From ec9c82e03a744e5698bd95eab872855861a821fa Mon Sep 17 00:00:00 2001 From: Mathieu Desnoyers Date: Mon, 9 Jul 2018 15:51:53 -0400 Subject: rseq: uapi: Declare rseq_cs field as union, update includes Declaring the rseq_cs field as a union between __u64 and two __u32 allows both 32-bit and 64-bit kernels to read the full __u64, and therefore validate that a 32-bit user-space cleared the upper 32 bits, thus ensuring a consistent behavior between native 32-bit kernels and 32-bit compat tasks on 64-bit kernels. Check that the rseq_cs value read is < TASK_SIZE. The asm/byteorder.h header needs to be included by rseq.h, now that it is not using linux/types_32_64.h anymore. Considering that only __32 and __u64 types are declared in linux/rseq.h, the linux/types.h header should always be included for both kernel and user-space code: including stdint.h is just for u64 and u32, which are not used in this header at all. Use copy_from_user()/clear_user() to interact with a 64-bit field, because arm32 does not implement 64-bit __get_user, and ppc32 does not 64-bit get_user. Considering that the rseq_cs pointer does not need to be loaded/stored with single-copy atomicity from the kernel anymore, we can simply use copy_from_user()/clear_user(). Signed-off-by: Mathieu Desnoyers Signed-off-by: Thomas Gleixner Cc: linux-api@vger.kernel.org Cc: Peter Zijlstra Cc: "Paul E . McKenney" Cc: Boqun Feng Cc: Andy Lutomirski Cc: Dave Watson Cc: Paul Turner Cc: Andrew Morton Cc: Russell King Cc: "H . Peter Anvin" Cc: Andi Kleen Cc: Chris Lameter Cc: Ben Maurer Cc: Steven Rostedt Cc: Josh Triplett Cc: Linus Torvalds Cc: Catalin Marinas Cc: Will Deacon Cc: Michael Kerrisk Cc: Joel Fernandes Cc: "Paul E. McKenney" Cc: "H. Peter Anvin" Link: https://lkml.kernel.org/r/20180709195155.7654-5-mathieu.desnoyers@efficios.com --- tools/testing/selftests/rseq/rseq.h | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) (limited to 'tools/testing') diff --git a/tools/testing/selftests/rseq/rseq.h b/tools/testing/selftests/rseq/rseq.h index a4684112676c..f2073cfa4448 100644 --- a/tools/testing/selftests/rseq/rseq.h +++ b/tools/testing/selftests/rseq/rseq.h @@ -133,6 +133,15 @@ static inline uint32_t rseq_current_cpu(void) return cpu; } +static inline void rseq_clear_rseq_cs(void) +{ +#ifdef __LP64__ + __rseq_abi.rseq_cs.ptr = 0; +#else + __rseq_abi.rseq_cs.ptr.ptr32 = 0; +#endif +} + /* * rseq_prepare_unload() should be invoked by each thread using rseq_finish*() * at least once between their last rseq_finish*() and library unload of the @@ -143,7 +152,7 @@ static inline uint32_t rseq_current_cpu(void) */ static inline void rseq_prepare_unload(void) { - __rseq_abi.rseq_cs = 0; + rseq_clear_rseq_cs(); } #endif /* RSEQ_H_ */ -- cgit v1.2.3 From 8a46580128a02bdc18d7dcc0cba19d3cea4fb9c4 Mon Sep 17 00:00:00 2001 From: Mathieu Desnoyers Date: Mon, 9 Jul 2018 15:51:55 -0400 Subject: rseq/selftests: cleanup: Update comment above rseq_prepare_unload rseq as it was merged does not have rseq_finish_*() in the user-space selftests anymore. Update the rseq_prepare_unload() helper comment to adapt to this reality. Signed-off-by: Mathieu Desnoyers Signed-off-by: Thomas Gleixner Cc: linux-api@vger.kernel.org Cc: Peter Zijlstra Cc: "Paul E . McKenney" Cc: Boqun Feng Cc: Andy Lutomirski Cc: Dave Watson Cc: Paul Turner Cc: Andrew Morton Cc: Russell King Cc: "H . Peter Anvin" Cc: Andi Kleen Cc: Chris Lameter Cc: Ben Maurer Cc: Steven Rostedt Cc: Josh Triplett Cc: Linus Torvalds Cc: Catalin Marinas Cc: Will Deacon Cc: Michael Kerrisk Cc: Joel Fernandes Cc: "Paul E. McKenney" Cc: "H. Peter Anvin" Link: https://lkml.kernel.org/r/20180709195155.7654-7-mathieu.desnoyers@efficios.com --- tools/testing/selftests/rseq/rseq.h | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) (limited to 'tools/testing') diff --git a/tools/testing/selftests/rseq/rseq.h b/tools/testing/selftests/rseq/rseq.h index f2073cfa4448..86ce22417e0d 100644 --- a/tools/testing/selftests/rseq/rseq.h +++ b/tools/testing/selftests/rseq/rseq.h @@ -143,12 +143,13 @@ static inline void rseq_clear_rseq_cs(void) } /* - * rseq_prepare_unload() should be invoked by each thread using rseq_finish*() - * at least once between their last rseq_finish*() and library unload of the - * library defining the rseq critical section (struct rseq_cs). This also - * applies to use of rseq in code generated by JIT: rseq_prepare_unload() - * should be invoked at least once by each thread using rseq_finish*() before - * reclaim of the memory holding the struct rseq_cs. + * rseq_prepare_unload() should be invoked by each thread executing a rseq + * critical section at least once between their last critical section and + * library unload of the library defining the rseq critical section + * (struct rseq_cs). This also applies to use of rseq in code generated by + * JIT: rseq_prepare_unload() should be invoked at least once by each + * thread executing a rseq critical section before reclaim of the memory + * holding the struct rseq_cs. */ static inline void rseq_prepare_unload(void) { -- cgit v1.2.3