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csm: Sanitise alignment constraint in Legacy16GetTableAddress 

The alignment constraint is defined in the CSM specifications as
"Bit mapped.  First non-zero bit from the right is the alignment."

Use __fls() to sanitise the alignment given that definition, since
passing a non-power-of-two alignment to _malloc() isn't going to work
well. And cope with being passed zero, which was happening for the
E820 table allocation from EDK2.

Signed-off-by: David Woodhouse <dwmw2@infradead.org>
This commit is contained in:
David Woodhouse 2019-06-13 16:25:13 +01:00 committed by Kevin O'Connor
parent 85137fb5f2
commit 6e56ed129c
1 changed files with 12 additions and 2 deletions
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14
src/fw/csm.c
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@ -258,11 +258,21 @@ handle_csm_0006(struct bregs *regs)
u16 region = regs->bx; // (1 for F000 seg, 2 for E000 seg, 0 for either)
void *chunk = NULL;
dprintf(3, "Legacy16GetTableAddress size %x align %x region %d\n",
size, align, region);
if (!region)
region = 3;
dprintf(3, "Legacy16GetTableAddress size %x align %x region %d\n",
size, align, region);
// DX = Required address alignment. Bit mapped.
// First non-zero bit from the right is the alignment.*/
if (align) {
align = 1 << __ffs(align);
if (align < MALLOC_MIN_ALIGN)
align = MALLOC_MIN_ALIGN;
} else {
align = MALLOC_MIN_ALIGN;
}
if (region & 2)
chunk = _malloc(&ZoneLow, size, align);