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Subject[RFC PATCH 3/4] arm64: implement nospec_{load,ptr}()
Date
This patch implements nospec_load() and nospec_ptr() for arm64,
following the recommended architectural sequence.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
---
arch/arm64/include/asm/barrier.h | 61 ++++++++++++++++++++++++++++++++++++++++
1 file changed, 61 insertions(+)

diff --git a/arch/arm64/include/asm/barrier.h b/arch/arm64/include/asm/barrier.h
index 77651c49ef44..5d17919e2688 100644
--- a/arch/arm64/include/asm/barrier.h
+++ b/arch/arm64/include/asm/barrier.h
@@ -40,6 +40,67 @@
#define dma_rmb() dmb(oshld)
#define dma_wmb() dmb(oshst)

+#define __load_no_speculate_n(ptr, lo, hi, failval, cmpptr, w, sz) \
+({ \
+ typeof(*ptr) __nln_val; \
+ typeof(*ptr) __failval = \
+ (typeof(*ptr))(unsigned long)(failval); \
+ \
+ asm volatile ( \
+ " cmp %[c], %[l]\n" \
+ " ccmp %[c], %[h], 2, cs\n" \
+ " b.cs 1f\n" \
+ " ldr" #sz " %" #w "[v], %[p]\n" \
+ "1: csel %" #w "[v], %" #w "[v], %" #w "[f], cc\n" \
+ " hint #0x14 // CSDB\n" \
+ : [v] "=&r" (__nln_val) \
+ : [p] "m" (*(ptr)), [l] "r" (lo), [h] "r" (hi), \
+ [f] "rZ" (__failval), [c] "r" (cmpptr) \
+ : "cc"); \
+ \
+ __nln_val; \
+})
+
+#define __load_no_speculate(ptr, lo, hi, failval, cmpptr) \
+({ \
+ typeof(*(ptr)) __nl_val; \
+ \
+ switch (sizeof(__nl_val)) { \
+ case 1: \
+ __nl_val = __load_no_speculate_n(ptr, lo, hi, failval, \
+ cmpptr, w, b); \
+ break; \
+ case 2: \
+ __nl_val = __load_no_speculate_n(ptr, lo, hi, failval, \
+ cmpptr, w, h); \
+ break; \
+ case 4: \
+ __nl_val = __load_no_speculate_n(ptr, lo, hi, failval, \
+ cmpptr, w, ); \
+ break; \
+ case 8: \
+ __nl_val = __load_no_speculate_n(ptr, lo, hi, failval, \
+ cmpptr, x, ); \
+ break; \
+ default: \
+ BUILD_BUG(); \
+ } \
+ \
+ __nl_val; \
+})
+
+#define nospec_load(ptr, lo, hi) \
+({ \
+ typeof(ptr) __nl_ptr = (ptr); \
+ __load_no_speculate(__nl_ptr, lo, hi, 0, __nl_ptr); \
+})
+
+#define nospec_ptr(ptr, lo, hi) \
+({ \
+ typeof(ptr) __np_ptr = (ptr); \
+ __load_no_speculate(&__np_ptr, lo, hi, 0, __np_ptr); \
+})
+
#define __smp_mb() dmb(ish)
#define __smp_rmb() dmb(ishld)
#define __smp_wmb() dmb(ishst)
--
2.11.0
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