On 16.09.20 09:12, Oliver Schwartz wrote:
SMC calls may modify registers x0 to x3. To make sure the compiler doesn't
assume input registers to be constant, also mark these registers as output
when used as input.
Signed-off-by: Oliver Schwartz <[email protected]>
---
hypervisor/arch/arm64/include/asm/smc.h | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/hypervisor/arch/arm64/include/asm/smc.h
b/hypervisor/arch/arm64/include/asm/smc.h
index 1a5d5c8..e7b6723 100644
--- a/hypervisor/arch/arm64/include/asm/smc.h
+++ b/hypervisor/arch/arm64/include/asm/smc.h
@@ -28,7 +28,7 @@ static inline long smc_arg1(unsigned long id, unsigned long
par1)
register unsigned long __par1 asm("r1") = par1;
asm volatile ("smc #0\n\t"
- : "=r" (__id)
+ : "=r" (__id), "=r"(__par1)
: "r"(__id), "r"(__par1)
: "memory", "x2", "x3");
@@ -43,7 +43,7 @@ static inline long smc_arg2(unsigned long id, unsigned long par1,
register unsigned long __par2 asm("r2") = par2;
asm volatile ("smc #0\n\t"
- : "=r" (__id)
+ : "=r" (__id), "=r"(__par1), "=r"(__par2)
: "r"(__id), "r"(__par1), "r"(__par2)
: "memory", "x3");
@@ -62,7 +62,7 @@ static inline long smc_arg5(unsigned long id, unsigned long par1,
register unsigned long __par5 asm("r5") = par5;
asm volatile ("smc #0\n\t"
- : "=r" (__id)
+ : "=r" (__id), "=r"(__par1), "=r"(__par2), "=r"(__par3)
: "r"(__id), "r"(__par1), "r"(__par2), "r"(__par3),
"r"(__par4), "r"(__par5)
: "memory");
Good catch! We likely have the same issue with our hypercall interface
(jailhouse_hypercall.h).
We should probably look carefully again at how Linux expresses these
constraints: linux/include/linux/arm-smccc.h. That appears to me like we
need "+r" for input/output registers and "=&r" for those that are just
input but might be clobbered on return.
Jan
--
Siemens AG, Corporate Technology, CT RDA IOT SES-DE
Corporate Competence Center Embedded Linux
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