocations. */
		count = rel[0];
		rel = &rel[1];
		for (i = 0; i < count; i++) {
		seg = (u16 *) (base + rel[i]);
		count = *rel++;
		while (count--) {
		u16 seg = (u16 ) (base + *rel++);
		*seg = real_mode_seg;
		}

		/* 32-bit linear relocations. */
		count = rel[i];
		rel = &rel[i + 1];
		for (i = 0; i < count; i++) {
		ptr = (u32 *) (base + rel[i]);
		*ptr += __pa(base);
		count = *rel++;
		while (count--) {
		u32 ptr = (u32 ) (base + *rel++);
		*ptr += phys_base;
		}

		/* Must be perfomed after relocation. */

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