diff options
Diffstat (limited to 'debian/patches/bugfix/x86/retbleed/0035-x86-speculation-Fix-RSB-filling-with-CONFIG_RETPOLIN.patch')
| -rw-r--r-- | debian/patches/bugfix/x86/retbleed/0035-x86-speculation-Fix-RSB-filling-with-CONFIG_RETPOLIN.patch | 77 |
1 files changed, 77 insertions, 0 deletions
diff --git a/debian/patches/bugfix/x86/retbleed/0035-x86-speculation-Fix-RSB-filling-with-CONFIG_RETPOLIN.patch b/debian/patches/bugfix/x86/retbleed/0035-x86-speculation-Fix-RSB-filling-with-CONFIG_RETPOLIN.patch new file mode 100644 index 000000000..a81fefcec --- /dev/null +++ b/debian/patches/bugfix/x86/retbleed/0035-x86-speculation-Fix-RSB-filling-with-CONFIG_RETPOLIN.patch @@ -0,0 +1,77 @@ +From: Josh Poimboeuf <jpoimboe@kernel.org> +Date: Tue, 14 Jun 2022 23:16:05 +0200 +Subject: x86/speculation: Fix RSB filling with CONFIG_RETPOLINE=n +Origin: https://git.kernel.org/linus/b2620facef4889fefcbf2e87284f34dcd4189bce + +If a kernel is built with CONFIG_RETPOLINE=n, but the user still wants +to mitigate Spectre v2 using IBRS or eIBRS, the RSB filling will be +silently disabled. + +There's nothing retpoline-specific about RSB buffer filling. Remove the +CONFIG_RETPOLINE guards around it. + +Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> +Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> +Signed-off-by: Borislav Petkov <bp@suse.de> +--- + arch/x86/entry/entry_32.S | 2 -- + arch/x86/entry/entry_64.S | 2 -- + arch/x86/include/asm/nospec-branch.h | 2 -- + 3 files changed, 6 deletions(-) + +diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S +index 887420844066..e309e7156038 100644 +--- a/arch/x86/entry/entry_32.S ++++ b/arch/x86/entry/entry_32.S +@@ -698,7 +698,6 @@ SYM_CODE_START(__switch_to_asm) + movl %ebx, PER_CPU_VAR(__stack_chk_guard) + #endif + +-#ifdef CONFIG_RETPOLINE + /* + * When switching from a shallower to a deeper call stack + * the RSB may either underflow or use entries populated +@@ -707,7 +706,6 @@ SYM_CODE_START(__switch_to_asm) + * speculative execution to prevent attack. + */ + FILL_RETURN_BUFFER %ebx, RSB_CLEAR_LOOPS, X86_FEATURE_RSB_CTXSW +-#endif + + /* Restore flags or the incoming task to restore AC state. */ + popfl +diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S +index 65e3b8b7cbe5..a4ba162e52c3 100644 +--- a/arch/x86/entry/entry_64.S ++++ b/arch/x86/entry/entry_64.S +@@ -255,7 +255,6 @@ SYM_FUNC_START(__switch_to_asm) + movq %rbx, PER_CPU_VAR(fixed_percpu_data) + stack_canary_offset + #endif + +-#ifdef CONFIG_RETPOLINE + /* + * When switching from a shallower to a deeper call stack + * the RSB may either underflow or use entries populated +@@ -264,7 +263,6 @@ SYM_FUNC_START(__switch_to_asm) + * speculative execution to prevent attack. + */ + FILL_RETURN_BUFFER %r12, RSB_CLEAR_LOOPS, X86_FEATURE_RSB_CTXSW +-#endif + + /* restore callee-saved registers */ + popq %r15 +diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h +index bba42bd78edf..08b03c12e6c2 100644 +--- a/arch/x86/include/asm/nospec-branch.h ++++ b/arch/x86/include/asm/nospec-branch.h +@@ -122,11 +122,9 @@ + * monstrosity above, manually. + */ + .macro FILL_RETURN_BUFFER reg:req nr:req ftr:req +-#ifdef CONFIG_RETPOLINE + ALTERNATIVE "jmp .Lskip_rsb_\@", "", \ftr + __FILL_RETURN_BUFFER(\reg,\nr,%_ASM_SP) + .Lskip_rsb_\@: +-#endif + .endm + + /* |