diff options
Diffstat (limited to 'common/recipes-kernel/linux/linux-yocto-4.9.21/0080-x86-retpoline-Add-LFENCE-to-the-retpoline-RSB-fillin.patch')
| -rw-r--r-- | common/recipes-kernel/linux/linux-yocto-4.9.21/0080-x86-retpoline-Add-LFENCE-to-the-retpoline-RSB-fillin.patch | 94 |
1 files changed, 0 insertions, 94 deletions
diff --git a/common/recipes-kernel/linux/linux-yocto-4.9.21/0080-x86-retpoline-Add-LFENCE-to-the-retpoline-RSB-fillin.patch b/common/recipes-kernel/linux/linux-yocto-4.9.21/0080-x86-retpoline-Add-LFENCE-to-the-retpoline-RSB-fillin.patch deleted file mode 100644 index acb54587..00000000 --- a/common/recipes-kernel/linux/linux-yocto-4.9.21/0080-x86-retpoline-Add-LFENCE-to-the-retpoline-RSB-fillin.patch +++ /dev/null @@ -1,94 +0,0 @@ -From b72091ebb94e5cb7808c813989e6b5aefa464751 Mon Sep 17 00:00:00 2001 -From: Tom Lendacky <thomas.lendacky@amd.com> -Date: Sat, 13 Jan 2018 17:27:30 -0600 -Subject: [PATCH 080/103] x86/retpoline: Add LFENCE to the retpoline/RSB - filling RSB macros - -commit 28d437d550e1e39f805d99f9f8ac399c778827b7 upstream. - -The PAUSE instruction is currently used in the retpoline and RSB filling -macros as a speculation trap. The use of PAUSE was originally suggested -because it showed a very, very small difference in the amount of -cycles/time used to execute the retpoline as compared to LFENCE. On AMD, -the PAUSE instruction is not a serializing instruction, so the pause/jmp -loop will use excess power as it is speculated over waiting for return -to mispredict to the correct target. - -The RSB filling macro is applicable to AMD, and, if software is unable to -verify that LFENCE is serializing on AMD (possible when running under a -hypervisor), the generic retpoline support will be used and, so, is also -applicable to AMD. Keep the current usage of PAUSE for Intel, but add an -LFENCE instruction to the speculation trap for AMD. - -The same sequence has been adopted by GCC for the GCC generated retpolines. - -Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com> -Signed-off-by: Thomas Gleixner <tglx@linutronix.de> -Reviewed-by: Borislav Petkov <bp@alien8.de> -Acked-by: David Woodhouse <dwmw@amazon.co.uk> -Acked-by: Arjan van de Ven <arjan@linux.intel.com> -Cc: Rik van Riel <riel@redhat.com> -Cc: Andi Kleen <ak@linux.intel.com> -Cc: Paul Turner <pjt@google.com> -Cc: Peter Zijlstra <peterz@infradead.org> -Cc: Tim Chen <tim.c.chen@linux.intel.com> -Cc: Jiri Kosina <jikos@kernel.org> -Cc: Dave Hansen <dave.hansen@intel.com> -Cc: Andy Lutomirski <luto@kernel.org> -Cc: Josh Poimboeuf <jpoimboe@redhat.com> -Cc: Dan Williams <dan.j.williams@intel.com> -Cc: Linus Torvalds <torvalds@linux-foundation.org> -Cc: Greg Kroah-Hartman <gregkh@linux-foundation.org> -Cc: Kees Cook <keescook@google.com> -Link: https://lkml.kernel.org/r/20180113232730.31060.36287.stgit@tlendack-t1.amdoffice.net -Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> ---- - arch/x86/include/asm/nospec-branch.h | 6 +++++- - 1 file changed, 5 insertions(+), 1 deletion(-) - -diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h -index 402a11c..7b45d84 100644 ---- a/arch/x86/include/asm/nospec-branch.h -+++ b/arch/x86/include/asm/nospec-branch.h -@@ -11,7 +11,7 @@ - * Fill the CPU return stack buffer. - * - * Each entry in the RSB, if used for a speculative 'ret', contains an -- * infinite 'pause; jmp' loop to capture speculative execution. -+ * infinite 'pause; lfence; jmp' loop to capture speculative execution. - * - * This is required in various cases for retpoline and IBRS-based - * mitigations for the Spectre variant 2 vulnerability. Sometimes to -@@ -38,11 +38,13 @@ - call 772f; \ - 773: /* speculation trap */ \ - pause; \ -+ lfence; \ - jmp 773b; \ - 772: \ - call 774f; \ - 775: /* speculation trap */ \ - pause; \ -+ lfence; \ - jmp 775b; \ - 774: \ - dec reg; \ -@@ -73,6 +75,7 @@ - call .Ldo_rop_\@ - .Lspec_trap_\@: - pause -+ lfence - jmp .Lspec_trap_\@ - .Ldo_rop_\@: - mov \reg, (%_ASM_SP) -@@ -165,6 +168,7 @@ - " .align 16\n" \ - "901: call 903f;\n" \ - "902: pause;\n" \ -+ " lfence;\n" \ - " jmp 902b;\n" \ - " .align 16\n" \ - "903: addl $4, %%esp;\n" \ --- -2.7.4 - |