Allow loading a pair of u32 within a rseq critical section. It can be
used in situations where both rseq_abi()->mm_cid and
rseq_abi()->node_id need to be sampled atomically with respect to
preemption, signal delivery and migration.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx>
Cc: linux-kselftest@xxxxxxxxxxxxxxx
---
tools/testing/selftests/rseq/rseq-x86-bits.h | 43 ++++++++++++++++++++
tools/testing/selftests/rseq/rseq.h | 14 +++++++
2 files changed, 57 insertions(+)
diff --git a/tools/testing/selftests/rseq/rseq-x86-bits.h b/tools/testing/selftests/rseq/rseq-x86-bits.h
index 8a9431eec467..fdf5ef398393 100644
--- a/tools/testing/selftests/rseq/rseq-x86-bits.h
+++ b/tools/testing/selftests/rseq/rseq-x86-bits.h
@@ -990,4 +990,47 @@ int RSEQ_TEMPLATE_IDENTIFIER(rseq_cmpeqv_trymemcpy_storev)(intptr_t *v, intptr_t
#endif
+#if defined(RSEQ_TEMPLATE_CPU_ID_NONE) && defined(RSEQ_TEMPLATE_MO_RELAXED)
+
+#define RSEQ_ARCH_HAS_LOAD_U32_U32
+
+static inline __attribute__((always_inline))
+int RSEQ_TEMPLATE_IDENTIFIER(rseq_load_u32_u32)(uint32_t *dst1, uint32_t *src1,
+ uint32_t *dst2, uint32_t *src2)
+{
+ RSEQ_INJECT_C(9)
+
+ __asm__ __volatile__ goto (
+ RSEQ_ASM_DEFINE_TABLE(3, 1f, 2f, 4f) /* start, commit, abort */
+ /* Start rseq by storing table entry pointer into rseq_cs. */
+ RSEQ_ASM_STORE_RSEQ_CS(1, 3b, RSEQ_ASM_TP_SEGMENT:RSEQ_CS_OFFSET(%[rseq_offset]))
+ RSEQ_INJECT_ASM(3)
+ "movl %[src1], %%eax\n\t"
+ "movl %%eax, %[dst1]\n\t"
+ "movl %[src2], %%eax\n\t"
+ "movl %%eax, %[dst2]\n\t"
+ "2:\n\t"
+ RSEQ_INJECT_ASM(4)
+ RSEQ_ASM_DEFINE_ABORT(4, "", abort)
+ : /* gcc asm goto does not allow outputs */
+ : [rseq_offset] "r" (rseq_offset),
+ /* final store input */
+ [dst1] "m" (*dst1),
+ [src1] "m" (*src1),
+ [dst2] "m" (*dst2),
+ [src2] "m" (*src2)
+ : "memory", "cc", "rax"
+ RSEQ_INJECT_CLOBBER
+ : abort
+ );
+ rseq_after_asm_goto();
+ return 0;
+abort:
+ rseq_after_asm_goto();
+ RSEQ_INJECT_FAILED
+ return -1;
+}
+
+#endif /* defined(RSEQ_TEMPLATE_CPU_ID_NONE) && defined(RSEQ_TEMPLATE_MO_RELAXED) */
+
#include "rseq-bits-reset.h"
diff --git a/tools/testing/selftests/rseq/rseq.h b/tools/testing/selftests/rseq/rseq.h
index d7364ea4d201..b6095c2a5da6 100644
--- a/tools/testing/selftests/rseq/rseq.h
+++ b/tools/testing/selftests/rseq/rseq.h
@@ -381,4 +381,18 @@ int rseq_cmpeqv_trymemcpy_storev(enum rseq_mo rseq_mo, enum rseq_percpu_mode per
}
}
+#ifdef RSEQ_ARCH_HAS_LOAD_U32_U32
+
+static inline __attribute__((always_inline))
+int rseq_load_u32_u32(enum rseq_mo rseq_mo,
+ uint32_t *dst1, uint32_t *src1,
+ uint32_t *dst2, uint32_t *src2)
+{
+ if (rseq_mo != RSEQ_MO_RELAXED)
+ return -1;
+ return rseq_load_u32_u32_relaxed(dst1, src1, dst2, src2);
+}
+
+#endif
+
#endif /* RSEQ_H_ */
--
2.39.2
