From: Lai Jiangshan <jiangshanlai@gmail.com>
To: linux-kernel@vger.kernel.org
Cc: x86@kernel.org, Lai Jiangshan <laijs@linux.alibaba.com>,
Andy Lutomirski <luto@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
"H. Peter Anvin" <hpa@zytor.com>
Subject: [PATCH V5 02/50] x86/entry: Use the correct fence macro after swapgs in kernel CR3
Date: Wed, 10 Nov 2021 19:56:48 +0800 [thread overview]
Message-ID: <20211110115736.3776-3-jiangshanlai@gmail.com> (raw)
In-Reply-To: <20211110115736.3776-1-jiangshanlai@gmail.com>
From: Lai Jiangshan <laijs@linux.alibaba.com>
The commit c75890700455 ("x86/entry/64: Remove unneeded kernel CR3
switching") removes a CR3 write in the faulting path of load_gs_index.
But the path's FENCE_SWAPGS_USER_ENTRY has no fence operation if PTI
is enabled. Rahter, it depends on the CR3 write of SWITCH_TO_KERNEL_CR3.
So the path should use FENCE_SWAPGS_KERNEL_ENTRY if SWITCH_TO_KERNEL_CR3
is removed.
Fixes: c75890700455 ("x86/entry/64: Remove unneeded kernel CR3 switching")
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
---
arch/x86/entry/entry_64.S | 16 +++++++++-------
1 file changed, 9 insertions(+), 7 deletions(-)
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 14ffe12807ba..6189a0dc83ab 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -993,11 +993,6 @@ SYM_CODE_START_LOCAL(error_entry)
pushq %r12
ret
-.Lerror_entry_done_lfence:
- FENCE_SWAPGS_KERNEL_ENTRY
-.Lerror_entry_done:
- ret
-
/*
* There are two places in the kernel that can potentially fault with
* usergs. Handle them here. B stepping K8s sometimes report a
@@ -1020,8 +1015,15 @@ SYM_CODE_START_LOCAL(error_entry)
* .Lgs_change's error handler with kernel gsbase.
*/
SWAPGS
- FENCE_SWAPGS_USER_ENTRY
- jmp .Lerror_entry_done
+
+ /*
+ * The above code has no serializing instruction. So do an lfence
+ * to prevent GS speculation, regardless of whether it is kernel
+ * gsbase or user gsbase.
+ */
+.Lerror_entry_done_lfence:
+ FENCE_SWAPGS_KERNEL_ENTRY
+ ret
.Lbstep_iret:
/* Fix truncated RIP */
--
2.19.1.6.gb485710b
next prev parent reply other threads:[~2021-11-10 11:57 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-10 11:56 [PATCH V5 00/50] x86/entry/64: Convert a bunch of ASM entry code into C code Lai Jiangshan
2021-11-10 11:56 ` [PATCH V5 01/50] x86/entry: Add fence for kernel entry swapgs in paranoid_entry() Lai Jiangshan
2021-11-18 15:54 ` Peter Zijlstra
2021-11-18 17:27 ` Lai Jiangshan
2021-11-10 11:56 ` Lai Jiangshan [this message]
2021-11-10 11:56 ` [PATCH V5 03/50] x86/traps: Remove stack-protector from traps.c Lai Jiangshan
2021-11-18 19:55 ` Peter Zijlstra
2021-11-19 1:38 ` Lai Jiangshan
2021-11-10 11:56 ` [PATCH V5 04/50] x86/xen: Add xenpv_restore_regs_and_return_to_usermode() Lai Jiangshan
2021-11-10 11:56 ` [PATCH V5 05/50] x86/entry: Use swapgs and native_iret directly in swapgs_restore_regs_and_return_to_usermode Lai Jiangshan
2021-11-10 11:56 ` [PATCH V5 06/50] compiler_types.h: Add __noinstr_section() for noinstr Lai Jiangshan
2021-11-10 11:56 ` [PATCH V5 07/50] x86/entry: Introduce __entry_text for entry code written in C Lai Jiangshan
2021-11-10 11:56 ` [PATCH V5 08/50] x86/entry: Move PTI_USER_* to arch/x86/include/asm/processor-flags.h Lai Jiangshan
2021-11-10 11:56 ` [PATCH V5 09/50] x86: Remove unused kernel_to_user_p4dp() and user_to_kernel_p4dp() Lai Jiangshan
2021-11-10 11:56 ` [PATCH V5 10/50] x86: Replace PTI_PGTABLE_SWITCH_BIT with PTI_USER_PGTABLE_BIT Lai Jiangshan
2021-11-10 11:56 ` [PATCH V5 11/50] x86: Mark __native_read_cr3() & native_write_cr3() as __always_inline Lai Jiangshan
2021-11-10 11:56 ` [PATCH V5 12/50] x86/traps: Move the declaration of native_irq_return_iret into proto.h Lai Jiangshan
2021-11-10 11:56 ` [PATCH V5 13/50] x86/entry: Add arch/x86/entry/entry64.c for C entry code Lai Jiangshan
2021-11-10 11:57 ` [PATCH V5 14/50] x86/entry: Expose the address of .Lgs_change to entry64.c Lai Jiangshan
2021-11-18 20:13 ` Peter Zijlstra
2021-11-10 11:57 ` [PATCH V5 15/50] x86/entry: Add C verion of SWITCH_TO_KERNEL_CR3 as switch_to_kernel_cr3() Lai Jiangshan
2021-11-10 11:57 ` [PATCH V5 16/50] x86/traps: Add fence_swapgs_{user,kernel}_entry() Lai Jiangshan
2021-11-10 11:57 ` [PATCH V5 17/50] x86/entry: Add C user_entry_swapgs_and_fence() Lai Jiangshan
2021-11-10 11:57 ` [PATCH V5 18/50] x86/traps: Move pt_regs only in fixup_bad_iret() Lai Jiangshan
2021-11-10 11:57 ` [PATCH V5 19/50] x86/entry: Switch the stack after error_entry() returns Lai Jiangshan
2021-11-10 11:57 ` [PATCH V5 20/50] x86/entry: move PUSH_AND_CLEAR_REGS out of error_entry Lai Jiangshan
2021-11-10 11:57 ` [PATCH V5 21/50] x86/entry: Move cld to the start of idtentry Lai Jiangshan
2021-11-10 11:57 ` [PATCH V5 22/50] x86/entry: Don't call error_entry for XENPV Lai Jiangshan
2021-11-10 11:57 ` [PATCH V5 23/50] x86/entry: Convert SWAPGS to swapgs in error_entry() Lai Jiangshan
2021-11-10 11:57 ` [PATCH V5 24/50] x86/entry: Implement the whole error_entry() as C code Lai Jiangshan
2021-11-10 11:57 ` [PATCH V5 25/50] x86/entry: Use idtentry macro for entry_INT80_compat Lai Jiangshan
2021-11-10 11:57 ` [PATCH V5 26/50] x86/entry: Convert SWAPGS to swapgs in entry_SYSENTER_compat() Lai Jiangshan
2021-11-10 11:57 ` [PATCH V5 27/50] x86: Remove the definition of SWAPGS Lai Jiangshan
2021-11-10 11:57 ` [PATCH V5 28/50] x86/entry: Make paranoid_exit() callable Lai Jiangshan
2021-11-10 11:57 ` [PATCH V5 29/50] x86/entry: Call paranoid_exit() in asm_exc_nmi() Lai Jiangshan
2021-11-10 11:57 ` [PATCH V5 30/50] x86/entry: move PUSH_AND_CLEAR_REGS out of paranoid_entry Lai Jiangshan
2021-11-10 11:57 ` [PATCH V5 31/50] x86/entry: Add the C version ist_switch_to_kernel_cr3() Lai Jiangshan
2021-11-10 11:57 ` [PATCH V5 32/50] x86/entry: Skip CR3 write when the saved CR3 is kernel CR3 in RESTORE_CR3 Lai Jiangshan
2021-11-10 11:57 ` [PATCH V5 33/50] x86/entry: Add the C version ist_restore_cr3() Lai Jiangshan
2021-11-10 11:57 ` [PATCH V5 34/50] x86/entry: Add the C version get_percpu_base() Lai Jiangshan
2021-11-10 11:57 ` [PATCH V5 35/50] x86/entry: Add the C version ist_switch_to_kernel_gsbase() Lai Jiangshan
2021-11-10 11:57 ` [PATCH V5 36/50] x86/entry: Implement the C version ist_paranoid_entry() Lai Jiangshan
2021-11-10 11:57 ` [PATCH V5 37/50] x86/entry: Implement the C version ist_paranoid_exit() Lai Jiangshan
2021-11-10 11:57 ` [PATCH V5 38/50] x86/entry: Add a C macro to define the function body for IST in .entry.text Lai Jiangshan
2021-11-10 11:57 ` [PATCH V5 39/50] x86/debug, mce: Use C entry code Lai Jiangshan
2021-11-10 11:57 ` [PATCH V5 40/50] x86/idtentry.h: Move the definitions *IDTENTRY_{MCE|DEBUG}* up Lai Jiangshan
2021-11-10 11:57 ` [PATCH V5 41/50] x86/nmi: Use DEFINE_IDTENTRY_NMI for nmi Lai Jiangshan
2021-11-10 11:57 ` [PATCH V5 42/50] x86/nmi: Use C entry code Lai Jiangshan
2021-11-10 11:57 ` [PATCH V5 43/50] x86/entry: Add a C macro to define the function body for IST in .entry.text with an error code Lai Jiangshan
2021-11-10 11:57 ` [PATCH V5 44/50] x86/doublefault: Use C entry code Lai Jiangshan
2021-11-10 11:57 ` [PATCH V5 45/50] x86/sev: Add and use ist_vc_switch_off_ist() Lai Jiangshan
2021-11-10 11:57 ` [PATCH V5 46/50] x86/sev: Use C entry code Lai Jiangshan
2021-11-18 9:31 ` Liam Merwick
2021-11-18 11:04 ` Lai Jiangshan
2021-11-10 11:57 ` [PATCH V5 47/50] x86/entry: Remove ASM function paranoid_entry() and paranoid_exit() Lai Jiangshan
2021-11-10 11:57 ` [PATCH V5 48/50] x86/entry: Remove the unused ASM macros Lai Jiangshan
2021-11-10 11:57 ` [PATCH V5 49/50] x86/entry: Remove save_ret from PUSH_AND_CLEAR_REGS Lai Jiangshan
2021-11-10 11:57 ` [PATCH V5 50/50] x86/syscall/64: Move the checking for sysret to C code Lai Jiangshan
2021-11-18 8:54 ` [PATCH V5 00/50] x86/entry/64: Convert a bunch of ASM entry code into " Lai Jiangshan
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