Stephen Rothwell's compiler did something amazing: it unrolled a
loop, discovered that one iteration of that loop contained an
always-true test, and emitted a warning that will IMO only serve to
convince people to disable the warning.
That bogus warning caused me to wonder what prompted such an
absurdity from his compiler, and I discovered that the code in
question was, in fact, completely wrong -- I was looking things up
in the wrong array.
This affects 3.16 as well, but the only effect is to screw up the
error checking a bit. vdso2c's output is unaffected.
Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
---
arch/x86/vdso/vdso2c.h | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/arch/x86/vdso/vdso2c.h b/arch/x86/vdso/vdso2c.h
index fd57829..0224987 100644
--- a/arch/x86/vdso/vdso2c.h
+++ b/arch/x86/vdso/vdso2c.h
@@ -109,16 +109,18 @@ static void BITSFUNC(go)(void *raw_addr, size_t raw_len,
/* Validate mapping addresses. */
for (i = 0; i < sizeof(special_pages) / sizeof(special_pages[0]); i++) {
- if (!syms[i])
+ INT_BITS symval = syms[special_pages[i]];
+
+ if (!symval)
continue; /* The mapping isn't used; ignore it. */
- if (syms[i] % 4096)
+ if (symval % 4096)
fail("%s must be a multiple of 4096\n",
required_syms[i].name);
- if (syms[sym_vvar_start] > syms[i] + 4096)
- fail("%s underruns begin_vvar\n",
+ if (symval + 4096 < syms[sym_vvar_start])
+ fail("%s underruns vvar_start\n",
required_syms[i].name);
- if (syms[i] + 4096 > 0)
+ if (symval + 4096 > 0)
fail("%s is on the wrong side of the vdso text\n",
required_syms[i].name);
}
--
1.9.3
--
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