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From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	stable@vger.kernel.org, Ben Hutchings <ben@decadent.org.uk>,
	"Peter Zijlstra (Intel)" <peterz@infradead.org>
Subject: [PATCH 5.10 03/37] x86/nospec: Fix i386 RSB stuffing
Date: Fri,  2 Sep 2022 14:19:25 +0200	[thread overview]
Message-ID: <20220902121359.280247994@linuxfoundation.org> (raw)
In-Reply-To: <20220902121359.177846782@linuxfoundation.org>

From: Peter Zijlstra <peterz@infradead.org>

commit 332924973725e8cdcc783c175f68cf7e162cb9e5 upstream.

Turns out that i386 doesn't unconditionally have LFENCE, as such the
loop in __FILL_RETURN_BUFFER isn't actually speculation safe on such
chips.

Fixes: ba6e31af2be9 ("x86/speculation: Add LFENCE to RSB fill sequence")
Reported-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/Yv9tj9vbQ9nNlXoY@worktop.programming.kicks-ass.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 arch/x86/include/asm/nospec-branch.h |   12 ++++++++++++
 1 file changed, 12 insertions(+)

--- a/arch/x86/include/asm/nospec-branch.h
+++ b/arch/x86/include/asm/nospec-branch.h
@@ -50,6 +50,7 @@
  * the optimal version — two calls, each with their own speculation
  * trap should their return address end up getting used, in a loop.
  */
+#ifdef CONFIG_X86_64
 #define __FILL_RETURN_BUFFER(reg, nr)			\
 	mov	$(nr/2), reg;				\
 771:							\
@@ -60,6 +61,17 @@
 	jnz	771b;					\
 	/* barrier for jnz misprediction */		\
 	lfence;
+#else
+/*
+ * i386 doesn't unconditionally have LFENCE, as such it can't
+ * do a loop.
+ */
+#define __FILL_RETURN_BUFFER(reg, nr)			\
+	.rept nr;					\
+	__FILL_RETURN_SLOT;				\
+	.endr;						\
+	add	$(BITS_PER_LONG/8) * nr, %_ASM_SP;
+#endif
 
 /*
  * Stuff a single RSB slot.



  parent reply	other threads:[~2022-09-02 13:00 UTC|newest]

Thread overview: 46+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-09-02 12:19 [PATCH 5.10 00/37] 5.10.141-rc1 review Greg Kroah-Hartman
2022-09-02 12:19 ` [PATCH 5.10 01/37] mm: Force TLB flush for PFNMAP mappings before unlink_file_vma() Greg Kroah-Hartman
2022-09-02 12:19 ` [PATCH 5.10 02/37] x86/nospec: Unwreck the RSB stuffing Greg Kroah-Hartman
2022-09-02 12:19 ` Greg Kroah-Hartman [this message]
2022-09-02 12:19 ` [PATCH 5.10 04/37] crypto: lib - remove unneeded selection of XOR_BLOCKS Greg Kroah-Hartman
2022-09-02 12:19 ` [PATCH 5.10 05/37] s390/mm: do not trigger write fault when vma does not allow VM_WRITE Greg Kroah-Hartman
2022-09-02 12:19 ` [PATCH 5.10 06/37] kbuild: Fix include path in scripts/Makefile.modpost Greg Kroah-Hartman
2022-09-02 12:19 ` [PATCH 5.10 07/37] Bluetooth: L2CAP: Fix build errors in some archs Greg Kroah-Hartman
2022-09-02 12:19 ` [PATCH 5.10 08/37] Revert "PCI/portdrv: Dont disable AER reporting in get_port_device_capability()" Greg Kroah-Hartman
2022-09-02 12:19 ` [PATCH 5.10 09/37] HID: steam: Prevent NULL pointer dereference in steam_{recv,send}_report Greg Kroah-Hartman
2022-09-02 12:19 ` [PATCH 5.10 10/37] udmabuf: Set the DMA mask for the udmabuf device (v2) Greg Kroah-Hartman
2022-09-02 12:19 ` [PATCH 5.10 11/37] media: pvrusb2: fix memory leak in pvr_probe Greg Kroah-Hartman
2022-09-02 12:19 ` [PATCH 5.10 12/37] HID: hidraw: fix memory leak in hidraw_release() Greg Kroah-Hartman
2022-09-02 12:19 ` [PATCH 5.10 13/37] net: fix refcount bug in sk_psock_get (2) Greg Kroah-Hartman
2022-09-02 12:19 ` [PATCH 5.10 14/37] fbdev: fb_pm2fb: Avoid potential divide by zero error Greg Kroah-Hartman
2022-09-02 12:19 ` [PATCH 5.10 15/37] ftrace: Fix NULL pointer dereference in is_ftrace_trampoline when ftrace is dead Greg Kroah-Hartman
2022-09-02 12:19 ` [PATCH 5.10 16/37] bpf: Dont redirect packets with invalid pkt_len Greg Kroah-Hartman
2022-09-02 12:19 ` [PATCH 5.10 17/37] mm/rmap: Fix anon_vma->degree ambiguity leading to double-reuse Greg Kroah-Hartman
2022-09-02 12:19 ` [PATCH 5.10 18/37] mmc: mtk-sd: Clear interrupts when cqe off/disable Greg Kroah-Hartman
2022-09-02 12:19 ` [PATCH 5.10 19/37] drm/amd/display: Avoid MPC infinite loop Greg Kroah-Hartman
2022-09-02 12:19 ` [PATCH 5.10 20/37] drm/amd/display: For stereo keep "FLIP_ANY_FRAME" Greg Kroah-Hartman
2022-09-02 12:19 ` [PATCH 5.10 21/37] drm/amd/display: clear optc underflow before turn off odm clock Greg Kroah-Hartman
2022-09-02 12:19 ` [PATCH 5.10 22/37] neigh: fix possible DoS due to net iface start/stop loop Greg Kroah-Hartman
2022-09-02 12:19 ` [PATCH 5.10 23/37] s390/hypfs: avoid error message under KVM Greg Kroah-Hartman
2022-09-02 12:19 ` [PATCH 5.10 24/37] drm/amd/pm: add missing ->fini_microcode interface for Sienna Cichlid Greg Kroah-Hartman
2022-09-02 12:19 ` [PATCH 5.10 25/37] drm/amd/display: Fix pixel clock programming Greg Kroah-Hartman
2022-09-02 12:19 ` [PATCH 5.10 26/37] drm/amdgpu: Increase tlb flush timeout for sriov Greg Kroah-Hartman
2022-09-02 12:19 ` [PATCH 5.10 27/37] netfilter: conntrack: NF_CONNTRACK_PROCFS should no longer default to y Greg Kroah-Hartman
2022-09-02 12:19 ` [PATCH 5.10 28/37] lib/vdso: Mark do_hres_timens() and do_coarse_timens() __always_inline() Greg Kroah-Hartman
2022-09-02 12:19 ` [PATCH 5.10 29/37] kprobes: dont call disarm_kprobe() for disabled kprobes Greg Kroah-Hartman
2022-09-02 12:19 ` [PATCH 5.10 30/37] io_uring: disable polling pollfree files Greg Kroah-Hartman
2022-09-02 12:19 ` [PATCH 5.10 31/37] xfs: remove infinite loop when reserving free block pool Greg Kroah-Hartman
2022-09-02 12:19 ` [PATCH 5.10 32/37] xfs: always succeed at setting the reserve pool size Greg Kroah-Hartman
2022-09-02 12:19 ` [PATCH 5.10 33/37] xfs: fix overfilling of reserve pool Greg Kroah-Hartman
2022-09-02 12:19 ` [PATCH 5.10 34/37] xfs: fix soft lockup via spinning in filestream ag selection loop Greg Kroah-Hartman
2022-09-02 12:19 ` [PATCH 5.10 35/37] xfs: revert "xfs: actually bump warning counts when we send warnings" Greg Kroah-Hartman
2022-09-02 12:19 ` [PATCH 5.10 36/37] net/af_packet: check len when min_header_len equals to 0 Greg Kroah-Hartman
2022-09-02 12:19 ` [PATCH 5.10 37/37] net: neigh: dont call kfree_skb() under spin_lock_irqsave() Greg Kroah-Hartman
2022-09-02 16:36 ` [PATCH 5.10 00/37] 5.10.141-rc1 review Jon Hunter
2022-09-02 17:36 ` Florian Fainelli
2022-09-02 22:16 ` Shuah Khan
2022-09-03  0:36 ` Guenter Roeck
2022-09-03  3:15 ` Rudi Heitbaum
2022-09-03  6:06 ` Naresh Kamboju
2022-09-03 10:43 ` Sudip Mukherjee
2022-09-05  7:44 ` Pavel Machek

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