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arm64: fix SWP instruction emulation

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initial variable values may get overwritten
if they're listed as an output in ASM, even if
they're not explicitly written to.

Change-Id: I2a239e1819850a2a7005a46e83d82deac4ca303b
Signed-off-by: Rich Wiley <rwiley@nvidia.com>
Reviewed-on: http://git-master/r/379646
Reviewed-by: Automatic_Commit_Validation_User
Reviewed-by: Li Li (SW-TEGRA) <lli5@nvidia.com>
Tested-by: Li Li (SW-TEGRA) <lli5@nvidia.com>
GVS: Gerrit_Virtual_Submit
Reviewed-by: Alexander Van Brunt <avanbrunt@nvidia.com>
This commit is contained in:
Rich Wiley
2014-03-10 14:01:06 -07:00
committed by Greg Hackmann
parent 70f16b592e
commit ff5878c391
1 changed files with 5 additions and 3 deletions
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8
arch/arm64/kernel/swp_emulate.c
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@@ -40,12 +40,13 @@ static int swpb(u8 in, u8 *out, u8 *addr)
{
u8 _out;
int res;
int err = 0;
int err;
do {
__asm__ __volatile__(
"0: ldxrb %w1, %4\n"
"1: stxrb %w0, %w3, %4\n"
" mov %w2, #0\n"
"2:\n"
" .section .fixup,\"ax\"\n"
" .align 2\n"
@@ -58,7 +59,7 @@ static int swpb(u8 in, u8 *out, u8 *addr)
" .quad 1b, 3b\n"
" .previous"
: "=&r" (res), "=r" (_out), "=r" (err)
: "r" (in), "Q" (addr), "i" (-EFAULT)
: "r" (in), "Q" (*addr), "i" (-EFAULT)
: "cc", "memory");
} while (err == 0 && res != 0);
@@ -77,6 +78,7 @@ static int swp(u32 in, u32 *out, u32 *addr)
__asm__ __volatile__(
"0: ldxr %w1, %4\n"
"1: stxr %w0, %w3, %4\n"
" mov %w2, #0\n"
"2:\n"
" .section .fixup,\"ax\"\n"
" .align 2\n"
@@ -89,7 +91,7 @@ static int swp(u32 in, u32 *out, u32 *addr)
" .quad 1b, 3b\n"
" .previous"
: "=&r" (res), "=r" (_out), "=r" (err)
: "r" (in), "Q" (addr), "i" (-EFAULT)
: "r" (in), "Q" (*addr), "i" (-EFAULT)
: "cc", "memory");
} while (err == 0 && res != 0);