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authorWade Farnsworth <wfarnsworth@users.noreply.github.com>2019-04-18 06:47:58 -0700
committerGitHub <noreply@github.com>2019-04-18 06:47:58 -0700
commit9e1e1da00d8ef569d83a7a742a734dbbf5e0bd13 (patch)
treecf90facb2437c1b36a1c4b989b01a27330fedb10 /common/recipes-kernel/linux/linux-yocto-4.9.21/0006-x86-speculation-Use-Indirect-Branch-Prediction-Barri.patch
parent32ccbdeb2a2c1e4d5a7d8b3c0ef38fe410b7542a (diff)
parent840fbeecd7b31f141e4cc3a054c09b6f7866a73c (diff)
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Merge pull request #629 from ArsalanHAwan/merge-sumo
Merge sumo into master
Diffstat (limited to 'common/recipes-kernel/linux/linux-yocto-4.9.21/0006-x86-speculation-Use-Indirect-Branch-Prediction-Barri.patch')
-rw-r--r--common/recipes-kernel/linux/linux-yocto-4.9.21/0006-x86-speculation-Use-Indirect-Branch-Prediction-Barri.patch129
1 files changed, 0 insertions, 129 deletions
diff --git a/common/recipes-kernel/linux/linux-yocto-4.9.21/0006-x86-speculation-Use-Indirect-Branch-Prediction-Barri.patch b/common/recipes-kernel/linux/linux-yocto-4.9.21/0006-x86-speculation-Use-Indirect-Branch-Prediction-Barri.patch
deleted file mode 100644
index 90877ac8..00000000
--- a/common/recipes-kernel/linux/linux-yocto-4.9.21/0006-x86-speculation-Use-Indirect-Branch-Prediction-Barri.patch
+++ /dev/null
@@ -1,129 +0,0 @@
-From b3ad1b7521b3f4aaddc02e93ce3835bcac48da35 Mon Sep 17 00:00:00 2001
-From: Tim Chen <tim.c.chen@linux.intel.com>
-Date: Mon, 29 Jan 2018 22:04:47 +0000
-Subject: [PATCH 06/14] x86/speculation: Use Indirect Branch Prediction Barrier
- in context switch
-MIME-Version: 1.0
-Content-Type: text/plain; charset=UTF-8
-Content-Transfer-Encoding: 8bit
-
-commit 18bf3c3ea8ece8f03b6fc58508f2dfd23c7711c7 upstream.
-
-Flush indirect branches when switching into a process that marked itself
-non dumpable. This protects high value processes like gpg better,
-without having too high performance overhead.
-
-If done naïvely, we could switch to a kernel idle thread and then back
-to the original process, such as:
-
- process A -> idle -> process A
-
-In such scenario, we do not have to do IBPB here even though the process
-is non-dumpable, as we are switching back to the same process after a
-hiatus.
-
-To avoid the redundant IBPB, which is expensive, we track the last mm
-user context ID. The cost is to have an extra u64 mm context id to track
-the last mm we were using before switching to the init_mm used by idle.
-Avoiding the extra IBPB is probably worth the extra memory for this
-common scenario.
-
-For those cases where tlb_defer_switch_to_init_mm() returns true (non
-PCID), lazy tlb will defer switch to init_mm, so we will not be changing
-the mm for the process A -> idle -> process A switch. So IBPB will be
-skipped for this case.
-
-Thanks to the reviewers and Andy Lutomirski for the suggestion of
-using ctx_id which got rid of the problem of mm pointer recycling.
-
-Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
-Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
-Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
-Cc: ak@linux.intel.com
-Cc: karahmed@amazon.de
-Cc: arjan@linux.intel.com
-Cc: torvalds@linux-foundation.org
-Cc: linux@dominikbrodowski.net
-Cc: peterz@infradead.org
-Cc: bp@alien8.de
-Cc: luto@kernel.org
-Cc: pbonzini@redhat.com
-Link: https://lkml.kernel.org/r/1517263487-3708-1-git-send-email-dwmw@amazon.co.uk
-Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
----
- arch/x86/include/asm/tlbflush.h | 2 ++
- arch/x86/mm/tlb.c | 31 +++++++++++++++++++++++++++++++
- 2 files changed, 33 insertions(+)
-
-diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h
-index 94146f6..99185a0 100644
---- a/arch/x86/include/asm/tlbflush.h
-+++ b/arch/x86/include/asm/tlbflush.h
-@@ -68,6 +68,8 @@ static inline void invpcid_flush_all_nonglobals(void)
- struct tlb_state {
- struct mm_struct *active_mm;
- int state;
-+ /* last user mm's ctx id */
-+ u64 last_ctx_id;
-
- /*
- * Access to this CR4 shadow and to H/W CR4 is protected by
-diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
-index 146e842..b1bf41b 100644
---- a/arch/x86/mm/tlb.c
-+++ b/arch/x86/mm/tlb.c
-@@ -10,6 +10,7 @@
-
- #include <asm/tlbflush.h>
- #include <asm/mmu_context.h>
-+#include <asm/nospec-branch.h>
- #include <asm/cache.h>
- #include <asm/apic.h>
- #include <asm/uv/uv.h>
-@@ -106,6 +107,28 @@ void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next,
- unsigned cpu = smp_processor_id();
-
- if (likely(prev != next)) {
-+ u64 last_ctx_id = this_cpu_read(cpu_tlbstate.last_ctx_id);
-+
-+ /*
-+ * Avoid user/user BTB poisoning by flushing the branch
-+ * predictor when switching between processes. This stops
-+ * one process from doing Spectre-v2 attacks on another.
-+ *
-+ * As an optimization, flush indirect branches only when
-+ * switching into processes that disable dumping. This
-+ * protects high value processes like gpg, without having
-+ * too high performance overhead. IBPB is *expensive*!
-+ *
-+ * This will not flush branches when switching into kernel
-+ * threads. It will also not flush if we switch to idle
-+ * thread and back to the same process. It will flush if we
-+ * switch to a different non-dumpable process.
-+ */
-+ if (tsk && tsk->mm &&
-+ tsk->mm->context.ctx_id != last_ctx_id &&
-+ get_dumpable(tsk->mm) != SUID_DUMP_USER)
-+ indirect_branch_prediction_barrier();
-+
- if (IS_ENABLED(CONFIG_VMAP_STACK)) {
- /*
- * If our current stack is in vmalloc space and isn't
-@@ -120,6 +143,14 @@ void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next,
- set_pgd(pgd, init_mm.pgd[stack_pgd_index]);
- }
-
-+ /*
-+ * Record last user mm's context id, so we can avoid
-+ * flushing branch buffer with IBPB if we switch back
-+ * to the same user.
-+ */
-+ if (next != &init_mm)
-+ this_cpu_write(cpu_tlbstate.last_ctx_id, next->context.ctx_id);
-+
- this_cpu_write(cpu_tlbstate.state, TLBSTATE_OK);
- this_cpu_write(cpu_tlbstate.active_mm, next);
-
---
-2.7.4
-