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MIPS: Avoid overoptimization by GCC. 

Without this, it's possible that LTO will discard the calls to
set_except_vector() in the probe for the DADDI overflow bug resulting in a
kernel crash like this:

 [...]
 Mount-cache hash table entries: 256
 Checking for the daddi bug... Integer overflow[#1]:
 Cpu 0
 $ 0   : 0000000000000000 0000000010008ce1 0000000000000001 0000000000000000
 $ 4   : 7fffffffffffedcd ffffffff81410000 0000000000000030 000000000000003f
 [...]

There are other similar places in the kernel so we've just been lucky
that GCC's been tolerant.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
hifive-unleashed-5.1
Ralf Baechle 2013-03-14 18:49:26 +01:00
parent 02b849f761
commit 1186e4e904
1 changed files with 1 additions and 2 deletions
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3
arch/mips/kernel/traps.c
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@ -1390,9 +1390,8 @@ unsigned long vi_handlers[64];
void __init *set_except_vector(int n, void *addr)
{
unsigned long handler = (unsigned long) addr;
unsigned long old_handler = exception_handlers[n];
unsigned long old_handler = xchg(&exception_handlers[n], handler);
exception_handlers[n] = handler;
if (n == 0 && cpu_has_divec) {
unsigned long jump_mask = ~((1 << 28) - 1);
u32 *buf = (u32 *)(ebase + 0x200);