[Xen-devel] [PATCH v8 01/11] arm: traps: use only least 32 bits of fid in PSCI handler

[Volodymyr Babchuk <volodymyr_babchuk@xxxxxxxx>]

According to SMCCC (ARM DEN 0028B, page 12), function id is
stored in least 32 bits of r0/x0 register:

    The least significant 32-bits are used, and the most significant
    32-bits are zero.

Signed-off-by: Volodymyr Babchuk <volodymyr_babchuk@xxxxxxxx>
Acked-by: Julien Grall <julien.grall@xxxxxxx>
---

* Removed part of the quote from ARM DEN 0028B due to typo.

* This patch needs to be backported

---
xen/arch/arm/traps.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/xen/arch/arm/traps.c b/xen/arch/arm/traps.c
index 701fdc8..0cff83e 100644
--- a/xen/arch/arm/traps.c
+++ b/xen/arch/arm/traps.c
@@ -1463,14 +1463,14 @@ static void do_debug_trap(struct cpu_user_regs *regs, 
unsigned int code)
 #endif
 
 /* helper function for checking arm mode 32/64 bit */
-static inline int psci_mode_check(struct domain *d, register_t fid)
+static inline int psci_mode_check(struct domain *d, uint32_t fid)
 {
         return !( is_64bit_domain(d)^( (fid & PSCI_0_2_64BIT) >> 30 ) );
 }
 
 static void do_trap_psci(struct cpu_user_regs *regs)
 {
-    register_t fid = PSCI_ARG(regs,0);
+    uint32_t fid = PSCI_ARG32(regs,0);
 
     /* preloading in case psci_mode_check fails */
     PSCI_RESULT_REG(regs) = PSCI_INVALID_PARAMETERS;
-- 
2.7.4


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