From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Garnier Subject: [PATCH v6 02/27] x86: Use symbol name in jump table for PIE support Date: Thu, 31 Jan 2019 11:24:09 -0800 Message-Id: <20190131192533.34130-3-thgarnie@chromium.org> In-Reply-To: <20190131192533.34130-1-thgarnie@chromium.org> References: <20190131192533.34130-1-thgarnie@chromium.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit To: kernel-hardening@lists.openwall.com Cc: kristen@linux.intel.com, Thomas Garnier , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , x86@kernel.org, "Peter Zijlstra (Intel)" , Ard Biesheuvel , Thomas Garnier , Nadav Amit , Masahiro Yamada , linux-kernel@vger.kernel.org List-ID: Replace the %c constraint with %P. The %c is incompatible with PIE because it implies an immediate value whereas %P reference a symbol. Change the _ASM_PTR reference to .long for expected relocation size and add a long padding to ensure entry alignment. Position Independent Executable (PIE) support will allow to extend the KASLR randomization range below 0xffffffff80000000. Signed-off-by: Thomas Garnier --- arch/x86/include/asm/jump_label.h | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/arch/x86/include/asm/jump_label.h b/arch/x86/include/asm/jump_label.h index 65191ce8e1cf..e47fad8ee632 100644 --- a/arch/x86/include/asm/jump_label.h +++ b/arch/x86/include/asm/jump_label.h @@ -25,9 +25,9 @@ static __always_inline bool arch_static_branch(struct static_key *key, bool bran ".pushsection __jump_table, \"aw\" \n\t" _ASM_ALIGN "\n\t" ".long 1b - ., %l[l_yes] - . \n\t" - _ASM_PTR "%c0 + %c1 - .\n\t" + _ASM_PTR "%P0 - .\n\t" ".popsection \n\t" - : : "i" (key), "i" (branch) : : l_yes); + : : "X" (&((char *)key)[branch]) : : l_yes); return false; l_yes: @@ -42,9 +42,9 @@ static __always_inline bool arch_static_branch_jump(struct static_key *key, bool ".pushsection __jump_table, \"aw\" \n\t" _ASM_ALIGN "\n\t" ".long 1b - ., %l[l_yes] - . \n\t" - _ASM_PTR "%c0 + %c1 - .\n\t" + _ASM_PTR "%P0 - .\n\t" ".popsection \n\t" - : : "i" (key), "i" (branch) : : l_yes); + : : "X" (&((char *)key)[branch]) : : l_yes); return false; l_yes: -- 2.20.1.495.gaa96b0ce6b-goog