[PATCH v2 00/27] x86: PIE support and option to extend KASLR randomization

[PATCH v2 00/27] x86: PIE support and option to extend KASLR randomization

[Thomas Garnier]

Changes:
 - patch v2:
   - Adapt patch to work post KPTI and compiler changes
   - Redo all performance testing with latest configs and compilers
   - Simplify mov macro on PIE (MOVABS now)
   - Reduce GOT footprint
 - patch v1:
   - Simplify ftrace implementation.
   - Use gcc mstack-protector-guard-reg=%gs with PIE when possible.
 - rfc v3:
   - Use --emit-relocs instead of -pie to reduce dynamic relocation space on
     mapped memory. It also simplifies the relocation process.
   - Move the start the module section next to the kernel. Remove the need for
     -mcmodel=large on modules. Extends module space from 1 to 2G maximum.
   - Support for XEN PVH as 32-bit relocations can be ignored with
     --emit-relocs.
   - Support for GOT relocations previously done automatically with -pie.
   - Remove need for dynamic PLT in modules.
   - Support dymamic GOT for modules.
 - rfc v2:
   - Add support for global stack cookie while compiler default to fs without
     mcmodel=kernel
   - Change patch 7 to correctly jump out of the identity mapping on kexec load
     preserve.

These patches make the changes necessary to build the kernel as Position
Independent Executable (PIE) on x86_64. A PIE kernel can be relocated below
the top 2G of the virtual address space. It allows to optionally extend the
KASLR randomization range from 1G to 3G.

Thanks a lot to Ard Biesheuvel & Kees Cook on their feedback on compiler
changes, PIE support and KASLR in general. Thanks to Roland McGrath on his
feedback for using -pie versus --emit-relocs and details on compiler code
generation.

The patches:
 - 1-3, 5-13, 18-19: Change in assembly code to be PIE compliant.
 - 4: Add a new _ASM_GET_PTR macro to fetch a symbol address generically.
 - 14: Adapt percpu design to work correctly when PIE is enabled.
 - 15: Provide an option to default visibility to hidden except for key symbols.
       It removes errors between compilation units.
 - 16: Add PROVIDE_HIDDEN replacement on the linker script for weak symbols to
       reduce GOT footprint.
 - 17: Adapt relocation tool to handle PIE binary correctly.
 - 20: Add support for global cookie.
 - 21: Support ftrace with PIE (used on Ubuntu config).
 - 22: Add option to move the module section just after the kernel.
 - 23: Adapt module loading to support PIE with dynamic GOT.
 - 24: Make the GOT read-only.
 - 25: Add the CONFIG_X86_PIE option (off by default).
 - 26: Adapt relocation tool to generate a 64-bit relocation table.
 - 27: Add the CONFIG_RANDOMIZE_BASE_LARGE option to increase relocation range
       from 1G to 3G (off by default).

Performance/Size impact:

Size of vmlinux (Default configuration):
 File size:
 - PIE disabled: +0.18%
 - PIE enabled: -1.977% (less relocations)
 .text section:
 - PIE disabled: same
 - PIE enabled: same

Size of vmlinux (Ubuntu configuration):
 File size:
 - PIE disabled: +0.21%
 - PIE enabled: +10%
 .text section:
 - PIE disabled: same
 - PIE enabled: +0.001%

The size increase is mainly due to not having access to the 32-bit signed
relocation that can be used with mcmodel=kernel. A small part is due to reduced
optimization for PIE code. This bug [1] was opened with gcc to provide a better
code generation for kernel PIE.

Hackbench (50% and 1600% on thread/process for pipe/sockets):
 - PIE disabled: no significant change (avg -/+ 0.5% on latest test).
 - PIE enabled: between -1% to +1% in average (default and Ubuntu config).

Kernbench (average of 10 Half and Optimal runs):
 Elapsed Time:
 - PIE disabled: no significant change (avg -0.5%)
 - PIE enabled: average -0.5% to +0.5%
 System Time:
 - PIE disabled: no significant change (avg -0.1%)
 - PIE enabled: average -0.4% to +0.4%.

[1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82303

diffstat:
 Documentation/x86/x86_64/mm.txt              |    3 
 arch/x86/Kconfig                             |   45 ++++++
 arch/x86/Makefile                            |   58 ++++++++
 arch/x86/boot/boot.h                         |    2 
 arch/x86/boot/compressed/Makefile            |    5 
 arch/x86/boot/compressed/misc.c              |   10 +
 arch/x86/crypto/aes-x86_64-asm_64.S          |   45 ++++--
 arch/x86/crypto/aesni-intel_asm.S            |    8 -
 arch/x86/crypto/aesni-intel_avx-x86_64.S     |    6 
 arch/x86/crypto/camellia-aesni-avx-asm_64.S  |   42 +++---
 arch/x86/crypto/camellia-aesni-avx2-asm_64.S |   44 +++---
 arch/x86/crypto/camellia-x86_64-asm_64.S     |    8 -
 arch/x86/crypto/cast5-avx-x86_64-asm_64.S    |   50 ++++---
 arch/x86/crypto/cast6-avx-x86_64-asm_64.S    |   44 +++---
 arch/x86/crypto/des3_ede-asm_64.S            |   96 +++++++++-----
 arch/x86/crypto/ghash-clmulni-intel_asm.S    |    4 
 arch/x86/crypto/glue_helper-asm-avx.S        |    4 
 arch/x86/crypto/glue_helper-asm-avx2.S       |    6 
 arch/x86/crypto/sha256-avx2-asm.S            |   23 ++-
 arch/x86/entry/calling.h                     |    2 
 arch/x86/entry/entry_32.S                    |    3 
 arch/x86/entry/entry_64.S                    |   23 ++-
 arch/x86/include/asm/asm.h                   |    1 
 arch/x86/include/asm/bug.h                   |    2 
 arch/x86/include/asm/ftrace.h                |    6 
 arch/x86/include/asm/jump_label.h            |    8 -
 arch/x86/include/asm/kvm_host.h              |    6 
 arch/x86/include/asm/module.h                |   11 +
 arch/x86/include/asm/page_64_types.h         |    9 +
 arch/x86/include/asm/paravirt_types.h        |   12 +
 arch/x86/include/asm/percpu.h                |   25 ++-
 arch/x86/include/asm/pgtable_64_types.h      |    6 
 arch/x86/include/asm/pm-trace.h              |    2 
 arch/x86/include/asm/processor.h             |   12 +
 arch/x86/include/asm/sections.h              |    8 +
 arch/x86/include/asm/setup.h                 |    2 
 arch/x86/include/asm/stackprotector.h        |   19 ++
 arch/x86/kernel/Makefile                     |    6 
 arch/x86/kernel/acpi/wakeup_64.S             |   31 ++--
 arch/x86/kernel/asm-offsets.c                |    3 
 arch/x86/kernel/asm-offsets_32.c             |    3 
 arch/x86/kernel/asm-offsets_64.c             |    3 
 arch/x86/kernel/cpu/common.c                 |    7 -
 arch/x86/kernel/cpu/microcode/core.c         |    4 
 arch/x86/kernel/ftrace.c                     |   42 +++++-
 arch/x86/kernel/head64.c                     |   23 ++-
 arch/x86/kernel/head_32.S                    |    3 
 arch/x86/kernel/head_64.S                    |   41 +++++-
 arch/x86/kernel/kvm.c                        |    6 
 arch/x86/kernel/module.c                     |  181 ++++++++++++++++++++++++++-
 arch/x86/kernel/module.lds                   |    3 
 arch/x86/kernel/process.c                    |    5 
 arch/x86/kernel/relocate_kernel_64.S         |   16 +-
 arch/x86/kernel/setup_percpu.c               |    2 
 arch/x86/kernel/vmlinux.lds.S                |   13 +
 arch/x86/kvm/svm.c                           |    4 
 arch/x86/lib/cmpxchg16b_emu.S                |    8 -
 arch/x86/mm/dump_pagetables.c                |    3 
 arch/x86/power/hibernate_asm_64.S            |    4 
 arch/x86/tools/relocs.c                      |  169 +++++++++++++++++++++++--
 arch/x86/tools/relocs.h                      |    4 
 arch/x86/tools/relocs_common.c               |   15 +-
 arch/x86/xen/xen-asm.S                       |   12 -
 arch/x86/xen/xen-head.S                      |   11 -
 arch/x86/xen/xen-pvh.S                       |   13 +
 drivers/base/firmware_class.c                |    4 
 include/asm-generic/sections.h               |    6 
 include/asm-generic/vmlinux.lds.h            |   12 +
 include/linux/compiler.h                     |    7 +
 init/Kconfig                                 |   16 ++
 kernel/kallsyms.c                            |   16 +-
 kernel/trace/trace.h                         |    4 
 lib/dynamic_debug.c                          |    4 
 scripts/link-vmlinux.sh                      |   14 ++
 74 files changed, 1063 insertions(+), 315 deletions(-)

[PATCH v2 01/27] x86/crypto: Adapt assembly for PIE support

[Thomas Garnier]

Change the assembly code to use only relative references of symbols for the
kernel to be PIE compatible.

Position Independent Executable (PIE) support will allow to extended the
KASLR randomization range below the -2G memory limit.

Signed-off-by: Thomas Garnier <thgarnie@google.com>
---
 arch/x86/crypto/aes-x86_64-asm_64.S          | 45 +++++----
 arch/x86/crypto/aesni-intel_asm.S            |  8 +-
 arch/x86/crypto/aesni-intel_avx-x86_64.S     |  6 +-
 arch/x86/crypto/camellia-aesni-avx-asm_64.S  | 42 ++++-----
 arch/x86/crypto/camellia-aesni-avx2-asm_64.S | 44 ++++-----
 arch/x86/crypto/camellia-x86_64-asm_64.S     |  8 +-
 arch/x86/crypto/cast5-avx-x86_64-asm_64.S    | 50 +++++-----
 arch/x86/crypto/cast6-avx-x86_64-asm_64.S    | 44 +++++----
 arch/x86/crypto/des3_ede-asm_64.S            | 96 +++++++++++++-------
 arch/x86/crypto/ghash-clmulni-intel_asm.S    |  4 +-
 arch/x86/crypto/glue_helper-asm-avx.S        |  4 +-
 arch/x86/crypto/glue_helper-asm-avx2.S       |  6 +-
 arch/x86/crypto/sha256-avx2-asm.S            | 23 +++--
 13 files changed, 221 insertions(+), 159 deletions(-)

diff --git a/arch/x86/crypto/aes-x86_64-asm_64.S b/arch/x86/crypto/aes-x86_64-asm_64.S
index 8739cf7795de..86fa068e5e81 100644
--- a/arch/x86/crypto/aes-x86_64-asm_64.S
+++ b/arch/x86/crypto/aes-x86_64-asm_64.S
@@ -48,8 +48,12 @@
 #define R10	%r10
 #define R11	%r11
 
+/* Hold global for PIE suport */
+#define RBASE	%r12
+
 #define prologue(FUNC,KEY,B128,B192,r1,r2,r5,r6,r7,r8,r9,r10,r11) \
 	ENTRY(FUNC);			\
+	pushq	RBASE;			\
 	movq	r1,r2;			\
 	leaq	KEY+48(r8),r9;		\
 	movq	r10,r11;		\
@@ -74,54 +78,63 @@
 	movl	r6 ## E,4(r9);		\
 	movl	r7 ## E,8(r9);		\
 	movl	r8 ## E,12(r9);		\
+	popq	RBASE;			\
 	ret;				\
 	ENDPROC(FUNC);
 
+#define round_mov(tab_off, reg_i, reg_o) \
+	leaq	tab_off(%rip), RBASE; \
+	movl	(RBASE,reg_i,4), reg_o;
+
+#define round_xor(tab_off, reg_i, reg_o) \
+	leaq	tab_off(%rip), RBASE; \
+	xorl	(RBASE,reg_i,4), reg_o;
+
 #define round(TAB,OFFSET,r1,r2,r3,r4,r5,r6,r7,r8,ra,rb,rc,rd) \
 	movzbl	r2 ## H,r5 ## E;	\
 	movzbl	r2 ## L,r6 ## E;	\
-	movl	TAB+1024(,r5,4),r5 ## E;\
+	round_mov(TAB+1024, r5, r5 ## E)\
 	movw	r4 ## X,r2 ## X;	\
-	movl	TAB(,r6,4),r6 ## E;	\
+	round_mov(TAB, r6, r6 ## E)	\
 	roll	$16,r2 ## E;		\
 	shrl	$16,r4 ## E;		\
 	movzbl	r4 ## L,r7 ## E;	\
 	movzbl	r4 ## H,r4 ## E;	\
 	xorl	OFFSET(r8),ra ## E;	\
 	xorl	OFFSET+4(r8),rb ## E;	\
-	xorl	TAB+3072(,r4,4),r5 ## E;\
-	xorl	TAB+2048(,r7,4),r6 ## E;\
+	round_xor(TAB+3072, r4, r5 ## E)\
+	round_xor(TAB+2048, r7, r6 ## E)\
 	movzbl	r1 ## L,r7 ## E;	\
 	movzbl	r1 ## H,r4 ## E;	\
-	movl	TAB+1024(,r4,4),r4 ## E;\
+	round_mov(TAB+1024, r4, r4 ## E)\
 	movw	r3 ## X,r1 ## X;	\
 	roll	$16,r1 ## E;		\
 	shrl	$16,r3 ## E;		\
-	xorl	TAB(,r7,4),r5 ## E;	\
+	round_xor(TAB, r7, r5 ## E)	\
 	movzbl	r3 ## L,r7 ## E;	\
 	movzbl	r3 ## H,r3 ## E;	\
-	xorl	TAB+3072(,r3,4),r4 ## E;\
-	xorl	TAB+2048(,r7,4),r5 ## E;\
+	round_xor(TAB+3072, r3, r4 ## E)\
+	round_xor(TAB+2048, r7, r5 ## E)\
 	movzbl	r1 ## L,r7 ## E;	\
 	movzbl	r1 ## H,r3 ## E;	\
 	shrl	$16,r1 ## E;		\
-	xorl	TAB+3072(,r3,4),r6 ## E;\
-	movl	TAB+2048(,r7,4),r3 ## E;\
+	round_xor(TAB+3072, r3, r6 ## E)\
+	round_mov(TAB+2048, r7, r3 ## E)\
 	movzbl	r1 ## L,r7 ## E;	\
 	movzbl	r1 ## H,r1 ## E;	\
-	xorl	TAB+1024(,r1,4),r6 ## E;\
-	xorl	TAB(,r7,4),r3 ## E;	\
+	round_xor(TAB+1024, r1, r6 ## E)\
+	round_xor(TAB, r7, r3 ## E)	\
 	movzbl	r2 ## H,r1 ## E;	\
 	movzbl	r2 ## L,r7 ## E;	\
 	shrl	$16,r2 ## E;		\
-	xorl	TAB+3072(,r1,4),r3 ## E;\
-	xorl	TAB+2048(,r7,4),r4 ## E;\
+	round_xor(TAB+3072, r1, r3 ## E)\
+	round_xor(TAB+2048, r7, r4 ## E)\
 	movzbl	r2 ## H,r1 ## E;	\
 	movzbl	r2 ## L,r2 ## E;	\
 	xorl	OFFSET+8(r8),rc ## E;	\
 	xorl	OFFSET+12(r8),rd ## E;	\
-	xorl	TAB+1024(,r1,4),r3 ## E;\
-	xorl	TAB(,r2,4),r4 ## E;
+	round_xor(TAB+1024, r1, r3 ## E)\
+	round_xor(TAB, r2, r4 ## E)
 
 #define move_regs(r1,r2,r3,r4) \
 	movl	r3 ## E,r1 ## E;	\
diff --git a/arch/x86/crypto/aesni-intel_asm.S b/arch/x86/crypto/aesni-intel_asm.S
index e762ef417562..4df029aa5fc1 100644
--- a/arch/x86/crypto/aesni-intel_asm.S
+++ b/arch/x86/crypto/aesni-intel_asm.S
@@ -2610,7 +2610,7 @@ ENDPROC(aesni_cbc_dec)
  */
 .align 4
 _aesni_inc_init:
-	movaps .Lbswap_mask, BSWAP_MASK
+	movaps .Lbswap_mask(%rip), BSWAP_MASK
 	movaps IV, CTR
 	PSHUFB_XMM BSWAP_MASK CTR
 	mov $1, TCTR_LOW
@@ -2738,12 +2738,12 @@ ENTRY(aesni_xts_crypt8)
 	cmpb $0, %cl
 	movl $0, %ecx
 	movl $240, %r10d
-	leaq _aesni_enc4, %r11
-	leaq _aesni_dec4, %rax
+	leaq _aesni_enc4(%rip), %r11
+	leaq _aesni_dec4(%rip), %rax
 	cmovel %r10d, %ecx
 	cmoveq %rax, %r11
 
-	movdqa .Lgf128mul_x_ble_mask, GF128MUL_MASK
+	movdqa .Lgf128mul_x_ble_mask(%rip), GF128MUL_MASK
 	movups (IVP), IV
 
 	mov 480(KEYP), KLEN
diff --git a/arch/x86/crypto/aesni-intel_avx-x86_64.S b/arch/x86/crypto/aesni-intel_avx-x86_64.S
index faecb1518bf8..488605b19fe8 100644
--- a/arch/x86/crypto/aesni-intel_avx-x86_64.S
+++ b/arch/x86/crypto/aesni-intel_avx-x86_64.S
@@ -454,7 +454,8 @@ _get_AAD_rest0\@:
 	vpshufb and an array of shuffle masks */
 	movq    %r12, %r11
 	salq    $4, %r11
-	movdqu  aad_shift_arr(%r11), \T1
+	leaq	aad_shift_arr(%rip), %rax
+	movdqu  (%rax,%r11,), \T1
 	vpshufb \T1, reg_i, reg_i
 _get_AAD_rest_final\@:
 	vpshufb SHUF_MASK(%rip), reg_i, reg_i
@@ -1761,7 +1762,8 @@ _get_AAD_rest0\@:
 	vpshufb and an array of shuffle masks */
 	movq    %r12, %r11
 	salq    $4, %r11
-	movdqu  aad_shift_arr(%r11), \T1
+	leaq	aad_shift_arr(%rip), %rax
+	movdqu  (%rax,%r11,), \T1
 	vpshufb \T1, reg_i, reg_i
 _get_AAD_rest_final\@:
 	vpshufb SHUF_MASK(%rip), reg_i, reg_i
diff --git a/arch/x86/crypto/camellia-aesni-avx-asm_64.S b/arch/x86/crypto/camellia-aesni-avx-asm_64.S
index a14af6eb09cb..f94ec9a5552b 100644
--- a/arch/x86/crypto/camellia-aesni-avx-asm_64.S
+++ b/arch/x86/crypto/camellia-aesni-avx-asm_64.S
@@ -53,10 +53,10 @@
 	/* \
 	 * S-function with AES subbytes \
 	 */ \
-	vmovdqa .Linv_shift_row, t4; \
-	vbroadcastss .L0f0f0f0f, t7; \
-	vmovdqa .Lpre_tf_lo_s1, t0; \
-	vmovdqa .Lpre_tf_hi_s1, t1; \
+	vmovdqa .Linv_shift_row(%rip), t4; \
+	vbroadcastss .L0f0f0f0f(%rip), t7; \
+	vmovdqa .Lpre_tf_lo_s1(%rip), t0; \
+	vmovdqa .Lpre_tf_hi_s1(%rip), t1; \
 	\
 	/* AES inverse shift rows */ \
 	vpshufb t4, x0, x0; \
@@ -69,8 +69,8 @@
 	vpshufb t4, x6, x6; \
 	\
 	/* prefilter sboxes 1, 2 and 3 */ \
-	vmovdqa .Lpre_tf_lo_s4, t2; \
-	vmovdqa .Lpre_tf_hi_s4, t3; \
+	vmovdqa .Lpre_tf_lo_s4(%rip), t2; \
+	vmovdqa .Lpre_tf_hi_s4(%rip), t3; \
 	filter_8bit(x0, t0, t1, t7, t6); \
 	filter_8bit(x7, t0, t1, t7, t6); \
 	filter_8bit(x1, t0, t1, t7, t6); \
@@ -84,8 +84,8 @@
 	filter_8bit(x6, t2, t3, t7, t6); \
 	\
 	/* AES subbytes + AES shift rows */ \
-	vmovdqa .Lpost_tf_lo_s1, t0; \
-	vmovdqa .Lpost_tf_hi_s1, t1; \
+	vmovdqa .Lpost_tf_lo_s1(%rip), t0; \
+	vmovdqa .Lpost_tf_hi_s1(%rip), t1; \
 	vaesenclast t4, x0, x0; \
 	vaesenclast t4, x7, x7; \
 	vaesenclast t4, x1, x1; \
@@ -96,16 +96,16 @@
 	vaesenclast t4, x6, x6; \
 	\
 	/* postfilter sboxes 1 and 4 */ \
-	vmovdqa .Lpost_tf_lo_s3, t2; \
-	vmovdqa .Lpost_tf_hi_s3, t3; \
+	vmovdqa .Lpost_tf_lo_s3(%rip), t2; \
+	vmovdqa .Lpost_tf_hi_s3(%rip), t3; \
 	filter_8bit(x0, t0, t1, t7, t6); \
 	filter_8bit(x7, t0, t1, t7, t6); \
 	filter_8bit(x3, t0, t1, t7, t6); \
 	filter_8bit(x6, t0, t1, t7, t6); \
 	\
 	/* postfilter sbox 3 */ \
-	vmovdqa .Lpost_tf_lo_s2, t4; \
-	vmovdqa .Lpost_tf_hi_s2, t5; \
+	vmovdqa .Lpost_tf_lo_s2(%rip), t4; \
+	vmovdqa .Lpost_tf_hi_s2(%rip), t5; \
 	filter_8bit(x2, t2, t3, t7, t6); \
 	filter_8bit(x5, t2, t3, t7, t6); \
 	\
@@ -444,7 +444,7 @@ ENDPROC(roundsm16_x4_x5_x6_x7_x0_x1_x2_x3_y4_y5_y6_y7_y0_y1_y2_y3_ab)
 	transpose_4x4(c0, c1, c2, c3, a0, a1); \
 	transpose_4x4(d0, d1, d2, d3, a0, a1); \
 	\
-	vmovdqu .Lshufb_16x16b, a0; \
+	vmovdqu .Lshufb_16x16b(%rip), a0; \
 	vmovdqu st1, a1; \
 	vpshufb a0, a2, a2; \
 	vpshufb a0, a3, a3; \
@@ -483,7 +483,7 @@ ENDPROC(roundsm16_x4_x5_x6_x7_x0_x1_x2_x3_y4_y5_y6_y7_y0_y1_y2_y3_ab)
 #define inpack16_pre(x0, x1, x2, x3, x4, x5, x6, x7, y0, y1, y2, y3, y4, y5, \
 		     y6, y7, rio, key) \
 	vmovq key, x0; \
-	vpshufb .Lpack_bswap, x0, x0; \
+	vpshufb .Lpack_bswap(%rip), x0, x0; \
 	\
 	vpxor 0 * 16(rio), x0, y7; \
 	vpxor 1 * 16(rio), x0, y6; \
@@ -534,7 +534,7 @@ ENDPROC(roundsm16_x4_x5_x6_x7_x0_x1_x2_x3_y4_y5_y6_y7_y0_y1_y2_y3_ab)
 	vmovdqu x0, stack_tmp0; \
 	\
 	vmovq key, x0; \
-	vpshufb .Lpack_bswap, x0, x0; \
+	vpshufb .Lpack_bswap(%rip), x0, x0; \
 	\
 	vpxor x0, y7, y7; \
 	vpxor x0, y6, y6; \
@@ -1017,7 +1017,7 @@ ENTRY(camellia_ctr_16way)
 	subq $(16 * 16), %rsp;
 	movq %rsp, %rax;
 
-	vmovdqa .Lbswap128_mask, %xmm14;
+	vmovdqa .Lbswap128_mask(%rip), %xmm14;
 
 	/* load IV and byteswap */
 	vmovdqu (%rcx), %xmm0;
@@ -1066,7 +1066,7 @@ ENTRY(camellia_ctr_16way)
 
 	/* inpack16_pre: */
 	vmovq (key_table)(CTX), %xmm15;
-	vpshufb .Lpack_bswap, %xmm15, %xmm15;
+	vpshufb .Lpack_bswap(%rip), %xmm15, %xmm15;
 	vpxor %xmm0, %xmm15, %xmm0;
 	vpxor %xmm1, %xmm15, %xmm1;
 	vpxor %xmm2, %xmm15, %xmm2;
@@ -1134,7 +1134,7 @@ camellia_xts_crypt_16way:
 	subq $(16 * 16), %rsp;
 	movq %rsp, %rax;
 
-	vmovdqa .Lxts_gf128mul_and_shl1_mask, %xmm14;
+	vmovdqa .Lxts_gf128mul_and_shl1_mask(%rip), %xmm14;
 
 	/* load IV */
 	vmovdqu (%rcx), %xmm0;
@@ -1210,7 +1210,7 @@ camellia_xts_crypt_16way:
 
 	/* inpack16_pre: */
 	vmovq (key_table)(CTX, %r8, 8), %xmm15;
-	vpshufb .Lpack_bswap, %xmm15, %xmm15;
+	vpshufb .Lpack_bswap(%rip), %xmm15, %xmm15;
 	vpxor 0 * 16(%rax), %xmm15, %xmm0;
 	vpxor %xmm1, %xmm15, %xmm1;
 	vpxor %xmm2, %xmm15, %xmm2;
@@ -1265,7 +1265,7 @@ ENTRY(camellia_xts_enc_16way)
 	 */
 	xorl %r8d, %r8d; /* input whitening key, 0 for enc */
 
-	leaq __camellia_enc_blk16, %r9;
+	leaq __camellia_enc_blk16(%rip), %r9;
 
 	jmp camellia_xts_crypt_16way;
 ENDPROC(camellia_xts_enc_16way)
@@ -1283,7 +1283,7 @@ ENTRY(camellia_xts_dec_16way)
 	movl $24, %eax;
 	cmovel %eax, %r8d;  /* input whitening key, last for dec */
 
-	leaq __camellia_dec_blk16, %r9;
+	leaq __camellia_dec_blk16(%rip), %r9;
 
 	jmp camellia_xts_crypt_16way;
 ENDPROC(camellia_xts_dec_16way)
diff --git a/arch/x86/crypto/camellia-aesni-avx2-asm_64.S b/arch/x86/crypto/camellia-aesni-avx2-asm_64.S
index b66bbfa62f50..11bbaa1cd4a7 100644
--- a/arch/x86/crypto/camellia-aesni-avx2-asm_64.S
+++ b/arch/x86/crypto/camellia-aesni-avx2-asm_64.S
@@ -70,12 +70,12 @@
 	/* \
 	 * S-function with AES subbytes \
 	 */ \
-	vbroadcasti128 .Linv_shift_row, t4; \
-	vpbroadcastd .L0f0f0f0f, t7; \
-	vbroadcasti128 .Lpre_tf_lo_s1, t5; \
-	vbroadcasti128 .Lpre_tf_hi_s1, t6; \
-	vbroadcasti128 .Lpre_tf_lo_s4, t2; \
-	vbroadcasti128 .Lpre_tf_hi_s4, t3; \
+	vbroadcasti128 .Linv_shift_row(%rip), t4; \
+	vpbroadcastd .L0f0f0f0f(%rip), t7; \
+	vbroadcasti128 .Lpre_tf_lo_s1(%rip), t5; \
+	vbroadcasti128 .Lpre_tf_hi_s1(%rip), t6; \
+	vbroadcasti128 .Lpre_tf_lo_s4(%rip), t2; \
+	vbroadcasti128 .Lpre_tf_hi_s4(%rip), t3; \
 	\
 	/* AES inverse shift rows */ \
 	vpshufb t4, x0, x0; \
@@ -121,8 +121,8 @@
 	vinserti128 $1, t2##_x, x6, x6; \
 	vextracti128 $1, x1, t3##_x; \
 	vextracti128 $1, x4, t2##_x; \
-	vbroadcasti128 .Lpost_tf_lo_s1, t0; \
-	vbroadcasti128 .Lpost_tf_hi_s1, t1; \
+	vbroadcasti128 .Lpost_tf_lo_s1(%rip), t0; \
+	vbroadcasti128 .Lpost_tf_hi_s1(%rip), t1; \
 	vaesenclast t4##_x, x2##_x, x2##_x; \
 	vaesenclast t4##_x, t6##_x, t6##_x; \
 	vinserti128 $1, t6##_x, x2, x2; \
@@ -137,16 +137,16 @@
 	vinserti128 $1, t2##_x, x4, x4; \
 	\
 	/* postfilter sboxes 1 and 4 */ \
-	vbroadcasti128 .Lpost_tf_lo_s3, t2; \
-	vbroadcasti128 .Lpost_tf_hi_s3, t3; \
+	vbroadcasti128 .Lpost_tf_lo_s3(%rip), t2; \
+	vbroadcasti128 .Lpost_tf_hi_s3(%rip), t3; \
 	filter_8bit(x0, t0, t1, t7, t6); \
 	filter_8bit(x7, t0, t1, t7, t6); \
 	filter_8bit(x3, t0, t1, t7, t6); \
 	filter_8bit(x6, t0, t1, t7, t6); \
 	\
 	/* postfilter sbox 3 */ \
-	vbroadcasti128 .Lpost_tf_lo_s2, t4; \
-	vbroadcasti128 .Lpost_tf_hi_s2, t5; \
+	vbroadcasti128 .Lpost_tf_lo_s2(%rip), t4; \
+	vbroadcasti128 .Lpost_tf_hi_s2(%rip), t5; \
 	filter_8bit(x2, t2, t3, t7, t6); \
 	filter_8bit(x5, t2, t3, t7, t6); \
 	\
@@ -483,7 +483,7 @@ ENDPROC(roundsm32_x4_x5_x6_x7_x0_x1_x2_x3_y4_y5_y6_y7_y0_y1_y2_y3_ab)
 	transpose_4x4(c0, c1, c2, c3, a0, a1); \
 	transpose_4x4(d0, d1, d2, d3, a0, a1); \
 	\
-	vbroadcasti128 .Lshufb_16x16b, a0; \
+	vbroadcasti128 .Lshufb_16x16b(%rip), a0; \
 	vmovdqu st1, a1; \
 	vpshufb a0, a2, a2; \
 	vpshufb a0, a3, a3; \
@@ -522,7 +522,7 @@ ENDPROC(roundsm32_x4_x5_x6_x7_x0_x1_x2_x3_y4_y5_y6_y7_y0_y1_y2_y3_ab)
 #define inpack32_pre(x0, x1, x2, x3, x4, x5, x6, x7, y0, y1, y2, y3, y4, y5, \
 		     y6, y7, rio, key) \
 	vpbroadcastq key, x0; \
-	vpshufb .Lpack_bswap, x0, x0; \
+	vpshufb .Lpack_bswap(%rip), x0, x0; \
 	\
 	vpxor 0 * 32(rio), x0, y7; \
 	vpxor 1 * 32(rio), x0, y6; \
@@ -573,7 +573,7 @@ ENDPROC(roundsm32_x4_x5_x6_x7_x0_x1_x2_x3_y4_y5_y6_y7_y0_y1_y2_y3_ab)
 	vmovdqu x0, stack_tmp0; \
 	\
 	vpbroadcastq key, x0; \
-	vpshufb .Lpack_bswap, x0, x0; \
+	vpshufb .Lpack_bswap(%rip), x0, x0; \
 	\
 	vpxor x0, y7, y7; \
 	vpxor x0, y6, y6; \
@@ -1113,7 +1113,7 @@ ENTRY(camellia_ctr_32way)
 	vmovdqu (%rcx), %xmm0;
 	vmovdqa %xmm0, %xmm1;
 	inc_le128(%xmm0, %xmm15, %xmm14);
-	vbroadcasti128 .Lbswap128_mask, %ymm14;
+	vbroadcasti128 .Lbswap128_mask(%rip), %ymm14;
 	vinserti128 $1, %xmm0, %ymm1, %ymm0;
 	vpshufb %ymm14, %ymm0, %ymm13;
 	vmovdqu %ymm13, 15 * 32(%rax);
@@ -1159,7 +1159,7 @@ ENTRY(camellia_ctr_32way)
 
 	/* inpack32_pre: */
 	vpbroadcastq (key_table)(CTX), %ymm15;
-	vpshufb .Lpack_bswap, %ymm15, %ymm15;
+	vpshufb .Lpack_bswap(%rip), %ymm15, %ymm15;
 	vpxor %ymm0, %ymm15, %ymm0;
 	vpxor %ymm1, %ymm15, %ymm1;
 	vpxor %ymm2, %ymm15, %ymm2;
@@ -1243,13 +1243,13 @@ camellia_xts_crypt_32way:
 	subq $(16 * 32), %rsp;
 	movq %rsp, %rax;
 
-	vbroadcasti128 .Lxts_gf128mul_and_shl1_mask_0, %ymm12;
+	vbroadcasti128 .Lxts_gf128mul_and_shl1_mask_0(%rip), %ymm12;
 
 	/* load IV and construct second IV */
 	vmovdqu (%rcx), %xmm0;
 	vmovdqa %xmm0, %xmm15;
 	gf128mul_x_ble(%xmm0, %xmm12, %xmm13);
-	vbroadcasti128 .Lxts_gf128mul_and_shl1_mask_1, %ymm13;
+	vbroadcasti128 .Lxts_gf128mul_and_shl1_mask_1(%rip), %ymm13;
 	vinserti128 $1, %xmm0, %ymm15, %ymm0;
 	vpxor 0 * 32(%rdx), %ymm0, %ymm15;
 	vmovdqu %ymm15, 15 * 32(%rax);
@@ -1326,7 +1326,7 @@ camellia_xts_crypt_32way:
 
 	/* inpack32_pre: */
 	vpbroadcastq (key_table)(CTX, %r8, 8), %ymm15;
-	vpshufb .Lpack_bswap, %ymm15, %ymm15;
+	vpshufb .Lpack_bswap(%rip), %ymm15, %ymm15;
 	vpxor 0 * 32(%rax), %ymm15, %ymm0;
 	vpxor %ymm1, %ymm15, %ymm1;
 	vpxor %ymm2, %ymm15, %ymm2;
@@ -1384,7 +1384,7 @@ ENTRY(camellia_xts_enc_32way)
 
 	xorl %r8d, %r8d; /* input whitening key, 0 for enc */
 
-	leaq __camellia_enc_blk32, %r9;
+	leaq __camellia_enc_blk32(%rip), %r9;
 
 	jmp camellia_xts_crypt_32way;
 ENDPROC(camellia_xts_enc_32way)
@@ -1402,7 +1402,7 @@ ENTRY(camellia_xts_dec_32way)
 	movl $24, %eax;
 	cmovel %eax, %r8d;  /* input whitening key, last for dec */
 
-	leaq __camellia_dec_blk32, %r9;
+	leaq __camellia_dec_blk32(%rip), %r9;
 
 	jmp camellia_xts_crypt_32way;
 ENDPROC(camellia_xts_dec_32way)
diff --git a/arch/x86/crypto/camellia-x86_64-asm_64.S b/arch/x86/crypto/camellia-x86_64-asm_64.S
index 95ba6956a7f6..ef1137406959 100644
--- a/arch/x86/crypto/camellia-x86_64-asm_64.S
+++ b/arch/x86/crypto/camellia-x86_64-asm_64.S
@@ -92,11 +92,13 @@
 #define RXORbl %r9b
 
 #define xor2ror16(T0, T1, tmp1, tmp2, ab, dst) \
+	leaq T0(%rip), 			tmp1; \
 	movzbl ab ## bl,		tmp2 ## d; \
+	xorq (tmp1, tmp2, 8),		dst; \
+	leaq T1(%rip), 			tmp2; \
 	movzbl ab ## bh,		tmp1 ## d; \
-	rorq $16,			ab; \
-	xorq T0(, tmp2, 8),		dst; \
-	xorq T1(, tmp1, 8),		dst;
+	xorq (tmp2, tmp1, 8),		dst; \
+	rorq $16,			ab;
 
 /**********************************************************************
   1-way camellia
diff --git a/arch/x86/crypto/cast5-avx-x86_64-asm_64.S b/arch/x86/crypto/cast5-avx-x86_64-asm_64.S
index 86107c961bb4..64eb5c87d04a 100644
--- a/arch/x86/crypto/cast5-avx-x86_64-asm_64.S
+++ b/arch/x86/crypto/cast5-avx-x86_64-asm_64.S
@@ -98,16 +98,20 @@
 
 
 #define lookup_32bit(src, dst, op1, op2, op3, interleave_op, il_reg) \
-	movzbl		src ## bh,     RID1d;    \
-	movzbl		src ## bl,     RID2d;    \
-	shrq $16,	src;                     \
-	movl		s1(, RID1, 4), dst ## d; \
-	op1		s2(, RID2, 4), dst ## d; \
-	movzbl		src ## bh,     RID1d;    \
-	movzbl		src ## bl,     RID2d;    \
-	interleave_op(il_reg);			 \
-	op2		s3(, RID1, 4), dst ## d; \
-	op3		s4(, RID2, 4), dst ## d;
+	movzbl		src ## bh,       RID1d;    \
+	leaq		s1(%rip),        RID2;     \
+	movl		(RID2, RID1, 4), dst ## d; \
+	movzbl		src ## bl,       RID2d;    \
+	leaq		s2(%rip),        RID1;     \
+	op1		(RID1, RID2, 4), dst ## d; \
+	shrq $16,	src;                       \
+	movzbl		src ## bh,     RID1d;      \
+	leaq		s3(%rip),        RID2;     \
+	op2		(RID2, RID1, 4), dst ## d; \
+	movzbl		src ## bl,     RID2d;      \
+	leaq		s4(%rip),        RID1;     \
+	op3		(RID1, RID2, 4), dst ## d; \
+	interleave_op(il_reg);
 
 #define dummy(d) /* do nothing */
 
@@ -166,15 +170,15 @@
 	subround(l ## 3, r ## 3, l ## 4, r ## 4, f);
 
 #define enc_preload_rkr() \
-	vbroadcastss	.L16_mask,                RKR;      \
+	vbroadcastss	.L16_mask(%rip),          RKR;      \
 	/* add 16-bit rotation to key rotations (mod 32) */ \
 	vpxor		kr(CTX),                  RKR, RKR;
 
 #define dec_preload_rkr() \
-	vbroadcastss	.L16_mask,                RKR;      \
+	vbroadcastss	.L16_mask(%rip),          RKR;      \
 	/* add 16-bit rotation to key rotations (mod 32) */ \
 	vpxor		kr(CTX),                  RKR, RKR; \
-	vpshufb		.Lbswap128_mask,          RKR, RKR;
+	vpshufb		.Lbswap128_mask(%rip),    RKR, RKR;
 
 #define transpose_2x4(x0, x1, t0, t1) \
 	vpunpckldq		x1, x0, t0; \
@@ -251,9 +255,9 @@ __cast5_enc_blk16:
 
 	movq %rdi, CTX;
 
-	vmovdqa .Lbswap_mask, RKM;
-	vmovd .Lfirst_mask, R1ST;
-	vmovd .L32_mask, R32;
+	vmovdqa .Lbswap_mask(%rip), RKM;
+	vmovd .Lfirst_mask(%rip), R1ST;
+	vmovd .L32_mask(%rip), R32;
 	enc_preload_rkr();
 
 	inpack_blocks(RL1, RR1, RTMP, RX, RKM);
@@ -287,7 +291,7 @@ __cast5_enc_blk16:
 	popq %rbx;
 	popq %r15;
 
-	vmovdqa .Lbswap_mask, RKM;
+	vmovdqa .Lbswap_mask(%rip), RKM;
 
 	outunpack_blocks(RR1, RL1, RTMP, RX, RKM);
 	outunpack_blocks(RR2, RL2, RTMP, RX, RKM);
@@ -325,9 +329,9 @@ __cast5_dec_blk16:
 
 	movq %rdi, CTX;
 
-	vmovdqa .Lbswap_mask, RKM;
-	vmovd .Lfirst_mask, R1ST;
-	vmovd .L32_mask, R32;
+	vmovdqa .Lbswap_mask(%rip), RKM;
+	vmovd .Lfirst_mask(%rip), R1ST;
+	vmovd .L32_mask(%rip), R32;
 	dec_preload_rkr();
 
 	inpack_blocks(RL1, RR1, RTMP, RX, RKM);
@@ -358,7 +362,7 @@ __cast5_dec_blk16:
 	round(RL, RR, 1, 2);
 	round(RR, RL, 0, 1);
 
-	vmovdqa .Lbswap_mask, RKM;
+	vmovdqa .Lbswap_mask(%rip), RKM;
 	popq %rbx;
 	popq %r15;
 
@@ -521,8 +525,8 @@ ENTRY(cast5_ctr_16way)
 
 	vpcmpeqd RKR, RKR, RKR;
 	vpaddq RKR, RKR, RKR; /* low: -2, high: -2 */
-	vmovdqa .Lbswap_iv_mask, R1ST;
-	vmovdqa .Lbswap128_mask, RKM;
+	vmovdqa .Lbswap_iv_mask(%rip), R1ST;
+	vmovdqa .Lbswap128_mask(%rip), RKM;
 
 	/* load IV and byteswap */
 	vmovq (%rcx), RX;
diff --git a/arch/x86/crypto/cast6-avx-x86_64-asm_64.S b/arch/x86/crypto/cast6-avx-x86_64-asm_64.S
index 7f30b6f0d72c..da1b7e4a23e4 100644
--- a/arch/x86/crypto/cast6-avx-x86_64-asm_64.S
+++ b/arch/x86/crypto/cast6-avx-x86_64-asm_64.S
@@ -98,16 +98,20 @@
 
 
 #define lookup_32bit(src, dst, op1, op2, op3, interleave_op, il_reg) \
-	movzbl		src ## bh,     RID1d;    \
-	movzbl		src ## bl,     RID2d;    \
-	shrq $16,	src;                     \
-	movl		s1(, RID1, 4), dst ## d; \
-	op1		s2(, RID2, 4), dst ## d; \
-	movzbl		src ## bh,     RID1d;    \
-	movzbl		src ## bl,     RID2d;    \
-	interleave_op(il_reg);			 \
-	op2		s3(, RID1, 4), dst ## d; \
-	op3		s4(, RID2, 4), dst ## d;
+	movzbl		src ## bh,       RID1d;    \
+	leaq		s1(%rip),        RID2;     \
+	movl		(RID2, RID1, 4), dst ## d; \
+	movzbl		src ## bl,       RID2d;    \
+	leaq		s2(%rip),        RID1;     \
+	op1		(RID1, RID2, 4), dst ## d; \
+	shrq $16,	src;                       \
+	movzbl		src ## bh,     RID1d;      \
+	leaq		s3(%rip),        RID2;     \
+	op2		(RID2, RID1, 4), dst ## d; \
+	movzbl		src ## bl,     RID2d;      \
+	leaq		s4(%rip),        RID1;     \
+	op3		(RID1, RID2, 4), dst ## d; \
+	interleave_op(il_reg);
 
 #define dummy(d) /* do nothing */
 
@@ -190,10 +194,10 @@
 	qop(RD, RC, 1);
 
 #define shuffle(mask) \
-	vpshufb		mask,            RKR, RKR;
+	vpshufb		mask(%rip),            RKR, RKR;
 
 #define preload_rkr(n, do_mask, mask) \
-	vbroadcastss	.L16_mask,                RKR;      \
+	vbroadcastss	.L16_mask(%rip),          RKR;      \
 	/* add 16-bit rotation to key rotations (mod 32) */ \
 	vpxor		(kr+n*16)(CTX),           RKR, RKR; \
 	do_mask(mask);
@@ -275,9 +279,9 @@ __cast6_enc_blk8:
 
 	movq %rdi, CTX;
 
-	vmovdqa .Lbswap_mask, RKM;
-	vmovd .Lfirst_mask, R1ST;
-	vmovd .L32_mask, R32;
+	vmovdqa .Lbswap_mask(%rip), RKM;
+	vmovd .Lfirst_mask(%rip), R1ST;
+	vmovd .L32_mask(%rip), R32;
 
 	inpack_blocks(RA1, RB1, RC1, RD1, RTMP, RX, RKRF, RKM);
 	inpack_blocks(RA2, RB2, RC2, RD2, RTMP, RX, RKRF, RKM);
@@ -301,7 +305,7 @@ __cast6_enc_blk8:
 	popq %rbx;
 	popq %r15;
 
-	vmovdqa .Lbswap_mask, RKM;
+	vmovdqa .Lbswap_mask(%rip), RKM;
 
 	outunpack_blocks(RA1, RB1, RC1, RD1, RTMP, RX, RKRF, RKM);
 	outunpack_blocks(RA2, RB2, RC2, RD2, RTMP, RX, RKRF, RKM);
@@ -323,9 +327,9 @@ __cast6_dec_blk8:
 
 	movq %rdi, CTX;
 
-	vmovdqa .Lbswap_mask, RKM;
-	vmovd .Lfirst_mask, R1ST;
-	vmovd .L32_mask, R32;
+	vmovdqa .Lbswap_mask(%rip), RKM;
+	vmovd .Lfirst_mask(%rip), R1ST;
+	vmovd .L32_mask(%rip), R32;
 
 	inpack_blocks(RA1, RB1, RC1, RD1, RTMP, RX, RKRF, RKM);
 	inpack_blocks(RA2, RB2, RC2, RD2, RTMP, RX, RKRF, RKM);
@@ -349,7 +353,7 @@ __cast6_dec_blk8:
 	popq %rbx;
 	popq %r15;
 
-	vmovdqa .Lbswap_mask, RKM;
+	vmovdqa .Lbswap_mask(%rip), RKM;
 	outunpack_blocks(RA1, RB1, RC1, RD1, RTMP, RX, RKRF, RKM);
 	outunpack_blocks(RA2, RB2, RC2, RD2, RTMP, RX, RKRF, RKM);
 
diff --git a/arch/x86/crypto/des3_ede-asm_64.S b/arch/x86/crypto/des3_ede-asm_64.S
index 8e49ce117494..4bbd3ec78df5 100644
--- a/arch/x86/crypto/des3_ede-asm_64.S
+++ b/arch/x86/crypto/des3_ede-asm_64.S
@@ -138,21 +138,29 @@
 	movzbl RW0bl, RT2d; \
 	movzbl RW0bh, RT3d; \
 	shrq $16, RW0; \
-	movq s8(, RT0, 8), RT0; \
-	xorq s6(, RT1, 8), to; \
+	leaq s8(%rip), RW1; \
+	movq (RW1, RT0, 8), RT0; \
+	leaq s6(%rip), RW1; \
+	xorq (RW1, RT1, 8), to; \
 	movzbl RW0bl, RL1d; \
 	movzbl RW0bh, RT1d; \
 	shrl $16, RW0d; \
-	xorq s4(, RT2, 8), RT0; \
-	xorq s2(, RT3, 8), to; \
+	leaq s4(%rip), RW1; \
+	xorq (RW1, RT2, 8), RT0; \
+	leaq s2(%rip), RW1; \
+	xorq (RW1, RT3, 8), to; \
 	movzbl RW0bl, RT2d; \
 	movzbl RW0bh, RT3d; \
-	xorq s7(, RL1, 8), RT0; \
-	xorq s5(, RT1, 8), to; \
-	xorq s3(, RT2, 8), RT0; \
+	leaq s7(%rip), RW1; \
+	xorq (RW1, RL1, 8), RT0; \
+	leaq s5(%rip), RW1; \
+	xorq (RW1, RT1, 8), to; \
+	leaq s3(%rip), RW1; \
+	xorq (RW1, RT2, 8), RT0; \
 	load_next_key(n, RW0); \
 	xorq RT0, to; \
-	xorq s1(, RT3, 8), to; \
+	leaq s1(%rip), RW1; \
+	xorq (RW1, RT3, 8), to; \
 
 #define load_next_key(n, RWx) \
 	movq (((n) + 1) * 8)(CTX), RWx;
@@ -364,65 +372,89 @@ ENDPROC(des3_ede_x86_64_crypt_blk)
 	movzbl RW0bl, RT3d; \
 	movzbl RW0bh, RT1d; \
 	shrq $16, RW0; \
-	xorq s8(, RT3, 8), to##0; \
-	xorq s6(, RT1, 8), to##0; \
+	leaq s8(%rip), RT2; \
+	xorq (RT2, RT3, 8), to##0; \
+	leaq s6(%rip), RT2; \
+	xorq (RT2, RT1, 8), to##0; \
 	movzbl RW0bl, RT3d; \
 	movzbl RW0bh, RT1d; \
 	shrq $16, RW0; \
-	xorq s4(, RT3, 8), to##0; \
-	xorq s2(, RT1, 8), to##0; \
+	leaq s4(%rip), RT2; \
+	xorq (RT2, RT3, 8), to##0; \
+	leaq s2(%rip), RT2; \
+	xorq (RT2, RT1, 8), to##0; \
 	movzbl RW0bl, RT3d; \
 	movzbl RW0bh, RT1d; \
 	shrl $16, RW0d; \
-	xorq s7(, RT3, 8), to##0; \
-	xorq s5(, RT1, 8), to##0; \
+	leaq s7(%rip), RT2; \
+	xorq (RT2, RT3, 8), to##0; \
+	leaq s5(%rip), RT2; \
+	xorq (RT2, RT1, 8), to##0; \
 	movzbl RW0bl, RT3d; \
 	movzbl RW0bh, RT1d; \
 	load_next_key(n, RW0); \
-	xorq s3(, RT3, 8), to##0; \
-	xorq s1(, RT1, 8), to##0; \
+	leaq s3(%rip), RT2; \
+	xorq (RT2, RT3, 8), to##0; \
+	leaq s1(%rip), RT2; \
+	xorq (RT2, RT1, 8), to##0; \
 		xorq from##1, RW1; \
 		movzbl RW1bl, RT3d; \
 		movzbl RW1bh, RT1d; \
 		shrq $16, RW1; \
-		xorq s8(, RT3, 8), to##1; \
-		xorq s6(, RT1, 8), to##1; \
+		leaq s8(%rip), RT2; \
+		xorq (RT2, RT3, 8), to##1; \
+		leaq s6(%rip), RT2; \
+		xorq (RT2, RT1, 8), to##1; \
 		movzbl RW1bl, RT3d; \
 		movzbl RW1bh, RT1d; \
 		shrq $16, RW1; \
-		xorq s4(, RT3, 8), to##1; \
-		xorq s2(, RT1, 8), to##1; \
+		leaq s4(%rip), RT2; \
+		xorq (RT2, RT3, 8), to##1; \
+		leaq s2(%rip), RT2; \
+		xorq (RT2, RT1, 8), to##1; \
 		movzbl RW1bl, RT3d; \
 		movzbl RW1bh, RT1d; \
 		shrl $16, RW1d; \
-		xorq s7(, RT3, 8), to##1; \
-		xorq s5(, RT1, 8), to##1; \
+		leaq s7(%rip), RT2; \
+		xorq (RT2, RT3, 8), to##1; \
+		leaq s5(%rip), RT2; \
+		xorq (RT2, RT1, 8), to##1; \
 		movzbl RW1bl, RT3d; \
 		movzbl RW1bh, RT1d; \
 		do_movq(RW0, RW1); \
-		xorq s3(, RT3, 8), to##1; \
-		xorq s1(, RT1, 8), to##1; \
+		leaq s3(%rip), RT2; \
+		xorq (RT2, RT3, 8), to##1; \
+		leaq s1(%rip), RT2; \
+		xorq (RT2, RT1, 8), to##1; \
 			xorq from##2, RW2; \
 			movzbl RW2bl, RT3d; \
 			movzbl RW2bh, RT1d; \
 			shrq $16, RW2; \
-			xorq s8(, RT3, 8), to##2; \
-			xorq s6(, RT1, 8), to##2; \
+			leaq s8(%rip), RT2; \
+			xorq (RT2, RT3, 8), to##2; \
+			leaq s6(%rip), RT2; \
+			xorq (RT2, RT1, 8), to##2; \
 			movzbl RW2bl, RT3d; \
 			movzbl RW2bh, RT1d; \
 			shrq $16, RW2; \
-			xorq s4(, RT3, 8), to##2; \
-			xorq s2(, RT1, 8), to##2; \
+			leaq s4(%rip), RT2; \
+			xorq (RT2, RT3, 8), to##2; \
+			leaq s2(%rip), RT2; \
+			xorq (RT2, RT1, 8), to##2; \
 			movzbl RW2bl, RT3d; \
 			movzbl RW2bh, RT1d; \
 			shrl $16, RW2d; \
-			xorq s7(, RT3, 8), to##2; \
-			xorq s5(, RT1, 8), to##2; \
+			leaq s7(%rip), RT2; \
+			xorq (RT2, RT3, 8), to##2; \
+			leaq s5(%rip), RT2; \
+			xorq (RT2, RT1, 8), to##2; \
 			movzbl RW2bl, RT3d; \
 			movzbl RW2bh, RT1d; \
 			do_movq(RW0, RW2); \
-			xorq s3(, RT3, 8), to##2; \
-			xorq s1(, RT1, 8), to##2;
+			leaq s3(%rip), RT2; \
+			xorq (RT2, RT3, 8), to##2; \
+			leaq s1(%rip), RT2; \
+			xorq (RT2, RT1, 8), to##2;
 
 #define __movq(src, dst) \
 	movq src, dst;
diff --git a/arch/x86/crypto/ghash-clmulni-intel_asm.S b/arch/x86/crypto/ghash-clmulni-intel_asm.S
index f94375a8dcd1..d56a281221fb 100644
--- a/arch/x86/crypto/ghash-clmulni-intel_asm.S
+++ b/arch/x86/crypto/ghash-clmulni-intel_asm.S
@@ -97,7 +97,7 @@ ENTRY(clmul_ghash_mul)
 	FRAME_BEGIN
 	movups (%rdi), DATA
 	movups (%rsi), SHASH
-	movaps .Lbswap_mask, BSWAP
+	movaps .Lbswap_mask(%rip), BSWAP
 	PSHUFB_XMM BSWAP DATA
 	call __clmul_gf128mul_ble
 	PSHUFB_XMM BSWAP DATA
@@ -114,7 +114,7 @@ ENTRY(clmul_ghash_update)
 	FRAME_BEGIN
 	cmp $16, %rdx
 	jb .Lupdate_just_ret	# check length
-	movaps .Lbswap_mask, BSWAP
+	movaps .Lbswap_mask(%rip), BSWAP
 	movups (%rdi), DATA
 	movups (%rcx), SHASH
 	PSHUFB_XMM BSWAP DATA
diff --git a/arch/x86/crypto/glue_helper-asm-avx.S b/arch/x86/crypto/glue_helper-asm-avx.S
index 02ee2308fb38..8a49ab1699ef 100644
--- a/arch/x86/crypto/glue_helper-asm-avx.S
+++ b/arch/x86/crypto/glue_helper-asm-avx.S
@@ -54,7 +54,7 @@
 #define load_ctr_8way(iv, bswap, x0, x1, x2, x3, x4, x5, x6, x7, t0, t1, t2) \
 	vpcmpeqd t0, t0, t0; \
 	vpsrldq $8, t0, t0; /* low: -1, high: 0 */ \
-	vmovdqa bswap, t1; \
+	vmovdqa bswap(%rip), t1; \
 	\
 	/* load IV and byteswap */ \
 	vmovdqu (iv), x7; \
@@ -99,7 +99,7 @@
 
 #define load_xts_8way(iv, src, dst, x0, x1, x2, x3, x4, x5, x6, x7, tiv, t0, \
 		      t1, xts_gf128mul_and_shl1_mask) \
-	vmovdqa xts_gf128mul_and_shl1_mask, t0; \
+	vmovdqa xts_gf128mul_and_shl1_mask(%rip), t0; \
 	\
 	/* load IV */ \
 	vmovdqu (iv), tiv; \
diff --git a/arch/x86/crypto/glue_helper-asm-avx2.S b/arch/x86/crypto/glue_helper-asm-avx2.S
index a53ac11dd385..e04c80467bd2 100644
--- a/arch/x86/crypto/glue_helper-asm-avx2.S
+++ b/arch/x86/crypto/glue_helper-asm-avx2.S
@@ -67,7 +67,7 @@
 	vmovdqu (iv), t2x; \
 	vmovdqa t2x, t3x; \
 	inc_le128(t2x, t0x, t1x); \
-	vbroadcasti128 bswap, t1; \
+	vbroadcasti128 bswap(%rip), t1; \
 	vinserti128 $1, t2x, t3, t2; /* ab: le0 ; cd: le1 */ \
 	vpshufb t1, t2, x0; \
 	\
@@ -124,13 +124,13 @@
 		       tivx, t0, t0x, t1, t1x, t2, t2x, t3, \
 		       xts_gf128mul_and_shl1_mask_0, \
 		       xts_gf128mul_and_shl1_mask_1) \
-	vbroadcasti128 xts_gf128mul_and_shl1_mask_0, t1; \
+	vbroadcasti128 xts_gf128mul_and_shl1_mask_0(%rip), t1; \
 	\
 	/* load IV and construct second IV */ \
 	vmovdqu (iv), tivx; \
 	vmovdqa tivx, t0x; \
 	gf128mul_x_ble(tivx, t1x, t2x); \
-	vbroadcasti128 xts_gf128mul_and_shl1_mask_1, t2; \
+	vbroadcasti128 xts_gf128mul_and_shl1_mask_1(%rip), t2; \
 	vinserti128 $1, tivx, t0, tiv; \
 	vpxor (0*32)(src), tiv, x0; \
 	vmovdqu tiv, (0*32)(dst); \
diff --git a/arch/x86/crypto/sha256-avx2-asm.S b/arch/x86/crypto/sha256-avx2-asm.S
index 1420db15dcdd..2ced4b2f6c76 100644
--- a/arch/x86/crypto/sha256-avx2-asm.S
+++ b/arch/x86/crypto/sha256-avx2-asm.S
@@ -588,37 +588,42 @@ last_block_enter:
 	mov	INP, _INP(%rsp)
 
 	## schedule 48 input dwords, by doing 3 rounds of 12 each
-	xor	SRND, SRND
+	leaq	K256(%rip), SRND
+	## loop1 upper bound
+	leaq	K256+3*4*32(%rip), INP
 
 .align 16
 loop1:
-	vpaddd	K256+0*32(SRND), X0, XFER
+	vpaddd	0*32(SRND), X0, XFER
 	vmovdqa XFER, 0*32+_XFER(%rsp, SRND)
 	FOUR_ROUNDS_AND_SCHED	_XFER + 0*32
 
-	vpaddd	K256+1*32(SRND), X0, XFER
+	vpaddd	1*32(SRND), X0, XFER
 	vmovdqa XFER, 1*32+_XFER(%rsp, SRND)
 	FOUR_ROUNDS_AND_SCHED	_XFER + 1*32
 
-	vpaddd	K256+2*32(SRND), X0, XFER
+	vpaddd	2*32(SRND), X0, XFER
 	vmovdqa XFER, 2*32+_XFER(%rsp, SRND)
 	FOUR_ROUNDS_AND_SCHED	_XFER + 2*32
 
-	vpaddd	K256+3*32(SRND), X0, XFER
+	vpaddd	3*32(SRND), X0, XFER
 	vmovdqa XFER, 3*32+_XFER(%rsp, SRND)
 	FOUR_ROUNDS_AND_SCHED	_XFER + 3*32
 
 	add	$4*32, SRND
-	cmp	$3*4*32, SRND
+	cmp	INP, SRND
 	jb	loop1
 
+	## loop2 upper bound
+	leaq	K256+4*4*32(%rip), INP
+
 loop2:
 	## Do last 16 rounds with no scheduling
-	vpaddd	K256+0*32(SRND), X0, XFER
+	vpaddd	0*32(SRND), X0, XFER
 	vmovdqa XFER, 0*32+_XFER(%rsp, SRND)
 	DO_4ROUNDS	_XFER + 0*32
 
-	vpaddd	K256+1*32(SRND), X1, XFER
+	vpaddd	1*32(SRND), X1, XFER
 	vmovdqa XFER, 1*32+_XFER(%rsp, SRND)
 	DO_4ROUNDS	_XFER + 1*32
 	add	$2*32, SRND
@@ -626,7 +631,7 @@ loop2:
 	vmovdqa	X2, X0
 	vmovdqa	X3, X1
 
-	cmp	$4*4*32, SRND
+	cmp	INP, SRND
 	jb	loop2
 
 	mov	_CTX(%rsp), CTX
-- 
2.16.2.660.g709887971b-goog

[PATCH v2 02/27] x86: Use symbol name on bug table for PIE support

[Thomas Garnier]

Replace the %c constraint with %P. The %c is incompatible with PIE
because it implies an immediate value whereas %P reference a symbol.

Position Independent Executable (PIE) support will allow to extended the
KASLR randomization range below the -2G memory limit.

Signed-off-by: Thomas Garnier <thgarnie@google.com>
---
 arch/x86/include/asm/bug.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/bug.h b/arch/x86/include/asm/bug.h
index 6804d6642767..3d690a4abf50 100644
--- a/arch/x86/include/asm/bug.h
+++ b/arch/x86/include/asm/bug.h
@@ -35,7 +35,7 @@ do {									\
 	asm volatile("1:\t" ins "\n"					\
 		     ".pushsection __bug_table,\"aw\"\n"		\
 		     "2:\t" __BUG_REL(1b) "\t# bug_entry::bug_addr\n"	\
-		     "\t"  __BUG_REL(%c0) "\t# bug_entry::file\n"	\
+		     "\t"  __BUG_REL(%P0) "\t# bug_entry::file\n"	\
 		     "\t.word %c1"        "\t# bug_entry::line\n"	\
 		     "\t.word %c2"        "\t# bug_entry::flags\n"	\
 		     "\t.org 2b+%c3\n"					\
-- 
2.16.2.660.g709887971b-goog

[PATCH v2 03/27] x86: Use symbol name in jump table for PIE support

[Thomas Garnier]

Replace the %c constraint with %P. The %c is incompatible with PIE
because it implies an immediate value whereas %P reference a symbol.

Position Independent Executable (PIE) support will allow to extended the
KASLR randomization range below the -2G memory limit.

Signed-off-by: Thomas Garnier <thgarnie@google.com>
---
 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 8c0de4282659..dfdcdc39604a 100644
--- a/arch/x86/include/asm/jump_label.h
+++ b/arch/x86/include/asm/jump_label.h
@@ -37,9 +37,9 @@ static __always_inline bool arch_static_branch(struct static_key *key, bool bran
 		".byte " __stringify(STATIC_KEY_INIT_NOP) "\n\t"
 		".pushsection __jump_table,  \"aw\" \n\t"
 		_ASM_ALIGN "\n\t"
-		_ASM_PTR "1b, %l[l_yes], %c0 + %c1 \n\t"
+		_ASM_PTR "1b, %l[l_yes], %P0 \n\t"
 		".popsection \n\t"
-		: :  "i" (key), "i" (branch) : : l_yes);
+		: :  "X" (&((char *)key)[branch]) : : l_yes);
 
 	return false;
 l_yes:
@@ -53,9 +53,9 @@ static __always_inline bool arch_static_branch_jump(struct static_key *key, bool
 		"2:\n\t"
 		".pushsection __jump_table,  \"aw\" \n\t"
 		_ASM_ALIGN "\n\t"
-		_ASM_PTR "1b, %l[l_yes], %c0 + %c1 \n\t"
+		_ASM_PTR "1b, %l[l_yes], %P0 \n\t"
 		".popsection \n\t"
-		: :  "i" (key), "i" (branch) : : l_yes);
+		: :  "X" (&((char *)key)[branch]) : : l_yes);
 
 	return false;
 l_yes:
-- 
2.16.2.660.g709887971b-goog

[PATCH v2 04/27] x86: Add macro to get symbol address for PIE support

[Thomas Garnier]

Add a new _ASM_MOVABS macro to fetch a symbol address. It will be used
to replace "_ASM_MOV $<symbol>, %dst" code construct that are not compatible
with PIE.

Signed-off-by: Thomas Garnier <thgarnie@google.com>
---
 arch/x86/include/asm/asm.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/x86/include/asm/asm.h b/arch/x86/include/asm/asm.h
index 386a6900e206..653d8b82f015 100644
--- a/arch/x86/include/asm/asm.h
+++ b/arch/x86/include/asm/asm.h
@@ -30,6 +30,7 @@
 #define _ASM_ALIGN	__ASM_SEL(.balign 4, .balign 8)
 
 #define _ASM_MOV	__ASM_SIZE(mov)
+#define _ASM_MOVABS	__ASM_SEL(movl, movabsq)
 #define _ASM_INC	__ASM_SIZE(inc)
 #define _ASM_DEC	__ASM_SIZE(dec)
 #define _ASM_ADD	__ASM_SIZE(add)
-- 
2.16.2.660.g709887971b-goog

[PATCH v2 05/27] x86: relocate_kernel - Adapt assembly for PIE support

[Thomas Garnier]

Change the assembly code to use only relative references of symbols for the
kernel to be PIE compatible.

Position Independent Executable (PIE) support will allow to extended the
KASLR randomization range below the -2G memory limit.

Signed-off-by: Thomas Garnier <thgarnie@google.com>
---
 arch/x86/kernel/relocate_kernel_64.S | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/relocate_kernel_64.S b/arch/x86/kernel/relocate_kernel_64.S
index 11eda21eb697..a7227dfe1a2b 100644
--- a/arch/x86/kernel/relocate_kernel_64.S
+++ b/arch/x86/kernel/relocate_kernel_64.S
@@ -208,9 +208,11 @@ identity_mapped:
 	movq	%rax, %cr3
 	lea	PAGE_SIZE(%r8), %rsp
 	call	swap_pages
-	movq	$virtual_mapped, %rax
-	pushq	%rax
-	ret
+	jmp	*virtual_mapped_addr(%rip)
+
+	/* Absolute value for PIE support */
+virtual_mapped_addr:
+	.quad virtual_mapped
 
 virtual_mapped:
 	movq	RSP(%r8), %rsp
-- 
2.16.2.660.g709887971b-goog

[PATCH v2 06/27] x86/entry/64: Adapt assembly for PIE support

[Thomas Garnier]

Change the assembly code to use only relative references of symbols for the
kernel to be PIE compatible.

Position Independent Executable (PIE) support will allow to extended the
KASLR randomization range below the -2G memory limit.

Signed-off-by: Thomas Garnier <thgarnie@google.com>
---
 arch/x86/entry/entry_64.S            | 16 ++++++++++------
 arch/x86/kernel/relocate_kernel_64.S |  8 +++-----
 2 files changed, 13 insertions(+), 11 deletions(-)

diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index bd53c57617e6..c53123468364 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -191,7 +191,7 @@ ENTRY(entry_SYSCALL_64_trampoline)
 	 * spill RDI and restore it in a second-stage trampoline.
 	 */
 	pushq	%rdi
-	movq	$entry_SYSCALL_64_stage2, %rdi
+	movabsq	$entry_SYSCALL_64_stage2, %rdi
 	JMP_NOSPEC %rdi
 END(entry_SYSCALL_64_trampoline)
 
@@ -1275,7 +1275,8 @@ ENTRY(error_entry)
 	movl	%ecx, %eax			/* zero extend */
 	cmpq	%rax, RIP+8(%rsp)
 	je	.Lbstep_iret
-	cmpq	$.Lgs_change, RIP+8(%rsp)
+	leaq	.Lgs_change(%rip), %rcx
+	cmpq	%rcx, RIP+8(%rsp)
 	jne	.Lerror_entry_done
 
 	/*
@@ -1480,10 +1481,10 @@ ENTRY(nmi)
 	 * resume the outer NMI.
 	 */
 
-	movq	$repeat_nmi, %rdx
+	leaq	repeat_nmi(%rip), %rdx
 	cmpq	8(%rsp), %rdx
 	ja	1f
-	movq	$end_repeat_nmi, %rdx
+	leaq	end_repeat_nmi(%rip), %rdx
 	cmpq	8(%rsp), %rdx
 	ja	nested_nmi_out
 1:
@@ -1537,7 +1538,8 @@ nested_nmi:
 	pushq	%rdx
 	pushfq
 	pushq	$__KERNEL_CS
-	pushq	$repeat_nmi
+	leaq	repeat_nmi(%rip), %rdx
+	pushq	%rdx
 
 	/* Put stack back */
 	addq	$(6*8), %rsp
@@ -1576,7 +1578,9 @@ first_nmi:
 	addq	$8, (%rsp)	/* Fix up RSP */
 	pushfq			/* RFLAGS */
 	pushq	$__KERNEL_CS	/* CS */
-	pushq	$1f		/* RIP */
+	pushq	%rax		/* Support Position Independent Code */
+	leaq	1f(%rip), %rax	/* RIP */
+	xchgq	%rax, (%rsp)	/* Restore RAX, put 1f */
 	iretq			/* continues at repeat_nmi below */
 	UNWIND_HINT_IRET_REGS
 1:
diff --git a/arch/x86/kernel/relocate_kernel_64.S b/arch/x86/kernel/relocate_kernel_64.S
index a7227dfe1a2b..0c0fc259a4e2 100644
--- a/arch/x86/kernel/relocate_kernel_64.S
+++ b/arch/x86/kernel/relocate_kernel_64.S
@@ -208,11 +208,9 @@ identity_mapped:
 	movq	%rax, %cr3
 	lea	PAGE_SIZE(%r8), %rsp
 	call	swap_pages
-	jmp	*virtual_mapped_addr(%rip)
-
-	/* Absolute value for PIE support */
-virtual_mapped_addr:
-	.quad virtual_mapped
+	movabsq $virtual_mapped, %rax
+	pushq	%rax
+	ret
 
 virtual_mapped:
 	movq	RSP(%r8), %rsp
-- 
2.16.2.660.g709887971b-goog

Re: [PATCH v2 06/27] x86/entry/64: Adapt assembly for PIE support

[Peter Zijlstra]

On Tue, Mar 13, 2018 at 01:59:24PM -0700, Thomas Garnier wrote:
> @@ -1576,7 +1578,9 @@ first_nmi:
>  	addq	$8, (%rsp)	/* Fix up RSP */
>  	pushfq			/* RFLAGS */
>  	pushq	$__KERNEL_CS	/* CS */
> -	pushq	$1f		/* RIP */
> +	pushq	%rax		/* Support Position Independent Code */
> +	leaq	1f(%rip), %rax	/* RIP */
> +	xchgq	%rax, (%rsp)	/* Restore RAX, put 1f */
>  	iretq			/* continues at repeat_nmi below */
>  	UNWIND_HINT_IRET_REGS
>  1:

Urgh, xchg with a memop has an implicit LOCK prefix.

Re: [PATCH v2 06/27] x86/entry/64: Adapt assembly for PIE support

[Christopher Lameter]

On Wed, 14 Mar 2018, Peter Zijlstra wrote:

> On Tue, Mar 13, 2018 at 01:59:24PM -0700, Thomas Garnier wrote:
> > @@ -1576,7 +1578,9 @@ first_nmi:
> >  	addq	$8, (%rsp)	/* Fix up RSP */
> >  	pushfq			/* RFLAGS */
> >  	pushq	$__KERNEL_CS	/* CS */
> > -	pushq	$1f		/* RIP */
> > +	pushq	%rax		/* Support Position Independent Code */
> > +	leaq	1f(%rip), %rax	/* RIP */
> > +	xchgq	%rax, (%rsp)	/* Restore RAX, put 1f */
> >  	iretq			/* continues at repeat_nmi below */
> >  	UNWIND_HINT_IRET_REGS
> >  1:
>
> Urgh, xchg with a memop has an implicit LOCK prefix.

this_cpu_xchg uses no lock cmpxchg as a replacement to reduce latency.

>From linux/arch/x86/include/asm/percpu.h

/*
 * xchg is implemented using cmpxchg without a lock prefix. xchg is
 * expensive due to the implied lock prefix.  The processor cannot prefetch
 * cachelines if xchg is used.
 */
#define percpu_xchg_op(var, nval)                                       \
({                                                                      \
        typeof(var) pxo_ret__;                                          \
        typeof(var) pxo_new__ = (nval);                                 \
        switch (sizeof(var)) {                                          \
        case 1:                                                         \
                asm("\n\tmov "__percpu_arg(1)",%%al"                    \
                    "\n1:\tcmpxchgb %2, "__percpu_arg(1)                \
                    "\n\tjnz 1b"                                        \
                            : "=&a" (pxo_ret__), "+m" (var)             \
                            : "q" (pxo_new__)                           \
                            : "memory");                                \
                break;                                                  \
        case 2:                                                         \
                asm("\n\tmov "__percpu_arg(1)",%%ax"                    \
                    "\n1:\tcmpxchgw %2, "__percpu_arg(1)                \
                    "\n\tjnz 1b"                                        \
                            : "=&a" (pxo_ret__), "+m" (var)             \
                            : "r" (pxo_new__)                           \
                            : "memory");                                \
                break;                                                  \
        case 4:                                                         \
                asm("\n\tmov "__percpu_arg(1)",%%eax"                   \
                    "\n1:\tcmpxchgl %2, "__percpu_arg(1)                \
                    "\n\tjnz 1b"                                        \
                            : "=&a" (pxo_ret__), "+m" (var)             \
                            : "r" (pxo_new__)                           \
                            : "memory");                                \
                break;                                                  \
        case 8:                                                         \
                asm("\n\tmov "__percpu_arg(1)",%%rax"                   \
                    "\n1:\tcmpxchgq %2, "__percpu_arg(1)                \
                    "\n\tjnz 1b"                                        \
                            : "=&a" (pxo_ret__), "+m" (var)             \
                            : "r" (pxo_new__)                           \
                            : "memory");                                \
                break;                                                  \
        default: __bad_percpu_size();                                   \
        }                                                               \
        pxo_ret__;                                                      \

Re: [PATCH v2 06/27] x86/entry/64: Adapt assembly for PIE support

[Thomas Garnier]

On Wed, Mar 14, 2018 at 8:55 AM Christopher Lameter <cl@linux.com> wrote:



> On Wed, 14 Mar 2018, Peter Zijlstra wrote:

> > On Tue, Mar 13, 2018 at 01:59:24PM -0700, Thomas Garnier wrote:
> > > @@ -1576,7 +1578,9 @@ first_nmi:
> > >     addq    $8, (%rsp)      /* Fix up RSP */
> > >     pushfq                  /* RFLAGS */
> > >     pushq   $__KERNEL_CS    /* CS */
> > > -   pushq   $1f             /* RIP */
> > > +   pushq   %rax            /* Support Position Independent Code */
> > > +   leaq    1f(%rip), %rax  /* RIP */
> > > +   xchgq   %rax, (%rsp)    /* Restore RAX, put 1f */
> > >     iretq                   /* continues at repeat_nmi below */
> > >     UNWIND_HINT_IRET_REGS
> > >  1:
> >
> > Urgh, xchg with a memop has an implicit LOCK prefix.

> this_cpu_xchg uses no lock cmpxchg as a replacement to reduce latency.

Great, I will update my implementation.

Thanks Peter and Christoph.


>  From linux/arch/x86/include/asm/percpu.h

> /*
>   * xchg is implemented using cmpxchg without a lock prefix. xchg is
>   * expensive due to the implied lock prefix.  The processor cannot
prefetch
>   * cachelines if xchg is used.
>   */
> #define percpu_xchg_op(var, nval)                                       \
> ({                                                                      \
>          typeof(var) pxo_ret__;                                          \
>          typeof(var) pxo_new__ = (nval);                                 \
>          switch (sizeof(var)) {                                          \
>          case 1:                                                         \
>                  asm("\n\tmov "__percpu_arg(1)",%%al"                    \
>                      "\n1:\tcmpxchgb %2, "__percpu_arg(1)                \
>                      "\n\tjnz 1b"                                        \
>                              : "=&a" (pxo_ret__), "+m" (var)             \
>                              : "q" (pxo_new__)                           \
>                              : "memory");                                \
>                  break;                                                  \
>          case 2:                                                         \
>                  asm("\n\tmov "__percpu_arg(1)",%%ax"                    \
>                      "\n1:\tcmpxchgw %2, "__percpu_arg(1)                \
>                      "\n\tjnz 1b"                                        \
>                              : "=&a" (pxo_ret__), "+m" (var)             \
>                              : "r" (pxo_new__)                           \
>                              : "memory");                                \
>                  break;                                                  \
>          case 4:                                                         \
>                  asm("\n\tmov "__percpu_arg(1)",%%eax"                   \
>                      "\n1:\tcmpxchgl %2, "__percpu_arg(1)                \
>                      "\n\tjnz 1b"                                        \
>                              : "=&a" (pxo_ret__), "+m" (var)             \
>                              : "r" (pxo_new__)                           \
>                              : "memory");                                \
>                  break;                                                  \
>          case 8:                                                         \
>                  asm("\n\tmov "__percpu_arg(1)",%%rax"                   \
>                      "\n1:\tcmpxchgq %2, "__percpu_arg(1)                \
>                      "\n\tjnz 1b"                                        \
>                              : "=&a" (pxo_ret__), "+m" (var)             \
>                              : "r" (pxo_new__)                           \
>                              : "memory");                                \
>                  break;                                                  \
>          default: __bad_percpu_size();                                   \
>          }                                                               \
>          pxo_ret__;                                                      \




-- 
Thomas

Re: [PATCH v2 06/27] x86/entry/64: Adapt assembly for PIE support

[Paolo Bonzini]

On 14/03/2018 16:54, Christopher Lameter wrote:
>>> +	pushq	%rax		/* Support Position Independent Code */
>>> +	leaq	1f(%rip), %rax	/* RIP */
>>> +	xchgq	%rax, (%rsp)	/* Restore RAX, put 1f */
>>>  	iretq			/* continues at repeat_nmi below */
>>>  	UNWIND_HINT_IRET_REGS
>>>  1:
>> Urgh, xchg with a memop has an implicit LOCK prefix.
> this_cpu_xchg uses no lock cmpxchg as a replacement to reduce latency.

That requires using a second register, since %rax is used as the
comparison source.  At this point it's easier to just push %rax twice:

	pushq %rax
	pushq %rax
	leaq 1f(%ip), %rax
	movq %rax, 8(%rsp)
	popq %rax
	iretq

Paolo

[PATCH v2 07/27] x86: pm-trace - Adapt assembly for PIE support

[Thomas Garnier]

Change assembly to use the new _ASM_MOVABS macro instead of _ASM_MOV for
the assembly to be PIE compatible.

Position Independent Executable (PIE) support will allow to extended the
KASLR randomization range below the -2G memory limit.

Signed-off-by: Thomas Garnier <thgarnie@google.com>
---
 arch/x86/include/asm/pm-trace.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/pm-trace.h b/arch/x86/include/asm/pm-trace.h
index bfa32aa428e5..972070806ce9 100644
--- a/arch/x86/include/asm/pm-trace.h
+++ b/arch/x86/include/asm/pm-trace.h
@@ -8,7 +8,7 @@
 do {								\
 	if (pm_trace_enabled) {					\
 		const void *tracedata;				\
-		asm volatile(_ASM_MOV " $1f,%0\n"		\
+		asm volatile(_ASM_MOVABS " $1f,%0\n"		\
 			     ".section .tracedata,\"a\"\n"	\
 			     "1:\t.word %c1\n\t"		\
 			     _ASM_PTR " %c2\n"			\
-- 
2.16.2.660.g709887971b-goog

[PATCH v2 08/27] x86/CPU: Adapt assembly for PIE support

[Thomas Garnier]

Change the assembly code to use only relative references of symbols for the
kernel to be PIE compatible. Use the new _ASM_MOVABS macro instead of
the 'mov $symbol, %dst' construct.

Position Independent Executable (PIE) support will allow to extended the
KASLR randomization range below the -2G memory limit.

Signed-off-by: Thomas Garnier <thgarnie@google.com>
---
 arch/x86/include/asm/processor.h | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index b0ccd4847a58..1b9488b1018a 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -50,7 +50,7 @@ static inline void *current_text_addr(void)
 {
 	void *pc;
 
-	asm volatile("mov $1f, %0; 1:":"=r" (pc));
+	asm volatile(_ASM_MOVABS " $1f, %0; 1:":"=r" (pc));
 
 	return pc;
 }
@@ -710,6 +710,7 @@ static inline void sync_core(void)
 		: ASM_CALL_CONSTRAINT : : "memory");
 #else
 	unsigned int tmp;
+	unsigned long tmp2;
 
 	asm volatile (
 		UNWIND_HINT_SAVE
@@ -720,11 +721,13 @@ static inline void sync_core(void)
 		"pushfq\n\t"
 		"mov %%cs, %0\n\t"
 		"pushq %q0\n\t"
-		"pushq $1f\n\t"
+		"leaq 1f(%%rip), %1\n\t"
+		"pushq %1\n\t"
 		"iretq\n\t"
 		UNWIND_HINT_RESTORE
 		"1:"
-		: "=&r" (tmp), ASM_CALL_CONSTRAINT : : "cc", "memory");
+		: "=&r" (tmp), "=&r" (tmp2), ASM_CALL_CONSTRAINT
+		: : "cc", "memory");
 #endif
 }
 
-- 
2.16.2.660.g709887971b-goog

[PATCH v2 09/27] x86/acpi: Adapt assembly for PIE support

[Thomas Garnier]

Change the assembly code to use only relative references of symbols for the
kernel to be PIE compatible.

Position Independent Executable (PIE) support will allow to extended the
KASLR randomization range below the -2G memory limit.

Signed-off-by: Thomas Garnier <thgarnie@google.com>
---
 arch/x86/kernel/acpi/wakeup_64.S | 31 ++++++++++++++++---------------
 1 file changed, 16 insertions(+), 15 deletions(-)

diff --git a/arch/x86/kernel/acpi/wakeup_64.S b/arch/x86/kernel/acpi/wakeup_64.S
index 50b8ed0317a3..472659c0f811 100644
--- a/arch/x86/kernel/acpi/wakeup_64.S
+++ b/arch/x86/kernel/acpi/wakeup_64.S
@@ -14,7 +14,7 @@
 	 * Hooray, we are in Long 64-bit mode (but still running in low memory)
 	 */
 ENTRY(wakeup_long64)
-	movq	saved_magic, %rax
+	movq	saved_magic(%rip), %rax
 	movq	$0x123456789abcdef0, %rdx
 	cmpq	%rdx, %rax
 	jne	bogus_64_magic
@@ -25,14 +25,14 @@ ENTRY(wakeup_long64)
 	movw	%ax, %es
 	movw	%ax, %fs
 	movw	%ax, %gs
-	movq	saved_rsp, %rsp
+	movq	saved_rsp(%rip), %rsp
 
-	movq	saved_rbx, %rbx
-	movq	saved_rdi, %rdi
-	movq	saved_rsi, %rsi
-	movq	saved_rbp, %rbp
+	movq	saved_rbx(%rip), %rbx
+	movq	saved_rdi(%rip), %rdi
+	movq	saved_rsi(%rip), %rsi
+	movq	saved_rbp(%rip), %rbp
 
-	movq	saved_rip, %rax
+	movq	saved_rip(%rip), %rax
 	jmp	*%rax
 ENDPROC(wakeup_long64)
 
@@ -45,7 +45,7 @@ ENTRY(do_suspend_lowlevel)
 	xorl	%eax, %eax
 	call	save_processor_state
 
-	movq	$saved_context, %rax
+	leaq	saved_context(%rip), %rax
 	movq	%rsp, pt_regs_sp(%rax)
 	movq	%rbp, pt_regs_bp(%rax)
 	movq	%rsi, pt_regs_si(%rax)
@@ -64,13 +64,14 @@ ENTRY(do_suspend_lowlevel)
 	pushfq
 	popq	pt_regs_flags(%rax)
 
-	movq	$.Lresume_point, saved_rip(%rip)
+	leaq	.Lresume_point(%rip), %rax
+	movq	%rax, saved_rip(%rip)
 
-	movq	%rsp, saved_rsp
-	movq	%rbp, saved_rbp
-	movq	%rbx, saved_rbx
-	movq	%rdi, saved_rdi
-	movq	%rsi, saved_rsi
+	movq	%rsp, saved_rsp(%rip)
+	movq	%rbp, saved_rbp(%rip)
+	movq	%rbx, saved_rbx(%rip)
+	movq	%rdi, saved_rdi(%rip)
+	movq	%rsi, saved_rsi(%rip)
 
 	addq	$8, %rsp
 	movl	$3, %edi
@@ -82,7 +83,7 @@ ENTRY(do_suspend_lowlevel)
 	.align 4
 .Lresume_point:
 	/* We don't restore %rax, it must be 0 anyway */
-	movq	$saved_context, %rax
+	leaq	saved_context(%rip), %rax
 	movq	saved_context_cr4(%rax), %rbx
 	movq	%rbx, %cr4
 	movq	saved_context_cr3(%rax), %rbx
-- 
2.16.2.660.g709887971b-goog

[PATCH v2 10/27] x86/boot/64: Adapt assembly for PIE support

[Thomas Garnier]

Change the assembly code to use only relative references of symbols for the
kernel to be PIE compatible.

Early at boot, the kernel is mapped at a temporary address while preparing
the page table. To know the changes needed for the page table with KASLR,
the boot code calculate the difference between the expected address of the
kernel and the one chosen by KASLR. It does not work with PIE because all
symbols in code are relatives. Instead of getting the future relocated
virtual address, you will get the current temporary mapping. The solution
is using global variables that will be relocated as expected.

Position Independent Executable (PIE) support will allow to extended the
KASLR randomization range below the -2G memory limit.

Signed-off-by: Thomas Garnier <thgarnie@google.com>
---
 arch/x86/kernel/head_64.S | 26 ++++++++++++++++++++------
 1 file changed, 20 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index 48385c1074a5..48652f3ec46a 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -89,8 +89,9 @@ startup_64:
 	popq	%rsi
 
 	/* Form the CR3 value being sure to include the CR3 modifier */
-	addq	$(early_top_pgt - __START_KERNEL_map), %rax
+	addq    _early_top_pgt_offset(%rip), %rax
 	jmp 1f
+
 ENTRY(secondary_startup_64)
 	UNWIND_HINT_EMPTY
 	/*
@@ -119,7 +120,7 @@ ENTRY(secondary_startup_64)
 	popq	%rsi
 
 	/* Form the CR3 value being sure to include the CR3 modifier */
-	addq	$(init_top_pgt - __START_KERNEL_map), %rax
+	addq    _init_top_offset(%rip), %rax
 1:
 
 	/* Enable PAE mode, PGE and LA57 */
@@ -137,7 +138,7 @@ ENTRY(secondary_startup_64)
 	movq	%rax, %cr3
 
 	/* Ensure I am executing from virtual addresses */
-	movq	$1f, %rax
+	movabs  $1f, %rax
 	ANNOTATE_RETPOLINE_SAFE
 	jmp	*%rax
 1:
@@ -234,11 +235,12 @@ ENTRY(secondary_startup_64)
 	 *	REX.W + FF /5 JMP m16:64 Jump far, absolute indirect,
 	 *		address given in m16:64.
 	 */
-	pushq	$.Lafter_lret	# put return address on stack for unwinder
+	leaq	.Lafter_lret(%rip), %rax
+	pushq	%rax		# put return address on stack for unwinder
 	xorq	%rbp, %rbp	# clear frame pointer
-	movq	initial_code(%rip), %rax
+	leaq	initial_code(%rip), %rax
 	pushq	$__KERNEL_CS	# set correct cs
-	pushq	%rax		# target address in negative space
+	pushq	(%rax)		# target address in negative space
 	lretq
 .Lafter_lret:
 END(secondary_startup_64)
@@ -342,6 +344,18 @@ END(early_idt_handler_common)
 GLOBAL(early_recursion_flag)
 	.long 0
 
+	/*
+	 * Position Independent Code takes only relative references in code
+	 * meaning a global variable address is relative to RIP and not its
+	 * future virtual address. Global variables can be used instead as they
+	 * are still relocated on the expected kernel mapping address.
+	 */
+	.align 8
+_early_top_pgt_offset:
+	.quad early_top_pgt - __START_KERNEL_map
+_init_top_offset:
+	.quad init_top_pgt - __START_KERNEL_map
+
 #define NEXT_PAGE(name) \
 	.balign	PAGE_SIZE; \
 GLOBAL(name)
-- 
2.16.2.660.g709887971b-goog

[PATCH v2 11/27] x86/power/64: Adapt assembly for PIE support

[Thomas Garnier]

Change the assembly code to use only relative references of symbols for the
kernel to be PIE compatible.

Position Independent Executable (PIE) support will allow to extended the
KASLR randomization range below the -2G memory limit.

Signed-off-by: Thomas Garnier <thgarnie@google.com>
---
 arch/x86/power/hibernate_asm_64.S | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/power/hibernate_asm_64.S b/arch/x86/power/hibernate_asm_64.S
index ce8da3a0412c..6fdd7bbc3c33 100644
--- a/arch/x86/power/hibernate_asm_64.S
+++ b/arch/x86/power/hibernate_asm_64.S
@@ -24,7 +24,7 @@
 #include <asm/frame.h>
 
 ENTRY(swsusp_arch_suspend)
-	movq	$saved_context, %rax
+	leaq	saved_context(%rip), %rax
 	movq	%rsp, pt_regs_sp(%rax)
 	movq	%rbp, pt_regs_bp(%rax)
 	movq	%rsi, pt_regs_si(%rax)
@@ -115,7 +115,7 @@ ENTRY(restore_registers)
 	movq	%rax, %cr4;  # turn PGE back on
 
 	/* We don't restore %rax, it must be 0 anyway */
-	movq	$saved_context, %rax
+	leaq	saved_context(%rip), %rax
 	movq	pt_regs_sp(%rax), %rsp
 	movq	pt_regs_bp(%rax), %rbp
 	movq	pt_regs_si(%rax), %rsi
-- 
2.16.2.660.g709887971b-goog

[PATCH v2 12/27] x86/paravirt: Adapt assembly for PIE support

[Thomas Garnier]

if PIE is enabled, switch the paravirt assembly constraints to be
compatible. The %c/i constrains generate smaller code so is kept by
default.

Position Independent Executable (PIE) support will allow to extended the
KASLR randomization range below the -2G memory limit.

Signed-off-by: Thomas Garnier <thgarnie@google.com>
---
 arch/x86/include/asm/paravirt_types.h | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/paravirt_types.h b/arch/x86/include/asm/paravirt_types.h
index 180bc0bff0fb..140747a98d94 100644
--- a/arch/x86/include/asm/paravirt_types.h
+++ b/arch/x86/include/asm/paravirt_types.h
@@ -337,9 +337,17 @@ extern struct pv_lock_ops pv_lock_ops;
 #define PARAVIRT_PATCH(x)					\
 	(offsetof(struct paravirt_patch_template, x) / sizeof(void *))
 
+#ifdef CONFIG_X86_PIE
+#define paravirt_opptr_call "a"
+#define paravirt_opptr_type "p"
+#else
+#define paravirt_opptr_call "c"
+#define paravirt_opptr_type "i"
+#endif
+
 #define paravirt_type(op)				\
 	[paravirt_typenum] "i" (PARAVIRT_PATCH(op)),	\
-	[paravirt_opptr] "i" (&(op))
+	[paravirt_opptr] paravirt_opptr_type (&(op))
 #define paravirt_clobber(clobber)		\
 	[paravirt_clobber] "i" (clobber)
 
@@ -395,7 +403,7 @@ int paravirt_disable_iospace(void);
  */
 #define PARAVIRT_CALL					\
 	ANNOTATE_RETPOLINE_SAFE				\
-	"call *%c[paravirt_opptr];"
+	"call *%" paravirt_opptr_call "[paravirt_opptr];"
 
 /*
  * These macros are intended to wrap calls through one of the paravirt
-- 
2.16.2.660.g709887971b-goog

[PATCH v2 13/27] x86/boot/64: Build head64.c as mcmodel large when PIE is enabled

[Thomas Garnier]

The __startup_64 function assumes all symbols have relocated addresses
instead of the current boot virtual address. PIE generated code favor
relative addresses making all virtual and physical address math incorrect.
If PIE is enabled, build head64.c as mcmodel large instead to ensure absolute
references on all memory access. Add a global __force_order variable required
when using a large model with read_cr* functions.

To build head64.c as mcmodel=large, disable the retpoline gcc flags.
This code is used at early boot and removed later, it doesn't need
retpoline mitigation.

Position Independent Executable (PIE) support will allow to extended the
KASLR randomization range below the -2G memory limit.

Signed-off-by: Thomas Garnier <thgarnie@google.com>
---
 arch/x86/kernel/Makefile | 6 ++++++
 arch/x86/kernel/head64.c | 3 +++
 2 files changed, 9 insertions(+)

diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index 29786c87e864..1ff6be34de66 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -22,6 +22,12 @@ CFLAGS_REMOVE_early_printk.o = -pg
 CFLAGS_REMOVE_head64.o = -pg
 endif
 
+ifdef CONFIG_X86_PIE
+# Remove PIE and retpoline flags that are incompatible with mcmodel=large
+CFLAGS_REMOVE_head64.o += -fPIE -mindirect-branch=thunk-extern -mindirect-branch-register
+CFLAGS_head64.o = -mcmodel=large
+endif
+
 KASAN_SANITIZE_head$(BITS).o				:= n
 KASAN_SANITIZE_dumpstack.o				:= n
 KASAN_SANITIZE_dumpstack_$(BITS).o			:= n
diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
index 0c855deee165..2fe60e661227 100644
--- a/arch/x86/kernel/head64.c
+++ b/arch/x86/kernel/head64.c
@@ -64,6 +64,9 @@ EXPORT_SYMBOL(vmemmap_base);
 
 #define __head	__section(.head.text)
 
+/* Required for read_cr3 when building as PIE */
+unsigned long __force_order;
+
 static void __head *fixup_pointer(void *ptr, unsigned long physaddr)
 {
 	return ptr - (void *)_text + (void *)physaddr;
-- 
2.16.2.660.g709887971b-goog

[PATCH v2 14/27] x86/percpu: Adapt percpu for PIE support

[Thomas Garnier]

Perpcu uses a clever design where the .percu ELF section has a virtual
address of zero and the relocation code avoid relocating specific
symbols. It makes the code simple and easily adaptable with or without
SMP support.

This design is incompatible with PIE because generated code always try to
access the zero virtual address relative to the default mapping address.
It becomes impossible when KASLR is configured to go below -2G. This
patch solves this problem by removing the zero mapping and adapting the GS
base to be relative to the expected address. These changes are done only
when PIE is enabled. The original implementation is kept as-is
by default.

The assembly and PER_CPU macros are changed to use relative references
when PIE is enabled.

The KALLSYMS_ABSOLUTE_PERCPU configuration is disabled with PIE given
percpu symbols are not absolute in this case.

Position Independent Executable (PIE) support will allow to extended the
KASLR randomization range below the -2G memory limit.

Signed-off-by: Thomas Garnier <thgarnie@google.com>
---
 arch/x86/entry/calling.h       |  2 +-
 arch/x86/entry/entry_64.S      |  4 ++--
 arch/x86/include/asm/percpu.h  | 25 +++++++++++++++++++------
 arch/x86/kernel/cpu/common.c   |  4 +++-
 arch/x86/kernel/head_64.S      |  4 ++++
 arch/x86/kernel/setup_percpu.c |  2 +-
 arch/x86/kernel/vmlinux.lds.S  | 13 +++++++++++--
 arch/x86/lib/cmpxchg16b_emu.S  |  8 ++++----
 arch/x86/xen/xen-asm.S         | 12 ++++++------
 init/Kconfig                   |  2 +-
 10 files changed, 52 insertions(+), 24 deletions(-)

diff --git a/arch/x86/entry/calling.h b/arch/x86/entry/calling.h
index be63330c5511..7b48d97111b5 100644
--- a/arch/x86/entry/calling.h
+++ b/arch/x86/entry/calling.h
@@ -216,7 +216,7 @@ For 32-bit we have the following conventions - kernel is built with
 .endm
 
 #define THIS_CPU_user_pcid_flush_mask   \
-	PER_CPU_VAR(cpu_tlbstate) + TLB_STATE_user_pcid_flush_mask
+	PER_CPU_VAR(cpu_tlbstate + TLB_STATE_user_pcid_flush_mask)
 
 .macro SWITCH_TO_USER_CR3_NOSTACK scratch_reg:req scratch_reg2:req
 	ALTERNATIVE "jmp .Lend_\@", "", X86_FEATURE_PTI
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index c53123468364..d34794368e20 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -358,7 +358,7 @@ ENTRY(__switch_to_asm)
 
 #ifdef CONFIG_CC_STACKPROTECTOR
 	movq	TASK_stack_canary(%rsi), %rbx
-	movq	%rbx, PER_CPU_VAR(irq_stack_union)+stack_canary_offset
+	movq	%rbx, PER_CPU_VAR(irq_stack_union + stack_canary_offset)
 #endif
 
 #ifdef CONFIG_RETPOLINE
@@ -896,7 +896,7 @@ apicinterrupt IRQ_WORK_VECTOR			irq_work_interrupt		smp_irq_work_interrupt
 /*
  * Exception entry points.
  */
-#define CPU_TSS_IST(x) PER_CPU_VAR(cpu_tss_rw) + (TSS_ist + ((x) - 1) * 8)
+#define CPU_TSS_IST(x) PER_CPU_VAR(cpu_tss_rw + (TSS_ist + ((x) - 1) * 8))
 
 .macro idtentry sym do_sym has_error_code:req paranoid=0 shift_ist=-1
 ENTRY(\sym)
diff --git a/arch/x86/include/asm/percpu.h b/arch/x86/include/asm/percpu.h
index a06b07399d17..7d1271b536ea 100644
--- a/arch/x86/include/asm/percpu.h
+++ b/arch/x86/include/asm/percpu.h
@@ -5,9 +5,11 @@
 #ifdef CONFIG_X86_64
 #define __percpu_seg		gs
 #define __percpu_mov_op		movq
+#define __percpu_rel		(%rip)
 #else
 #define __percpu_seg		fs
 #define __percpu_mov_op		movl
+#define __percpu_rel
 #endif
 
 #ifdef __ASSEMBLY__
@@ -28,10 +30,14 @@
 #define PER_CPU(var, reg)						\
 	__percpu_mov_op %__percpu_seg:this_cpu_off, reg;		\
 	lea var(reg), reg
-#define PER_CPU_VAR(var)	%__percpu_seg:var
+/* Compatible with Position Independent Code */
+#define PER_CPU_VAR(var)		%__percpu_seg:(var)##__percpu_rel
+/* Rare absolute reference */
+#define PER_CPU_VAR_ABS(var)		%__percpu_seg:var
 #else /* ! SMP */
 #define PER_CPU(var, reg)	__percpu_mov_op $var, reg
-#define PER_CPU_VAR(var)	var
+#define PER_CPU_VAR(var)	(var)##__percpu_rel
+#define PER_CPU_VAR_ABS(var)	var
 #endif	/* SMP */
 
 #ifdef CONFIG_X86_64_SMP
@@ -209,27 +215,34 @@ do {									\
 	pfo_ret__;					\
 })
 
+/* Position Independent code uses relative addresses only */
+#ifdef CONFIG_X86_PIE
+#define __percpu_stable_arg __percpu_arg(a1)
+#else
+#define __percpu_stable_arg __percpu_arg(P1)
+#endif
+
 #define percpu_stable_op(op, var)			\
 ({							\
 	typeof(var) pfo_ret__;				\
 	switch (sizeof(var)) {				\
 	case 1:						\
-		asm(op "b "__percpu_arg(P1)",%0"	\
+		asm(op "b "__percpu_stable_arg ",%0"	\
 		    : "=q" (pfo_ret__)			\
 		    : "p" (&(var)));			\
 		break;					\
 	case 2:						\
-		asm(op "w "__percpu_arg(P1)",%0"	\
+		asm(op "w "__percpu_stable_arg ",%0"	\
 		    : "=r" (pfo_ret__)			\
 		    : "p" (&(var)));			\
 		break;					\
 	case 4:						\
-		asm(op "l "__percpu_arg(P1)",%0"	\
+		asm(op "l "__percpu_stable_arg ",%0"	\
 		    : "=r" (pfo_ret__)			\
 		    : "p" (&(var)));			\
 		break;					\
 	case 8:						\
-		asm(op "q "__percpu_arg(P1)",%0"	\
+		asm(op "q "__percpu_stable_arg ",%0"	\
 		    : "=r" (pfo_ret__)			\
 		    : "p" (&(var)));			\
 		break;					\
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 348cf4821240..0e9a87a34f76 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -487,7 +487,9 @@ void load_percpu_segment(int cpu)
 	loadsegment(fs, __KERNEL_PERCPU);
 #else
 	__loadsegment_simple(gs, 0);
-	wrmsrl(MSR_GS_BASE, (unsigned long)per_cpu(irq_stack_union.gs_base, cpu));
+	wrmsrl(MSR_GS_BASE,
+	       (unsigned long)per_cpu(irq_stack_union.gs_base, cpu) -
+	       (unsigned long)__per_cpu_start);
 #endif
 	load_stack_canary_segment();
 }
diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index 48652f3ec46a..87624e1fe22f 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -266,7 +266,11 @@ ENDPROC(start_cpu0)
 	GLOBAL(initial_code)
 	.quad	x86_64_start_kernel
 	GLOBAL(initial_gs)
+#ifdef CONFIG_X86_PIE
+	.quad	0
+#else
 	.quad	INIT_PER_CPU_VAR(irq_stack_union)
+#endif
 	GLOBAL(initial_stack)
 	/*
 	 * The SIZEOF_PTREGS gap is a convention which helps the in-kernel
diff --git a/arch/x86/kernel/setup_percpu.c b/arch/x86/kernel/setup_percpu.c
index ea554f812ee1..f7655979f19a 100644
--- a/arch/x86/kernel/setup_percpu.c
+++ b/arch/x86/kernel/setup_percpu.c
@@ -26,7 +26,7 @@
 DEFINE_PER_CPU_READ_MOSTLY(int, cpu_number);
 EXPORT_PER_CPU_SYMBOL(cpu_number);
 
-#ifdef CONFIG_X86_64
+#if defined(CONFIG_X86_64) && !defined(CONFIG_X86_PIE)
 #define BOOT_PERCPU_OFFSET ((unsigned long)__per_cpu_load)
 #else
 #define BOOT_PERCPU_OFFSET 0
diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S
index 1c43a2e839fa..4a5957900dcc 100644
--- a/arch/x86/kernel/vmlinux.lds.S
+++ b/arch/x86/kernel/vmlinux.lds.S
@@ -209,9 +209,14 @@ SECTIONS
 	/*
 	 * percpu offsets are zero-based on SMP.  PERCPU_VADDR() changes the
 	 * output PHDR, so the next output section - .init.text - should
-	 * start another segment - init.
+	 * start another segment - init. For Position Independent Code, the
+	 * per-cpu section cannot be zero-based because everything is relative.
 	 */
+#ifdef CONFIG_X86_PIE
+	PERCPU_SECTION(INTERNODE_CACHE_BYTES)
+#else
 	PERCPU_VADDR(INTERNODE_CACHE_BYTES, 0, :percpu)
+#endif
 	ASSERT(SIZEOF(.data..percpu) < CONFIG_PHYSICAL_START,
 	       "per-CPU data too large - increase CONFIG_PHYSICAL_START")
 #endif
@@ -387,7 +392,11 @@ SECTIONS
  * Per-cpu symbols which need to be offset from __per_cpu_load
  * for the boot processor.
  */
+#ifdef CONFIG_X86_PIE
+#define INIT_PER_CPU(x) init_per_cpu__##x = x
+#else
 #define INIT_PER_CPU(x) init_per_cpu__##x = x + __per_cpu_load
+#endif
 INIT_PER_CPU(gdt_page);
 INIT_PER_CPU(irq_stack_union);
 
@@ -397,7 +406,7 @@ INIT_PER_CPU(irq_stack_union);
 . = ASSERT((_end - _text <= KERNEL_IMAGE_SIZE),
 	   "kernel image bigger than KERNEL_IMAGE_SIZE");
 
-#ifdef CONFIG_SMP
+#if defined(CONFIG_SMP) && !defined(CONFIG_X86_PIE)
 . = ASSERT((irq_stack_union == 0),
            "irq_stack_union is not at start of per-cpu area");
 #endif
diff --git a/arch/x86/lib/cmpxchg16b_emu.S b/arch/x86/lib/cmpxchg16b_emu.S
index 9b330242e740..254950604ae4 100644
--- a/arch/x86/lib/cmpxchg16b_emu.S
+++ b/arch/x86/lib/cmpxchg16b_emu.S
@@ -33,13 +33,13 @@ ENTRY(this_cpu_cmpxchg16b_emu)
 	pushfq
 	cli
 
-	cmpq PER_CPU_VAR((%rsi)), %rax
+	cmpq PER_CPU_VAR_ABS((%rsi)), %rax
 	jne .Lnot_same
-	cmpq PER_CPU_VAR(8(%rsi)), %rdx
+	cmpq PER_CPU_VAR_ABS(8(%rsi)), %rdx
 	jne .Lnot_same
 
-	movq %rbx, PER_CPU_VAR((%rsi))
-	movq %rcx, PER_CPU_VAR(8(%rsi))
+	movq %rbx, PER_CPU_VAR_ABS((%rsi))
+	movq %rcx, PER_CPU_VAR_ABS(8(%rsi))
 
 	popfq
 	mov $1, %al
diff --git a/arch/x86/xen/xen-asm.S b/arch/x86/xen/xen-asm.S
index 8019edd0125c..a5d73d3218be 100644
--- a/arch/x86/xen/xen-asm.S
+++ b/arch/x86/xen/xen-asm.S
@@ -21,7 +21,7 @@
 ENTRY(xen_irq_enable_direct)
 	FRAME_BEGIN
 	/* Unmask events */
-	movb $0, PER_CPU_VAR(xen_vcpu_info) + XEN_vcpu_info_mask
+	movb $0, PER_CPU_VAR(xen_vcpu_info + XEN_vcpu_info_mask)
 
 	/*
 	 * Preempt here doesn't matter because that will deal with any
@@ -30,7 +30,7 @@ ENTRY(xen_irq_enable_direct)
 	 */
 
 	/* Test for pending */
-	testb $0xff, PER_CPU_VAR(xen_vcpu_info) + XEN_vcpu_info_pending
+	testb $0xff, PER_CPU_VAR(xen_vcpu_info + XEN_vcpu_info_pending)
 	jz 1f
 
 	call check_events
@@ -45,7 +45,7 @@ ENTRY(xen_irq_enable_direct)
  * non-zero.
  */
 ENTRY(xen_irq_disable_direct)
-	movb $1, PER_CPU_VAR(xen_vcpu_info) + XEN_vcpu_info_mask
+	movb $1, PER_CPU_VAR(xen_vcpu_info + XEN_vcpu_info_mask)
 	ret
 ENDPROC(xen_irq_disable_direct)
 
@@ -59,7 +59,7 @@ ENDPROC(xen_irq_disable_direct)
  * x86 use opposite senses (mask vs enable).
  */
 ENTRY(xen_save_fl_direct)
-	testb $0xff, PER_CPU_VAR(xen_vcpu_info) + XEN_vcpu_info_mask
+	testb $0xff, PER_CPU_VAR(xen_vcpu_info + XEN_vcpu_info_mask)
 	setz %ah
 	addb %ah, %ah
 	ret
@@ -80,7 +80,7 @@ ENTRY(xen_restore_fl_direct)
 #else
 	testb $X86_EFLAGS_IF>>8, %ah
 #endif
-	setz PER_CPU_VAR(xen_vcpu_info) + XEN_vcpu_info_mask
+	setz PER_CPU_VAR(xen_vcpu_info + XEN_vcpu_info_mask)
 	/*
 	 * Preempt here doesn't matter because that will deal with any
 	 * pending interrupts.  The pending check may end up being run
@@ -88,7 +88,7 @@ ENTRY(xen_restore_fl_direct)
 	 */
 
 	/* check for unmasked and pending */
-	cmpw $0x0001, PER_CPU_VAR(xen_vcpu_info) + XEN_vcpu_info_pending
+	cmpw $0x0001, PER_CPU_VAR(xen_vcpu_info + XEN_vcpu_info_pending)
 	jnz 1f
 	call check_events
 1:
diff --git a/init/Kconfig b/init/Kconfig
index 221cac95044f..acc9087546ac 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1365,7 +1365,7 @@ config KALLSYMS_ALL
 config KALLSYMS_ABSOLUTE_PERCPU
 	bool
 	depends on KALLSYMS
-	default X86_64 && SMP
+	default X86_64 && SMP && !X86_PIE
 
 config KALLSYMS_BASE_RELATIVE
 	bool
-- 
2.16.2.660.g709887971b-goog

[PATCH v2 15/27] compiler: Option to default to hidden symbols

[Thomas Garnier]

Provide an option to default visibility to hidden except for key
symbols. This option is disabled by default and will be used by x86_64
PIE support to remove errors between compilation units.

The default visibility is also enabled for external symbols that are
compared as they maybe equals (start/end of sections). In this case,
older versions of GCC will remove the comparison if the symbols are
hidden. This issue exists at least on gcc 4.9 and before.

Signed-off-by: Thomas Garnier <thgarnie@google.com>
---
 arch/x86/boot/boot.h                 |  2 +-
 arch/x86/include/asm/setup.h         |  2 +-
 arch/x86/kernel/cpu/microcode/core.c |  4 ++--
 drivers/base/firmware_class.c        |  4 ++--
 include/asm-generic/sections.h       |  6 ++++++
 include/linux/compiler.h             |  7 +++++++
 init/Kconfig                         |  7 +++++++
 kernel/kallsyms.c                    | 16 ++++++++--------
 kernel/trace/trace.h                 |  4 ++--
 lib/dynamic_debug.c                  |  4 ++--
 10 files changed, 38 insertions(+), 18 deletions(-)

diff --git a/arch/x86/boot/boot.h b/arch/x86/boot/boot.h
index ef5a9cc66fb8..d726c35bdd96 100644
--- a/arch/x86/boot/boot.h
+++ b/arch/x86/boot/boot.h
@@ -193,7 +193,7 @@ static inline bool memcmp_gs(const void *s1, addr_t s2, size_t len)
 }
 
 /* Heap -- available for dynamic lists. */
-extern char _end[];
+extern char _end[] __default_visibility;
 extern char *HEAP;
 extern char *heap_end;
 #define RESET_HEAP() ((void *)( HEAP = _end ))
diff --git a/arch/x86/include/asm/setup.h b/arch/x86/include/asm/setup.h
index 3108e297d87d..dfba64fe1c7e 100644
--- a/arch/x86/include/asm/setup.h
+++ b/arch/x86/include/asm/setup.h
@@ -70,7 +70,7 @@ static inline void x86_ce4100_early_setup(void) { }
  * This is set up by the setup-routine at boot-time
  */
 extern struct boot_params boot_params;
-extern char _text[];
+extern char _text[] __default_visibility;
 
 static inline bool kaslr_enabled(void)
 {
diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/microcode/core.c
index aa1b9a422f2b..ed5675db6e82 100644
--- a/arch/x86/kernel/cpu/microcode/core.c
+++ b/arch/x86/kernel/cpu/microcode/core.c
@@ -141,8 +141,8 @@ static bool __init check_loader_disabled_bsp(void)
 	return *res;
 }
 
-extern struct builtin_fw __start_builtin_fw[];
-extern struct builtin_fw __end_builtin_fw[];
+extern struct builtin_fw __start_builtin_fw[] __default_visibility;
+extern struct builtin_fw __end_builtin_fw[] __default_visibility;
 
 bool get_builtin_firmware(struct cpio_data *cd, const char *name)
 {
diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
index 7dd36ace6152..939a1952d0ab 100644
--- a/drivers/base/firmware_class.c
+++ b/drivers/base/firmware_class.c
@@ -136,8 +136,8 @@ static struct firmware_cache fw_cache;
 
 #ifdef CONFIG_FW_LOADER
 
-extern struct builtin_fw __start_builtin_fw[];
-extern struct builtin_fw __end_builtin_fw[];
+extern struct builtin_fw __start_builtin_fw[] __default_visibility;
+extern struct builtin_fw __end_builtin_fw[] __default_visibility;
 
 static void fw_copy_to_prealloc_buf(struct firmware *fw,
 				    void *buf, size_t size)
diff --git a/include/asm-generic/sections.h b/include/asm-generic/sections.h
index 849cd8eb5ca0..0a0e23405ddd 100644
--- a/include/asm-generic/sections.h
+++ b/include/asm-generic/sections.h
@@ -32,6 +32,9 @@
  *	__softirqentry_text_start, __softirqentry_text_end
  *	__start_opd, __end_opd
  */
+#ifdef CONFIG_DEFAULT_HIDDEN
+#pragma GCC visibility push(default)
+#endif
 extern char _text[], _stext[], _etext[];
 extern char _data[], _sdata[], _edata[];
 extern char __bss_start[], __bss_stop[];
@@ -49,6 +52,9 @@ extern char __start_once[], __end_once[];
 
 /* Start and end of .ctors section - used for constructor calls. */
 extern char __ctors_start[], __ctors_end[];
+#ifdef CONFIG_DEFAULT_HIDDEN
+#pragma GCC visibility pop
+#endif
 
 /* Start and end of .opd section - used for function descriptors. */
 extern char __start_opd[], __end_opd[];
diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index ab4711c63601..a9ac84e37af9 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -278,6 +278,13 @@ unsigned long read_word_at_a_time(const void *addr)
 	__u.__val;					\
 })
 
+#ifdef CONFIG_DEFAULT_HIDDEN
+#pragma GCC visibility push(hidden)
+#define __default_visibility  __attribute__((visibility ("default")))
+#else
+#define __default_visibility
+#endif
+
 #endif /* __KERNEL__ */
 
 #endif /* __ASSEMBLY__ */
diff --git a/init/Kconfig b/init/Kconfig
index acc9087546ac..c924babc6d47 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1667,6 +1667,13 @@ config PROFILING
 config TRACEPOINTS
 	bool
 
+#
+# Default to hidden visibility for all symbols.
+# Useful for Position Independent Code to reduce global references.
+#
+config DEFAULT_HIDDEN
+	bool
+
 source "arch/Kconfig"
 
 endmenu		# General setup
diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c
index a23e21ada81b..f4e58b7a6daf 100644
--- a/kernel/kallsyms.c
+++ b/kernel/kallsyms.c
@@ -29,24 +29,24 @@
  * These will be re-linked against their real values
  * during the second link stage.
  */
-extern const unsigned long kallsyms_addresses[] __weak;
-extern const int kallsyms_offsets[] __weak;
-extern const u8 kallsyms_names[] __weak;
+extern const unsigned long kallsyms_addresses[] __weak __default_visibility;
+extern const int kallsyms_offsets[] __weak __default_visibility;
+extern const u8 kallsyms_names[] __weak __default_visibility;
 
 /*
  * Tell the compiler that the count isn't in the small data section if the arch
  * has one (eg: FRV).
  */
 extern const unsigned long kallsyms_num_syms
-__attribute__((weak, section(".rodata")));
+__attribute__((weak, section(".rodata"))) __default_visibility;
 
 extern const unsigned long kallsyms_relative_base
-__attribute__((weak, section(".rodata")));
+__attribute__((weak, section(".rodata"))) __default_visibility;
 
-extern const u8 kallsyms_token_table[] __weak;
-extern const u16 kallsyms_token_index[] __weak;
+extern const u8 kallsyms_token_table[] __weak __default_visibility;
+extern const u16 kallsyms_token_index[] __weak __default_visibility;
 
-extern const unsigned long kallsyms_markers[] __weak;
+extern const unsigned long kallsyms_markers[] __weak __default_visibility;
 
 /*
  * Expand a compressed symbol data into the resulting uncompressed string,
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 2a6d0325a761..5aebb0dcecba 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -1741,8 +1741,8 @@ extern int trace_event_enable_disable(struct trace_event_file *file,
 				      int enable, int soft_disable);
 extern int tracing_alloc_snapshot(void);
 
-extern const char *__start___trace_bprintk_fmt[];
-extern const char *__stop___trace_bprintk_fmt[];
+extern const char *__start___trace_bprintk_fmt[] __default_visibility;
+extern const char *__stop___trace_bprintk_fmt[] __default_visibility;
 
 extern const char *__start___tracepoint_str[];
 extern const char *__stop___tracepoint_str[];
diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index c7c96bc7654a..40b752b53627 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -37,8 +37,8 @@
 #include <linux/device.h>
 #include <linux/netdevice.h>
 
-extern struct _ddebug __start___verbose[];
-extern struct _ddebug __stop___verbose[];
+extern struct _ddebug __start___verbose[] __default_visibility;
+extern struct _ddebug __stop___verbose[] __default_visibility;
 
 struct ddebug_table {
 	struct list_head link;
-- 
2.16.2.660.g709887971b-goog

[PATCH v2 16/27] compiler: Option to add PROVIDE_HIDDEN replacement for weak symbols

[Thomas Garnier]

Provide an option to have a PROVIDE_HIDDEN (linker script) entry for
each weak symbol. This option solve an error in x86_64 where the linker
optimizes pie generate code to be non-pie because --emit-relocs was used
instead of -pie (to reduce dynamic relocations).

Signed-off-by: Thomas Garnier <thgarnie@google.com>
---
 init/Kconfig            |  7 +++++++
 scripts/link-vmlinux.sh | 14 ++++++++++++++
 2 files changed, 21 insertions(+)

diff --git a/init/Kconfig b/init/Kconfig
index c924babc6d47..fe9f9ada4db0 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1927,6 +1927,13 @@ config ASN1
 	  inform it as to what tags are to be expected in a stream and what
 	  functions to call on what tags.
 
+config WEAK_PROVIDE_HIDDEN
+	bool
+	help
+	  Generate linker script PROVIDE_HIDDEN entries for all weak symbols. It
+	  allows to prevent non-pie code being replaced by the linker if the
+	  emit-relocs option is used instead of pie (useful for x86_64 pie).
+
 source "kernel/Kconfig.locks"
 
 config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
index 08ca08e9105c..c015f5142ecf 100755
--- a/scripts/link-vmlinux.sh
+++ b/scripts/link-vmlinux.sh
@@ -146,6 +146,17 @@ kallsyms()
 	${CC} ${aflags} -c -o ${2} ${afile}
 }
 
+gen_weak_provide_hidden()
+{
+        if [ -n "${CONFIG_WEAK_PROVIDE_HIDDEN}" ]; then
+                local pattern="s/^\s\+ w \(\w\+\)$/PROVIDE_HIDDEN(\1 = .);/gp"
+                echo -e "SECTIONS {\n. = _end;" > .tmp_vmlinux_hiddenld
+                ${NM} ${1} | sed -n "${pattern}" >> .tmp_vmlinux_hiddenld
+                echo "}" >> .tmp_vmlinux_hiddenld
+                LDFLAGS_vmlinux="${LDFLAGS_vmlinux} -T .tmp_vmlinux_hiddenld"
+        fi
+}
+
 # Create map file with all symbols from ${1}
 # See mksymap for additional details
 mksysmap()
@@ -230,6 +241,9 @@ modpost_link vmlinux.o
 # modpost vmlinux.o to check for section mismatches
 ${MAKE} -f "${srctree}/scripts/Makefile.modpost" vmlinux.o
 
+# Generate weak linker script
+gen_weak_provide_hidden vmlinux.o
+
 kallsymso=""
 kallsyms_vmlinux=""
 if [ -n "${CONFIG_KALLSYMS}" ]; then
-- 
2.16.2.660.g709887971b-goog

[PATCH v2 17/27] x86/relocs: Handle PIE relocations

[Thomas Garnier]

Change the relocation tool to correctly handle relocations generated by
-fPIE option:

 - Add relocation for each entry of the .got section given the linker does not
   generate R_X86_64_GLOB_DAT on a simple link.
 - Ignore R_X86_64_GOTPCREL.

Signed-off-by: Thomas Garnier <thgarnie@google.com>
---
 arch/x86/tools/relocs.c | 93 ++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 92 insertions(+), 1 deletion(-)

diff --git a/arch/x86/tools/relocs.c b/arch/x86/tools/relocs.c
index 220e97841e49..a35cc337f883 100644
--- a/arch/x86/tools/relocs.c
+++ b/arch/x86/tools/relocs.c
@@ -32,6 +32,7 @@ struct section {
 	Elf_Sym        *symtab;
 	Elf_Rel        *reltab;
 	char           *strtab;
+	Elf_Addr       *got;
 };
 static struct section *secs;
 
@@ -293,6 +294,35 @@ static Elf_Sym *sym_lookup(const char *symname)
 	return 0;
 }
 
+static Elf_Sym *sym_lookup_addr(Elf_Addr addr, const char **name)
+{
+	int i;
+	for (i = 0; i < ehdr.e_shnum; i++) {
+		struct section *sec = &secs[i];
+		long nsyms;
+		Elf_Sym *symtab;
+		Elf_Sym *sym;
+
+		if (sec->shdr.sh_type != SHT_SYMTAB)
+			continue;
+
+		nsyms = sec->shdr.sh_size/sizeof(Elf_Sym);
+		symtab = sec->symtab;
+
+		for (sym = symtab; --nsyms >= 0; sym++) {
+			if (sym->st_value == addr) {
+				if (name) {
+					*name = sym_name(sec->link->strtab,
+							 sym);
+				}
+				return sym;
+			}
+		}
+	}
+	return 0;
+}
+
+
 #if BYTE_ORDER == LITTLE_ENDIAN
 #define le16_to_cpu(val) (val)
 #define le32_to_cpu(val) (val)
@@ -513,6 +543,33 @@ static void read_relocs(FILE *fp)
 	}
 }
 
+static void read_got(FILE *fp)
+{
+	int i;
+	for (i = 0; i < ehdr.e_shnum; i++) {
+		struct section *sec = &secs[i];
+		sec->got = NULL;
+		if (sec->shdr.sh_type != SHT_PROGBITS ||
+		    strcmp(sec_name(i), ".got")) {
+			continue;
+		}
+		sec->got = malloc(sec->shdr.sh_size);
+		if (!sec->got) {
+			die("malloc of %d bytes for got failed\n",
+				sec->shdr.sh_size);
+		}
+		if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) {
+			die("Seek to %d failed: %s\n",
+				sec->shdr.sh_offset, strerror(errno));
+		}
+		if (fread(sec->got, 1, sec->shdr.sh_size, fp)
+		    != sec->shdr.sh_size) {
+			die("Cannot read got: %s\n",
+				strerror(errno));
+		}
+	}
+}
+
 
 static void print_absolute_symbols(void)
 {
@@ -643,6 +700,32 @@ static void add_reloc(struct relocs *r, uint32_t offset)
 	r->offset[r->count++] = offset;
 }
 
+/*
+ * The linker does not generate relocations for the GOT for the kernel.
+ * If a GOT is found, simulate the relocations that should have been included.
+ */
+static void walk_got_table(int (*process)(struct section *sec, Elf_Rel *rel,
+					  Elf_Sym *sym, const char *symname),
+			   struct section *sec)
+{
+	int i;
+	Elf_Addr entry;
+	Elf_Sym *sym;
+	const char *symname;
+	Elf_Rel rel;
+
+	for (i = 0; i < sec->shdr.sh_size/sizeof(Elf_Addr); i++) {
+		entry = sec->got[i];
+		sym = sym_lookup_addr(entry, &symname);
+		if (!sym)
+			die("Could not found got symbol for entry %d\n", i);
+		rel.r_offset = sec->shdr.sh_addr + i * sizeof(Elf_Addr);
+		rel.r_info = ELF_BITS == 64 ? R_X86_64_GLOB_DAT
+			     : R_386_GLOB_DAT;
+		process(sec, &rel, sym, symname);
+	}
+}
+
 static void walk_relocs(int (*process)(struct section *sec, Elf_Rel *rel,
 			Elf_Sym *sym, const char *symname))
 {
@@ -656,6 +739,8 @@ static void walk_relocs(int (*process)(struct section *sec, Elf_Rel *rel,
 		struct section *sec = &secs[i];
 
 		if (sec->shdr.sh_type != SHT_REL_TYPE) {
+			if (sec->got)
+				walk_got_table(process, sec);
 			continue;
 		}
 		sec_symtab  = sec->link;
@@ -765,6 +850,7 @@ static int do_reloc64(struct section *sec, Elf_Rel *rel, ElfW(Sym) *sym,
 		offset += per_cpu_load_addr;
 
 	switch (r_type) {
+	case R_X86_64_GOTPCREL:
 	case R_X86_64_NONE:
 		/* NONE can be ignored. */
 		break;
@@ -809,7 +895,7 @@ static int do_reloc64(struct section *sec, Elf_Rel *rel, ElfW(Sym) *sym,
 		 * the relocations are processed.
 		 * Make sure that the offset will fit.
 		 */
-		if ((int32_t)offset != (int64_t)offset)
+		if (r_type != R_X86_64_64 && (int32_t)offset != (int64_t)offset)
 			die("Relocation offset doesn't fit in 32 bits\n");
 
 		if (r_type == R_X86_64_64)
@@ -818,6 +904,10 @@ static int do_reloc64(struct section *sec, Elf_Rel *rel, ElfW(Sym) *sym,
 			add_reloc(&relocs32, offset);
 		break;
 
+	case R_X86_64_GLOB_DAT:
+		add_reloc(&relocs64, offset);
+		break;
+
 	default:
 		die("Unsupported relocation type: %s (%d)\n",
 		    rel_type(r_type), r_type);
@@ -1087,6 +1177,7 @@ void process(FILE *fp, int use_real_mode, int as_text,
 	read_strtabs(fp);
 	read_symtabs(fp);
 	read_relocs(fp);
+	read_got(fp);
 	if (ELF_BITS == 64)
 		percpu_init();
 	if (show_absolute_syms) {
-- 
2.16.2.660.g709887971b-goog

[PATCH v2 18/27] xen: Adapt assembly for PIE support

[Thomas Garnier]

Change the assembly code to use the new _ASM_MOVABS macro which get a
symbol reference while being PIE compatible. Adapt the relocation tool
to ignore 32-bit Xen code.

Position Independent Executable (PIE) support will allow to extended the
KASLR randomization range below the -2G memory limit.

Signed-off-by: Thomas Garnier <thgarnie@google.com>
---
 arch/x86/tools/relocs.c | 16 +++++++++++++++-
 arch/x86/xen/xen-head.S | 11 ++++++-----
 arch/x86/xen/xen-pvh.S  | 13 +++++++++----
 3 files changed, 30 insertions(+), 10 deletions(-)

diff --git a/arch/x86/tools/relocs.c b/arch/x86/tools/relocs.c
index a35cc337f883..29283ad3950f 100644
--- a/arch/x86/tools/relocs.c
+++ b/arch/x86/tools/relocs.c
@@ -832,6 +832,16 @@ static int is_percpu_sym(ElfW(Sym) *sym, const char *symname)
 		strncmp(symname, "init_per_cpu_", 13);
 }
 
+/*
+ * Check if the 32-bit relocation is within the xenpvh 32-bit code.
+ * If so, ignores it.
+ */
+static int is_in_xenpvh_assembly(ElfW(Addr) offset)
+{
+	ElfW(Sym) *sym = sym_lookup("pvh_start_xen");
+	return sym && (offset >= sym->st_value) &&
+		(offset < (sym->st_value + sym->st_size));
+}
 
 static int do_reloc64(struct section *sec, Elf_Rel *rel, ElfW(Sym) *sym,
 		      const char *symname)
@@ -895,8 +905,12 @@ static int do_reloc64(struct section *sec, Elf_Rel *rel, ElfW(Sym) *sym,
 		 * the relocations are processed.
 		 * Make sure that the offset will fit.
 		 */
-		if (r_type != R_X86_64_64 && (int32_t)offset != (int64_t)offset)
+		if (r_type != R_X86_64_64 &&
+		    (int32_t)offset != (int64_t)offset) {
+			if (is_in_xenpvh_assembly(offset))
+				break;
 			die("Relocation offset doesn't fit in 32 bits\n");
+		}
 
 		if (r_type == R_X86_64_64)
 			add_reloc(&relocs64, offset);
diff --git a/arch/x86/xen/xen-head.S b/arch/x86/xen/xen-head.S
index 96f26e026783..210568e63c84 100644
--- a/arch/x86/xen/xen-head.S
+++ b/arch/x86/xen/xen-head.S
@@ -28,14 +28,15 @@ ENTRY(startup_xen)
 
 	/* Clear .bss */
 	xor %eax,%eax
-	mov $__bss_start, %_ASM_DI
-	mov $__bss_stop, %_ASM_CX
+	_ASM_MOVABS $__bss_start, %_ASM_DI
+	_ASM_MOVABS $__bss_stop, %_ASM_CX
 	sub %_ASM_DI, %_ASM_CX
 	shr $__ASM_SEL(2, 3), %_ASM_CX
 	rep __ASM_SIZE(stos)
 
-	mov %_ASM_SI, xen_start_info
-	mov $init_thread_union+THREAD_SIZE, %_ASM_SP
+	_ASM_MOVABS $xen_start_info, %_ASM_AX
+	_ASM_MOV %_ASM_SI, (%_ASM_AX)
+	_ASM_MOVABS $init_thread_union+THREAD_SIZE, %_ASM_SP
 
 #ifdef CONFIG_X86_64
 	/* Set up %gs.
@@ -46,7 +47,7 @@ ENTRY(startup_xen)
 	 * init data section till per cpu areas are set up.
 	 */
 	movl	$MSR_GS_BASE,%ecx
-	movq	$INIT_PER_CPU_VAR(irq_stack_union),%rax
+	movabsq	$INIT_PER_CPU_VAR(irq_stack_union),%rax
 	cdq
 	wrmsr
 #endif
diff --git a/arch/x86/xen/xen-pvh.S b/arch/x86/xen/xen-pvh.S
index e1a5fbeae08d..43e234c7c2de 100644
--- a/arch/x86/xen/xen-pvh.S
+++ b/arch/x86/xen/xen-pvh.S
@@ -101,8 +101,8 @@ ENTRY(pvh_start_xen)
 	call xen_prepare_pvh
 
 	/* startup_64 expects boot_params in %rsi. */
-	mov $_pa(pvh_bootparams), %rsi
-	mov $_pa(startup_64), %rax
+	movabs $_pa(pvh_bootparams), %rsi
+	movabs $_pa(startup_64), %rax
 	jmp *%rax
 
 #else /* CONFIG_X86_64 */
@@ -137,10 +137,15 @@ END(pvh_start_xen)
 
 	.section ".init.data","aw"
 	.balign 8
+	/*
+	 * Use a quad for _pa(gdt_start) because PIE does not understand a
+	 * long is enough. The resulting value will still be in the lower long
+	 * part.
+	 */
 gdt:
 	.word gdt_end - gdt_start
-	.long _pa(gdt_start)
-	.word 0
+	.quad _pa(gdt_start)
+	.balign 8
 gdt_start:
 	.quad 0x0000000000000000            /* NULL descriptor */
 	.quad 0x0000000000000000            /* reserved */
-- 
2.16.2.660.g709887971b-goog

[PATCH v2 19/27] kvm: Adapt assembly for PIE support

[Thomas Garnier]

Change the assembly code to use only relative references of symbols for the
kernel to be PIE compatible. The new __ASM_MOVABS macro is used to
get the address of a symbol on both 32 and 64-bit with PIE support.

Position Independent Executable (PIE) support will allow to extended the
KASLR randomization range below the -2G memory limit.

Signed-off-by: Thomas Garnier <thgarnie@google.com>
---
 arch/x86/include/asm/kvm_host.h | 6 ++++--
 arch/x86/kernel/kvm.c           | 6 ++++--
 arch/x86/kvm/svm.c              | 4 ++--
 3 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index b605a5b6a30c..7bd6ba79e778 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1380,9 +1380,11 @@ asmlinkage void kvm_spurious_fault(void);
 	".pushsection .fixup, \"ax\" \n" \
 	"667: \n\t" \
 	cleanup_insn "\n\t"		      \
-	"cmpb $0, kvm_rebooting \n\t"	      \
+	"cmpb $0, kvm_rebooting" __ASM_SEL(,(%%rip)) " \n\t" \
 	"jne 668b \n\t"      		      \
-	__ASM_SIZE(push) " $666b \n\t"	      \
+	__ASM_SIZE(push) "%%" _ASM_AX " \n\t"		\
+	_ASM_MOVABS " $666b, %%" _ASM_AX "\n\t"	\
+	"xchg %%" _ASM_AX ", (%%" _ASM_SP ") \n\t"	\
 	"call kvm_spurious_fault \n\t"	      \
 	".popsection \n\t" \
 	_ASM_EXTABLE(666b, 667b)
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index bc1a27280c4b..5e4dd958ea95 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -711,8 +711,10 @@ asm(
 ".global __raw_callee_save___kvm_vcpu_is_preempted;"
 ".type __raw_callee_save___kvm_vcpu_is_preempted, @function;"
 "__raw_callee_save___kvm_vcpu_is_preempted:"
-"movq	__per_cpu_offset(,%rdi,8), %rax;"
-"cmpb	$0, " __stringify(KVM_STEAL_TIME_preempted) "+steal_time(%rax);"
+"leaq	__per_cpu_offset(%rip), %rax;"
+"movq	(%rax,%rdi,8), %rax;"
+"addq	" __stringify(KVM_STEAL_TIME_preempted) "+steal_time(%rip), %rax;"
+"cmpb	$0, (%rax);"
 "setne	%al;"
 "ret;"
 ".popsection");
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index be9c839e2c89..6835a2ce02e5 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -626,12 +626,12 @@ static u32 svm_msrpm_offset(u32 msr)
 
 static inline void clgi(void)
 {
-	asm volatile (__ex(SVM_CLGI));
+	asm volatile (__ex(SVM_CLGI) : :);
 }
 
 static inline void stgi(void)
 {
-	asm volatile (__ex(SVM_STGI));
+	asm volatile (__ex(SVM_STGI) : :);
 }
 
 static inline void invlpga(unsigned long addr, u32 asid)
-- 
2.16.2.660.g709887971b-goog

[PATCH v2 20/27] x86: Support global stack cookie

[Thomas Garnier]

Add an off-by-default configuration option to use a global stack cookie
instead of the default TLS. This configuration option will only be used
with PIE binaries.

For kernel stack cookie, the compiler uses the mcmodel=kernel to switch
between the fs segment to gs segment. A PIE binary does not use
mcmodel=kernel because it can be relocated anywhere, therefore the
compiler will default to the fs segment register. This is fixed on the
latest version of gcc.

If the segment selector is available, it will be automatically added. If
the automatic configuration was selected, a warning is written and the
global variable stack cookie is used. If a specific stack mode was
selected (regular or strong) and the compiler does not support selecting
the segment register, an error is emitted.

Signed-off-by: Thomas Garnier <thgarnie@google.com>
---
 arch/x86/Kconfig                      | 12 ++++++++++++
 arch/x86/Makefile                     |  9 +++++++++
 arch/x86/entry/entry_32.S             |  3 ++-
 arch/x86/entry/entry_64.S             |  3 ++-
 arch/x86/include/asm/processor.h      |  3 ++-
 arch/x86/include/asm/stackprotector.h | 19 ++++++++++++++-----
 arch/x86/kernel/asm-offsets.c         |  3 ++-
 arch/x86/kernel/asm-offsets_32.c      |  3 ++-
 arch/x86/kernel/asm-offsets_64.c      |  3 ++-
 arch/x86/kernel/cpu/common.c          |  3 ++-
 arch/x86/kernel/head_32.S             |  3 ++-
 arch/x86/kernel/process.c             |  5 +++++
 12 files changed, 56 insertions(+), 13 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index a0a777ce4c7c..0cb1ae187c3e 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -2236,6 +2236,18 @@ config RANDOMIZE_MEMORY_PHYSICAL_PADDING
 
 	   If unsure, leave at the default value.
 
+config X86_GLOBAL_STACKPROTECTOR
+	bool "Stack cookie using a global variable"
+	depends on CC_STACKPROTECTOR_AUTO
+	default n
+	---help---
+	   This option turns on the "stack-protector" GCC feature using a global
+	   variable instead of a segment register. It is useful when the
+	   compiler does not support custom segment registers when building a
+	   position independent (PIE) binary.
+
+	   If unsure, say N
+
 config HOTPLUG_CPU
 	bool "Support for hot-pluggable CPUs"
 	depends on SMP
diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index 498c1b812300..16dafc551f3b 100644
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -142,6 +142,15 @@ else
         KBUILD_CFLAGS += $(call cc-option,-funit-at-a-time)
 endif
 
+ifdef CONFIG_X86_GLOBAL_STACKPROTECTOR
+        ifeq ($(call cc-option, -mstack-protector-guard=global),)
+                $(error Cannot use CONFIG_X86_GLOBAL_STACKPROTECTOR: \
+                        -mstack-protector-guard=global not supported \
+                        by compiler)
+        endif
+        KBUILD_CFLAGS += -mstack-protector-guard=global
+endif
+
 ifdef CONFIG_X86_X32
 	x32_ld_ok := $(call try-run,\
 			/bin/echo -e '1: .quad 1b' | \
diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S
index bef8e2b202a8..b7d5bc710ae7 100644
--- a/arch/x86/entry/entry_32.S
+++ b/arch/x86/entry/entry_32.S
@@ -239,7 +239,8 @@ ENTRY(__switch_to_asm)
 	movl	%esp, TASK_threadsp(%eax)
 	movl	TASK_threadsp(%edx), %esp
 
-#ifdef CONFIG_CC_STACKPROTECTOR
+#if defined(CONFIG_CC_STACKPROTECTOR) && \
+	!defined(CONFIG_X86_GLOBAL_STACKPROTECTOR)
 	movl	TASK_stack_canary(%edx), %ebx
 	movl	%ebx, PER_CPU_VAR(stack_canary)+stack_canary_offset
 #endif
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index d34794368e20..fbf2b63b4e78 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -356,7 +356,8 @@ ENTRY(__switch_to_asm)
 	movq	%rsp, TASK_threadsp(%rdi)
 	movq	TASK_threadsp(%rsi), %rsp
 
-#ifdef CONFIG_CC_STACKPROTECTOR
+#if defined(CONFIG_CC_STACKPROTECTOR) && \
+	!defined(CONFIG_X86_GLOBAL_STACKPROTECTOR)
 	movq	TASK_stack_canary(%rsi), %rbx
 	movq	%rbx, PER_CPU_VAR(irq_stack_union + stack_canary_offset)
 #endif
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 1b9488b1018a..f11284481597 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -411,7 +411,8 @@ DECLARE_PER_CPU(char *, irq_stack_ptr);
 DECLARE_PER_CPU(unsigned int, irq_count);
 extern asmlinkage void ignore_sysret(void);
 #else	/* X86_64 */
-#ifdef CONFIG_CC_STACKPROTECTOR
+#if defined(CONFIG_CC_STACKPROTECTOR) && \
+	!defined(CONFIG_X86_GLOBAL_STACKPROTECTOR)
 /*
  * Make sure stack canary segment base is cached-aligned:
  *   "For Intel Atom processors, avoid non zero segment base address
diff --git a/arch/x86/include/asm/stackprotector.h b/arch/x86/include/asm/stackprotector.h
index 371b3a4af000..5063f57d99f5 100644
--- a/arch/x86/include/asm/stackprotector.h
+++ b/arch/x86/include/asm/stackprotector.h
@@ -52,6 +52,10 @@
 #define GDT_STACK_CANARY_INIT						\
 	[GDT_ENTRY_STACK_CANARY] = GDT_ENTRY_INIT(0x4090, 0, 0x18),
 
+#ifdef CONFIG_X86_GLOBAL_STACKPROTECTOR
+extern unsigned long __stack_chk_guard;
+#endif
+
 /*
  * Initialize the stackprotector canary value.
  *
@@ -63,7 +67,7 @@ static __always_inline void boot_init_stack_canary(void)
 	u64 canary;
 	u64 tsc;
 
-#ifdef CONFIG_X86_64
+#if defined(CONFIG_X86_64) && !defined(CONFIG_X86_GLOBAL_STACKPROTECTOR)
 	BUILD_BUG_ON(offsetof(union irq_stack_union, stack_canary) != 40);
 #endif
 	/*
@@ -77,17 +81,22 @@ static __always_inline void boot_init_stack_canary(void)
 	canary += tsc + (tsc << 32UL);
 	canary &= CANARY_MASK;
 
+#ifdef CONFIG_X86_GLOBAL_STACKPROTECTOR
+	if (__stack_chk_guard == 0)
+		__stack_chk_guard = canary ?: 1;
+#else /* !CONFIG_X86_GLOBAL_STACKPROTECTOR */
 	current->stack_canary = canary;
 #ifdef CONFIG_X86_64
 	this_cpu_write(irq_stack_union.stack_canary, canary);
-#else
+#else /* CONFIG_X86_32 */
 	this_cpu_write(stack_canary.canary, canary);
 #endif
+#endif
 }
 
 static inline void setup_stack_canary_segment(int cpu)
 {
-#ifdef CONFIG_X86_32
+#if defined(CONFIG_X86_32) && !defined(CONFIG_X86_GLOBAL_STACKPROTECTOR)
 	unsigned long canary = (unsigned long)&per_cpu(stack_canary, cpu);
 	struct desc_struct *gdt_table = get_cpu_gdt_rw(cpu);
 	struct desc_struct desc;
@@ -100,7 +109,7 @@ static inline void setup_stack_canary_segment(int cpu)
 
 static inline void load_stack_canary_segment(void)
 {
-#ifdef CONFIG_X86_32
+#if defined(CONFIG_X86_32) && !defined(CONFIG_X86_GLOBAL_STACKPROTECTOR)
 	asm("mov %0, %%gs" : : "r" (__KERNEL_STACK_CANARY) : "memory");
 #endif
 }
@@ -116,7 +125,7 @@ static inline void setup_stack_canary_segment(int cpu)
 
 static inline void load_stack_canary_segment(void)
 {
-#ifdef CONFIG_X86_32
+#if defined(CONFIG_X86_32) && !defined(CONFIG_X86_GLOBAL_STACKPROTECTOR)
 	asm volatile ("mov %0, %%gs" : : "r" (0));
 #endif
 }
diff --git a/arch/x86/kernel/asm-offsets.c b/arch/x86/kernel/asm-offsets.c
index 76417a9aab73..4c9e1b667bda 100644
--- a/arch/x86/kernel/asm-offsets.c
+++ b/arch/x86/kernel/asm-offsets.c
@@ -32,7 +32,8 @@
 void common(void) {
 	BLANK();
 	OFFSET(TASK_threadsp, task_struct, thread.sp);
-#ifdef CONFIG_CC_STACKPROTECTOR
+#if defined(CONFIG_CC_STACKPROTECTOR) && \
+	!defined(CONFIG_X86_GLOBAL_STACKPROTECTOR)
 	OFFSET(TASK_stack_canary, task_struct, stack_canary);
 #endif
 
diff --git a/arch/x86/kernel/asm-offsets_32.c b/arch/x86/kernel/asm-offsets_32.c
index f91ba53e06c8..cf8ef55a8b82 100644
--- a/arch/x86/kernel/asm-offsets_32.c
+++ b/arch/x86/kernel/asm-offsets_32.c
@@ -50,7 +50,8 @@ void foo(void)
 	DEFINE(TSS_sysenter_sp0, offsetof(struct cpu_entry_area, tss.x86_tss.sp0) -
 	       offsetofend(struct cpu_entry_area, entry_stack_page.stack));
 
-#ifdef CONFIG_CC_STACKPROTECTOR
+#if defined(CONFIG_CC_STACKPROTECTOR) && \
+	!defined(CONFIG_X86_GLOBAL_STACKPROTECTOR)
 	BLANK();
 	OFFSET(stack_canary_offset, stack_canary, canary);
 #endif
diff --git a/arch/x86/kernel/asm-offsets_64.c b/arch/x86/kernel/asm-offsets_64.c
index bf51e51d808d..a3c7e14f6434 100644
--- a/arch/x86/kernel/asm-offsets_64.c
+++ b/arch/x86/kernel/asm-offsets_64.c
@@ -69,7 +69,8 @@ int main(void)
 	OFFSET(TSS_sp1, tss_struct, x86_tss.sp1);
 	BLANK();
 
-#ifdef CONFIG_CC_STACKPROTECTOR
+#if defined(CONFIG_CC_STACKPROTECTOR) && \
+	!defined(CONFIG_X86_GLOBAL_STACKPROTECTOR)
 	DEFINE(stack_canary_offset, offsetof(union irq_stack_union, stack_canary));
 	BLANK();
 #endif
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 0e9a87a34f76..aa63274115af 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1509,7 +1509,8 @@ DEFINE_PER_CPU(unsigned long, cpu_current_top_of_stack) =
 	(unsigned long)&init_thread_union + THREAD_SIZE;
 EXPORT_PER_CPU_SYMBOL(cpu_current_top_of_stack);
 
-#ifdef CONFIG_CC_STACKPROTECTOR
+#if defined(CONFIG_CC_STACKPROTECTOR) && \
+	!defined(CONFIG_X86_GLOBAL_STACKPROTECTOR)
 DEFINE_PER_CPU_ALIGNED(struct stack_canary, stack_canary);
 #endif
 
diff --git a/arch/x86/kernel/head_32.S b/arch/x86/kernel/head_32.S
index b59e4fb40fd9..0e849242de91 100644
--- a/arch/x86/kernel/head_32.S
+++ b/arch/x86/kernel/head_32.S
@@ -375,7 +375,8 @@ ENDPROC(startup_32_smp)
  */
 __INIT
 setup_once:
-#ifdef CONFIG_CC_STACKPROTECTOR
+#if defined(CONFIG_CC_STACKPROTECTOR) && \
+	!defined(CONFIG_X86_GLOBAL_STACKPROTECTOR)
 	/*
 	 * Configure the stack canary. The linker can't handle this by
 	 * relocation.  Manually set base address in stack canary
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 03408b942adb..ebe21d258a82 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -86,6 +86,11 @@ EXPORT_PER_CPU_SYMBOL(cpu_tss_rw);
 DEFINE_PER_CPU(bool, __tss_limit_invalid);
 EXPORT_PER_CPU_SYMBOL_GPL(__tss_limit_invalid);
 
+#ifdef CONFIG_X86_GLOBAL_STACKPROTECTOR
+unsigned long __stack_chk_guard __read_mostly;
+EXPORT_SYMBOL(__stack_chk_guard);
+#endif
+
 /*
  * this gets called so that we can store lazy state into memory and copy the
  * current task into the new thread.
-- 
2.16.2.660.g709887971b-goog

[PATCH v2 21/27] x86/ftrace: Adapt function tracing for PIE support

[Thomas Garnier]

When using -fPIE/PIC with function tracing, the compiler generates a
call through the GOT (call *__fentry__@GOTPCREL). This instruction
takes 6 bytes instead of 5 on the usual relative call.

If PIE is enabled, replace the 6th byte of the GOT call by a 1-byte nop
so ftrace can handle the previous 5-bytes as before.

Position Independent Executable (PIE) support will allow to extended the
KASLR randomization range below the -2G memory limit.

Signed-off-by: Thomas Garnier <thgarnie@google.com>
---
 arch/x86/include/asm/ftrace.h   |  6 +++--
 arch/x86/include/asm/sections.h |  4 ++++
 arch/x86/kernel/ftrace.c        | 42 +++++++++++++++++++++++++++++++--
 3 files changed, 48 insertions(+), 4 deletions(-)

diff --git a/arch/x86/include/asm/ftrace.h b/arch/x86/include/asm/ftrace.h
index 09ad88572746..61fa02d81b95 100644
--- a/arch/x86/include/asm/ftrace.h
+++ b/arch/x86/include/asm/ftrace.h
@@ -25,9 +25,11 @@ extern void __fentry__(void);
 static inline unsigned long ftrace_call_adjust(unsigned long addr)
 {
 	/*
-	 * addr is the address of the mcount call instruction.
-	 * recordmcount does the necessary offset calculation.
+	 * addr is the address of the mcount call instruction. PIE has always a
+	 * byte added to the start of the function.
 	 */
+	if (IS_ENABLED(CONFIG_X86_PIE))
+		addr -= 1;
 	return addr;
 }
 
diff --git a/arch/x86/include/asm/sections.h b/arch/x86/include/asm/sections.h
index d6baf23782bc..cad292f62eed 100644
--- a/arch/x86/include/asm/sections.h
+++ b/arch/x86/include/asm/sections.h
@@ -12,4 +12,8 @@ extern struct exception_table_entry __stop___ex_table[];
 extern char __end_rodata_hpage_align[];
 #endif
 
+#if defined(CONFIG_X86_PIE)
+extern char __start_got[], __end_got[];
+#endif
+
 #endif	/* _ASM_X86_SECTIONS_H */
diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index 01ebcb6f263e..21bde498f1a9 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -102,7 +102,7 @@ static const unsigned char *ftrace_nop_replace(void)
 
 static int
 ftrace_modify_code_direct(unsigned long ip, unsigned const char *old_code,
-		   unsigned const char *new_code)
+			  unsigned const char *new_code)
 {
 	unsigned char replaced[MCOUNT_INSN_SIZE];
 
@@ -135,6 +135,44 @@ ftrace_modify_code_direct(unsigned long ip, unsigned const char *old_code,
 	return 0;
 }
 
+/* Bytes before call GOT offset */
+const unsigned char got_call_preinsn[] = { 0xff, 0x15 };
+
+static int
+ftrace_modify_initial_code(unsigned long ip, unsigned const char *old_code,
+			   unsigned const char *new_code)
+{
+	unsigned char replaced[MCOUNT_INSN_SIZE + 1];
+
+	ftrace_expected = old_code;
+
+	/*
+	 * If PIE is not enabled or no GOT call was found, default to the
+	 * original approach to code modification.
+	 */
+	if (!IS_ENABLED(CONFIG_X86_PIE)
+	    || probe_kernel_read(replaced, (void *)ip, sizeof(replaced))
+	    || memcmp(replaced, got_call_preinsn, sizeof(got_call_preinsn)))
+		return ftrace_modify_code_direct(ip, old_code, new_code);
+
+	/*
+	 * Build a nop slide with a 5-byte nop and 1-byte nop to keep the ftrace
+	 * hooking algorithm working with the expected 5 bytes instruction.
+	 */
+	memcpy(replaced, new_code, MCOUNT_INSN_SIZE);
+	replaced[MCOUNT_INSN_SIZE] = ideal_nops[1][0];
+
+	ip = text_ip_addr(ip);
+
+	if (probe_kernel_write((void *)ip, replaced, sizeof(replaced)))
+		return -EPERM;
+
+	sync_core();
+
+	return 0;
+
+}
+
 int ftrace_make_nop(struct module *mod,
 		    struct dyn_ftrace *rec, unsigned long addr)
 {
@@ -153,7 +191,7 @@ int ftrace_make_nop(struct module *mod,
 	 * just modify the code directly.
 	 */
 	if (addr == MCOUNT_ADDR)
-		return ftrace_modify_code_direct(rec->ip, old, new);
+		return ftrace_modify_initial_code(rec->ip, old, new);
 
 	ftrace_expected = NULL;
 
-- 
2.16.2.660.g709887971b-goog

Re: [PATCH v2 21/27] x86/ftrace: Adapt function tracing for PIE support

[Peter Zijlstra]

On Tue, Mar 13, 2018 at 01:59:39PM -0700, Thomas Garnier wrote:
> +	/*
> +	 * If PIE is not enabled or no GOT call was found, default to the
> +	 * original approach to code modification.
> +	 */
> +	if (!IS_ENABLED(CONFIG_X86_PIE)
> +	    || probe_kernel_read(replaced, (void *)ip, sizeof(replaced))
> +	    || memcmp(replaced, got_call_preinsn, sizeof(got_call_preinsn)))
> +		return ftrace_modify_code_direct(ip, old_code, new_code);

The predominant kernel style is to place the operators at the end of the
previous line, not first on the new line.

[PATCH v2 22/27] x86/modules: Add option to start module section after kernel

[Thomas Garnier]

Add an option so the module section is just after the mapped kernel. It
will ensure position independent modules are always at the right
distance from the kernel and do not require mcmodule=large. It also
optimize the available size for modules by getting rid of the empty
space on kernel randomization range.

Signed-off-by: Thomas Garnier <thgarnie@google.com>
---
 Documentation/x86/x86_64/mm.txt         | 3 +++
 arch/x86/Kconfig                        | 4 ++++
 arch/x86/include/asm/pgtable_64_types.h | 6 ++++++
 arch/x86/kernel/head64.c                | 5 ++++-
 arch/x86/mm/dump_pagetables.c           | 3 ++-
 5 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/Documentation/x86/x86_64/mm.txt b/Documentation/x86/x86_64/mm.txt
index ea91cb61a602..ec1dfe4c3cfe 100644
--- a/Documentation/x86/x86_64/mm.txt
+++ b/Documentation/x86/x86_64/mm.txt
@@ -77,3 +77,6 @@ Their order is preserved but their base will be offset early at boot time.
 Be very careful vs. KASLR when changing anything here. The KASLR address
 range must not overlap with anything except the KASAN shadow area, which is
 correct as KASAN disables KASLR.
+
+If CONFIG_DYNAMIC_MODULE_BASE is enabled, the module section follows the end of
+the mapped kernel.
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 0cb1ae187c3e..df4134fd3247 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -2236,6 +2236,10 @@ config RANDOMIZE_MEMORY_PHYSICAL_PADDING
 
 	   If unsure, leave at the default value.
 
+# Module section starts just after the end of the kernel module
+config DYNAMIC_MODULE_BASE
+	bool
+
 config X86_GLOBAL_STACKPROTECTOR
 	bool "Stack cookie using a global variable"
 	depends on CC_STACKPROTECTOR_AUTO
diff --git a/arch/x86/include/asm/pgtable_64_types.h b/arch/x86/include/asm/pgtable_64_types.h
index d5c21a382475..d4d3b21d5b3d 100644
--- a/arch/x86/include/asm/pgtable_64_types.h
+++ b/arch/x86/include/asm/pgtable_64_types.h
@@ -7,6 +7,7 @@
 #ifndef __ASSEMBLY__
 #include <linux/types.h>
 #include <asm/kaslr.h>
+#include <asm/sections.h>
 
 /*
  * These are used to make use of C type-checking..
@@ -126,7 +127,12 @@ extern unsigned int ptrs_per_p4d;
 
 #define VMALLOC_END		(VMALLOC_START + (VMALLOC_SIZE_TB << 40) - 1)
 
+#ifdef CONFIG_DYNAMIC_MODULE_BASE
+#define MODULES_VADDR		ALIGN(((unsigned long)_end + PAGE_SIZE), PMD_SIZE)
+#else
 #define MODULES_VADDR		(__START_KERNEL_map + KERNEL_IMAGE_SIZE)
+#endif
+
 /* The module sections ends with the start of the fixmap */
 #define MODULES_END		_AC(0xffffffffff000000, UL)
 #define MODULES_LEN		(MODULES_END - MODULES_VADDR)
diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
index 2fe60e661227..ea4c498369d8 100644
--- a/arch/x86/kernel/head64.c
+++ b/arch/x86/kernel/head64.c
@@ -384,12 +384,15 @@ asmlinkage __visible void __init x86_64_start_kernel(char * real_mode_data)
 	 * Build-time sanity checks on the kernel image and module
 	 * area mappings. (these are purely build-time and produce no code)
 	 */
+#ifndef CONFIG_DYNAMIC_MODULE_BASE
 	BUILD_BUG_ON(MODULES_VADDR < __START_KERNEL_map);
 	BUILD_BUG_ON(MODULES_VADDR - __START_KERNEL_map < KERNEL_IMAGE_SIZE);
-	BUILD_BUG_ON(MODULES_LEN + KERNEL_IMAGE_SIZE > 2*PUD_SIZE);
+	BUILD_BUG_ON(!IS_ENABLED(CONFIG_RANDOMIZE_BASE_LARGE) &&
+		     MODULES_LEN + KERNEL_IMAGE_SIZE > 2*PUD_SIZE);
 	BUILD_BUG_ON((__START_KERNEL_map & ~PMD_MASK) != 0);
 	BUILD_BUG_ON((MODULES_VADDR & ~PMD_MASK) != 0);
 	BUILD_BUG_ON(!(MODULES_VADDR > __START_KERNEL));
+#endif
 	MAYBE_BUILD_BUG_ON(!(((MODULES_END - 1) & PGDIR_MASK) ==
 				(__START_KERNEL & PGDIR_MASK)));
 	BUILD_BUG_ON(__fix_to_virt(__end_of_fixed_addresses) <= MODULES_END);
diff --git a/arch/x86/mm/dump_pagetables.c b/arch/x86/mm/dump_pagetables.c
index 62a7e9f65dec..6f0b1fa2a71a 100644
--- a/arch/x86/mm/dump_pagetables.c
+++ b/arch/x86/mm/dump_pagetables.c
@@ -104,7 +104,7 @@ static struct addr_marker address_markers[] = {
 	[EFI_END_NR]		= { EFI_VA_END,		"EFI Runtime Services" },
 #endif
 	[HIGH_KERNEL_NR]	= { __START_KERNEL_map,	"High Kernel Mapping" },
-	[MODULES_VADDR_NR]	= { MODULES_VADDR,	"Modules" },
+	[MODULES_VADDR_NR]	= { 0/*MODULES_VADDR*/,	"Modules" },
 	[MODULES_END_NR]	= { MODULES_END,	"End Modules" },
 	[FIXADDR_START_NR]	= { FIXADDR_START,	"Fixmap Area" },
 	[END_OF_SPACE_NR]	= { -1,			NULL }
@@ -599,6 +599,7 @@ static int __init pt_dump_init(void)
 	address_markers[KASAN_SHADOW_START_NR].start_address = KASAN_SHADOW_START;
 	address_markers[KASAN_SHADOW_END_NR].start_address = KASAN_SHADOW_END;
 #endif
+	address_markers[MODULES_VADDR_NR].start_address = MODULES_VADDR;
 #endif
 #ifdef CONFIG_X86_32
 	address_markers[VMALLOC_START_NR].start_address = VMALLOC_START;
-- 
2.16.2.660.g709887971b-goog

[PATCH v2 23/27] x86/modules: Adapt module loading for PIE support

[Thomas Garnier]

Adapt module loading to support PIE relocations. Generate dynamic GOT if
a symbol requires it but no entry exist in the kernel GOT.

Position Independent Executable (PIE) support will allow to extended the
KASLR randomization range below the -2G memory limit.

Signed-off-by: Thomas Garnier <thgarnie@google.com>
---
 arch/x86/Makefile               |   4 +
 arch/x86/include/asm/module.h   |  11 ++
 arch/x86/include/asm/sections.h |   4 +
 arch/x86/kernel/module.c        | 181 +++++++++++++++++++++++++++++++-
 arch/x86/kernel/module.lds      |   3 +
 5 files changed, 198 insertions(+), 5 deletions(-)
 create mode 100644 arch/x86/kernel/module.lds

diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index 16dafc551f3b..f24d200c0d9d 100644
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -135,7 +135,11 @@ else
         KBUILD_CFLAGS += $(cflags-y)
 
         KBUILD_CFLAGS += -mno-red-zone
+ifdef CONFIG_X86_PIE
+        KBUILD_LDFLAGS_MODULE += -T $(srctree)/arch/x86/kernel/module.lds
+else
         KBUILD_CFLAGS += -mcmodel=kernel
+endif
 
         # -funit-at-a-time shrinks the kernel .text considerably
         # unfortunately it makes reading oopses harder.
diff --git a/arch/x86/include/asm/module.h b/arch/x86/include/asm/module.h
index 7948a17febb4..68ff05e14288 100644
--- a/arch/x86/include/asm/module.h
+++ b/arch/x86/include/asm/module.h
@@ -5,12 +5,23 @@
 #include <asm-generic/module.h>
 #include <asm/orc_types.h>
 
+#ifdef CONFIG_X86_PIE
+struct mod_got_sec {
+	struct elf64_shdr	*got;
+	int			got_num_entries;
+	int			got_max_entries;
+};
+#endif
+
 struct mod_arch_specific {
 #ifdef CONFIG_UNWINDER_ORC
 	unsigned int num_orcs;
 	int *orc_unwind_ip;
 	struct orc_entry *orc_unwind;
 #endif
+#ifdef CONFIG_X86_PIE
+	struct mod_got_sec	core;
+#endif
 };
 
 #ifdef CONFIG_X86_64
diff --git a/arch/x86/include/asm/sections.h b/arch/x86/include/asm/sections.h
index cad292f62eed..0bbd9f941573 100644
--- a/arch/x86/include/asm/sections.h
+++ b/arch/x86/include/asm/sections.h
@@ -16,4 +16,8 @@ extern char __end_rodata_hpage_align[];
 extern char __start_got[], __end_got[];
 #endif
 
+#if defined(CONFIG_X86_PIE)
+extern char __start_got[], __end_got[];
+#endif
+
 #endif	/* _ASM_X86_SECTIONS_H */
diff --git a/arch/x86/kernel/module.c b/arch/x86/kernel/module.c
index f58336af095c..88895f3d474b 100644
--- a/arch/x86/kernel/module.c
+++ b/arch/x86/kernel/module.c
@@ -30,6 +30,7 @@
 #include <linux/gfp.h>
 #include <linux/jump_label.h>
 #include <linux/random.h>
+#include <linux/sort.h>
 
 #include <asm/text-patching.h>
 #include <asm/page.h>
@@ -77,6 +78,173 @@ static unsigned long int get_module_load_offset(void)
 }
 #endif
 
+#ifdef CONFIG_X86_PIE
+static u64 find_got_kernel_entry(Elf64_Sym *sym, const Elf64_Rela *rela)
+{
+	u64 *pos;
+
+	for (pos = (u64*)__start_got; pos < (u64*)__end_got; pos++) {
+		if (*pos == sym->st_value)
+			return (u64)pos + rela->r_addend;
+	}
+
+	return 0;
+}
+
+static u64 module_emit_got_entry(struct module *mod, void *loc,
+				 const Elf64_Rela *rela, Elf64_Sym *sym)
+{
+	struct mod_got_sec *gotsec = &mod->arch.core;
+	u64 *got = (u64*)gotsec->got->sh_addr;
+	int i = gotsec->got_num_entries;
+	u64 ret;
+
+	/* Check if we can use the kernel GOT */
+	ret = find_got_kernel_entry(sym, rela);
+	if (ret)
+		return ret;
+
+	got[i] = sym->st_value;
+
+	/*
+	 * Check if the entry we just created is a duplicate. Given that the
+	 * relocations are sorted, this will be the last entry we allocated.
+	 * (if one exists).
+	 */
+	if (i > 0 && got[i] == got[i - 2]) {
+		ret = (u64)&got[i - 1];
+	} else {
+		gotsec->got_num_entries++;
+		BUG_ON(gotsec->got_num_entries > gotsec->got_max_entries);
+		ret = (u64)&got[i];
+	}
+
+	return ret + rela->r_addend;
+}
+
+#define cmp_3way(a,b)	((a) < (b) ? -1 : (a) > (b))
+
+static int cmp_rela(const void *a, const void *b)
+{
+	const Elf64_Rela *x = a, *y = b;
+	int i;
+
+	/* sort by type, symbol index and addend */
+	i = cmp_3way(ELF64_R_TYPE(x->r_info), ELF64_R_TYPE(y->r_info));
+	if (i == 0)
+		i = cmp_3way(ELF64_R_SYM(x->r_info), ELF64_R_SYM(y->r_info));
+	if (i == 0)
+		i = cmp_3way(x->r_addend, y->r_addend);
+	return i;
+}
+
+static bool duplicate_rel(const Elf64_Rela *rela, int num)
+{
+	/*
+	 * Entries are sorted by type, symbol index and addend. That means
+	 * that, if a duplicate entry exists, it must be in the preceding
+	 * slot.
+	 */
+	return num > 0 && cmp_rela(rela + num, rela + num - 1) == 0;
+}
+
+static unsigned int count_gots(Elf64_Sym *syms, Elf64_Rela *rela, int num)
+{
+	unsigned int ret = 0;
+	Elf64_Sym *s;
+	int i;
+
+	for (i = 0; i < num; i++) {
+		switch (ELF64_R_TYPE(rela[i].r_info)) {
+		case R_X86_64_GOTPCREL:
+			s = syms + ELF64_R_SYM(rela[i].r_info);
+
+			/*
+			 * Use the kernel GOT when possible, else reserve a
+			 * custom one for this module.
+			 */
+			if (!duplicate_rel(rela, i) &&
+			    !find_got_kernel_entry(s, rela + i))
+				ret++;
+			break;
+		}
+	}
+	return ret;
+}
+
+/*
+ * Generate GOT entries for GOTPCREL relocations that do not exists in the
+ * kernel GOT. Based on arm64 module-plts implementation.
+ */
+int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs,
+			      char *secstrings, struct module *mod)
+{
+	unsigned long gots = 0;
+	Elf_Shdr *symtab = NULL;
+	Elf64_Sym *syms = NULL;
+	char *strings, *name;
+	int i;
+
+	/*
+	 * Find the empty .got section so we can expand it to store the PLT
+	 * entries. Record the symtab address as well.
+	 */
+	for (i = 0; i < ehdr->e_shnum; i++) {
+		if (!strcmp(secstrings + sechdrs[i].sh_name, ".got")) {
+			mod->arch.core.got = sechdrs + i;
+		} else if (sechdrs[i].sh_type == SHT_SYMTAB) {
+			symtab = sechdrs + i;
+			syms = (Elf64_Sym *)symtab->sh_addr;
+		}
+	}
+
+	if (!mod->arch.core.got) {
+		pr_err("%s: module GOT section missing\n", mod->name);
+		return -ENOEXEC;
+	}
+	if (!syms) {
+		pr_err("%s: module symtab section missing\n", mod->name);
+		return -ENOEXEC;
+	}
+
+	for (i = 0; i < ehdr->e_shnum; i++) {
+		Elf64_Rela *rels = (void *)ehdr + sechdrs[i].sh_offset;
+		int numrels = sechdrs[i].sh_size / sizeof(Elf64_Rela);
+
+		if (sechdrs[i].sh_type != SHT_RELA)
+			continue;
+
+		/* sort by type, symbol index and addend */
+		sort(rels, numrels, sizeof(Elf64_Rela), cmp_rela, NULL);
+
+		gots += count_gots(syms, rels, numrels);
+	}
+
+	mod->arch.core.got->sh_type = SHT_NOBITS;
+	mod->arch.core.got->sh_flags = SHF_ALLOC;
+	mod->arch.core.got->sh_addralign = L1_CACHE_BYTES;
+	mod->arch.core.got->sh_size = (gots + 1) * sizeof(u64);
+	mod->arch.core.got_num_entries = 0;
+	mod->arch.core.got_max_entries = gots;
+
+	/*
+	 * If a _GLOBAL_OFFSET_TABLE_ symbol exists, make it absolute for
+	 * modules to correctly reference it. Similar to s390 implementation.
+	 */
+	strings = (void *) ehdr + sechdrs[symtab->sh_link].sh_offset;
+	for (i = 0; i < symtab->sh_size/sizeof(Elf_Sym); i++) {
+		if (syms[i].st_shndx != SHN_UNDEF)
+			continue;
+		name = strings + syms[i].st_name;
+		if (!strcmp(name, "_GLOBAL_OFFSET_TABLE_")) {
+			syms[i].st_shndx = SHN_ABS;
+			break;
+		}
+	}
+	return 0;
+}
+#endif
+
 void *module_alloc(unsigned long size)
 {
 	void *p;
@@ -190,16 +358,20 @@ int apply_relocate_add(Elf64_Shdr *sechdrs,
 			if ((s64)val != *(s32 *)loc)
 				goto overflow;
 			break;
+#ifdef CONFIG_X86_PIE
+		case R_X86_64_GOTPCREL:
+			val = module_emit_got_entry(me, loc, rel + i, sym);
+			/* fallthrough */
+#endif
 		case R_X86_64_PC32:
 		case R_X86_64_PLT32:
 			if (*(u32 *)loc != 0)
 				goto invalid_relocation;
 			val -= (u64)loc;
 			*(u32 *)loc = val;
-#if 0
-			if ((s64)val != *(s32 *)loc)
+			if (IS_ENABLED(CONFIG_X86_PIE) &&
+			    (s64)val != *(s32 *)loc)
 				goto overflow;
-#endif
 			break;
 		default:
 			pr_err("%s: Unknown rela relocation: %llu\n",
@@ -217,8 +389,7 @@ int apply_relocate_add(Elf64_Shdr *sechdrs,
 overflow:
 	pr_err("overflow in relocation type %d val %Lx\n",
 	       (int)ELF64_R_TYPE(rel[i].r_info), val);
-	pr_err("`%s' likely not compiled with -mcmodel=kernel\n",
-	       me->name);
+	pr_err("`%s' likely too far from the kernel\n", me->name);
 	return -ENOEXEC;
 }
 #endif
diff --git a/arch/x86/kernel/module.lds b/arch/x86/kernel/module.lds
new file mode 100644
index 000000000000..fd6e95a4b454
--- /dev/null
+++ b/arch/x86/kernel/module.lds
@@ -0,0 +1,3 @@
+SECTIONS {
+	.got (NOLOAD) : { BYTE(0) }
+}
-- 
2.16.2.660.g709887971b-goog

[PATCH v2 24/27] x86/mm: Make the x86 GOT read-only

[Thomas Garnier]

The GOT is changed during early boot when relocations are applied. Make
it read-only directly. This table exists only for PIE binary.

Position Independent Executable (PIE) support will allow to extended the
KASLR randomization range below the -2G memory limit.

Signed-off-by: Thomas Garnier <thgarnie@google.com>
---
 include/asm-generic/vmlinux.lds.h | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index 1ab0e520d6fc..89398d042f78 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -295,6 +295,17 @@
 	VMLINUX_SYMBOL(__end_ro_after_init) = .;
 #endif
 
+#ifdef CONFIG_X86_PIE
+#define RO_GOT_X86							\
+	.got        : AT(ADDR(.got) - LOAD_OFFSET) {			\
+		VMLINUX_SYMBOL(__start_got) = .;			\
+		*(.got);						\
+		VMLINUX_SYMBOL(__end_got) = .;				\
+	}
+#else
+#define RO_GOT_X86
+#endif
+
 /*
  * Read only Data
  */
@@ -351,6 +362,7 @@
 		VMLINUX_SYMBOL(__end_builtin_fw) = .;			\
 	}								\
 									\
+	RO_GOT_X86							\
 	TRACEDATA							\
 									\
 	/* Kernel symbol table: Normal symbols */			\
-- 
2.16.2.660.g709887971b-goog

[PATCH v2 25/27] x86/pie: Add option to build the kernel as PIE

[Thomas Garnier]

Add the CONFIG_X86_PIE option which builds the kernel as a Position
Independent Executable (PIE). The kernel is currently build with the
mcmodel=kernel option which forces it to stay on the top 2G of the
virtual address space. With PIE, the kernel will be able to move below
the current limit.

The --emit-relocs linker option was kept instead of using -pie to limit
the impact on mapped sections. Any incompatible relocation will be
catch by the arch/x86/tools/relocs binary at compile time.

If segment based stack cookies are enabled, try to use the compiler
option to select the segment register. If not available, automatically
enabled global stack cookie in auto mode. Otherwise, recommend
compiler update or global stack cookie option.

Performance/Size impact:

Size of vmlinux (Default configuration):
 File size:
 - PIE disabled: +0.18%
 - PIE enabled: -1.977% (less relocations)
 .text section:
 - PIE disabled: same
 - PIE enabled: same

Size of vmlinux (Ubuntu configuration):
 File size:
 - PIE disabled: +0.21%
 - PIE enabled: +10%
 .text section:
 - PIE disabled: same
 - PIE enabled: +0.001%

The size increase is mainly due to not having access to the 32-bit signed
relocation that can be used with mcmodel=kernel. A small part is due to reduced
optimization for PIE code. This bug [1] was opened with gcc to provide a better
code generation for kernel PIE.

Hackbench (50% and 1600% on thread/process for pipe/sockets):
 - PIE disabled: no significant change (avg -/+ 0.5% on latest test).
 - PIE enabled: between -1% to +1% in average (default and Ubuntu config).

Kernbench (average of 10 Half and Optimal runs):
 Elapsed Time:
 - PIE disabled: no significant change (avg -0.5%)
 - PIE enabled: average -0.5% to +0.5%
 System Time:
 - PIE disabled: no significant change (avg -0.1%)
 - PIE enabled: average -0.4% to +0.4%.

[1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82303

Signed-off-by: Thomas Garnier <thgarnie@google.com>

merge pie
---
 arch/x86/Kconfig  |  8 ++++++++
 arch/x86/Makefile | 45 ++++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 52 insertions(+), 1 deletion(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index df4134fd3247..4b1615e661d6 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -2252,6 +2252,14 @@ config X86_GLOBAL_STACKPROTECTOR
 
 	   If unsure, say N
 
+config X86_PIE
+	bool
+	depends on X86_64
+	select DEFAULT_HIDDEN
+	select WEAK_PROVIDE_HIDDEN
+	select DYNAMIC_MODULE_BASE
+	select MODULE_REL_CRCS if MODVERSIONS
+
 config HOTPLUG_CPU
 	bool "Support for hot-pluggable CPUs"
 	depends on SMP
diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index f24d200c0d9d..ab0cf88c7059 100644
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -61,6 +61,8 @@ endif
 KBUILD_CFLAGS += -mno-sse -mno-mmx -mno-sse2 -mno-3dnow
 KBUILD_CFLAGS += $(call cc-option,-mno-avx,)
 
+stackglobal := $(call cc-option-yn, -mstack-protector-guard=global)
+
 ifeq ($(CONFIG_X86_32),y)
         BITS := 32
         UTS_MACHINE := i386
@@ -136,7 +138,48 @@ else
 
         KBUILD_CFLAGS += -mno-red-zone
 ifdef CONFIG_X86_PIE
+        KBUILD_CFLAGS += -fPIE
         KBUILD_LDFLAGS_MODULE += -T $(srctree)/arch/x86/kernel/module.lds
+
+        # Relax relocation in both CFLAGS and LDFLAGS to support older compilers
+        KBUILD_CFLAGS += $(call cc-option,-Wa$(comma)-mrelax-relocations=no)
+        LDFLAGS_vmlinux += $(call ld-option,--no-relax)
+        KBUILD_LDFLAGS_MODULE += $(call ld-option,--no-relax)
+
+        # Stack validation is not yet support due to self-referenced switches
+ifdef CONFIG_STACK_VALIDATION
+        $(warning CONFIG_STACK_VALIDATION is not yet supported for x86_64 pie \
+	        build.)
+        SKIP_STACK_VALIDATION := 1
+        export SKIP_STACK_VALIDATION
+endif
+
+ifndef CONFIG_CC_STACKPROTECTOR_NONE
+ifndef CONFIG_X86_GLOBAL_STACKPROTECTOR
+        stackseg-flag := -mstack-protector-guard-reg=%gs
+        ifeq ($(call cc-option-yn,$(stackseg-flag)),n)
+                # Try to enable global stack cookie if possible
+                ifeq ($(stackglobal), y)
+                        $(warning Cannot use CONFIG_CC_STACKPROTECTOR_* while \
+                                building a position independent kernel. \
+                                Default to global stack protector \
+                                (CONFIG_X86_GLOBAL_STACKPROTECTOR).)
+                        CONFIG_X86_GLOBAL_STACKPROTECTOR := y
+                        KBUILD_CFLAGS += -DCONFIG_X86_GLOBAL_STACKPROTECTOR
+                        KBUILD_AFLAGS += -DCONFIG_X86_GLOBAL_STACKPROTECTOR
+                else
+                        $(error echo Cannot use \
+                                CONFIG_CC_STACKPROTECTOR_(REGULAR|STRONG|AUTO) \
+                                while building a position independent binary. \
+                                Update your compiler or use \
+                                CONFIG_X86_GLOBAL_STACKPROTECTOR)
+                endif
+        else
+                KBUILD_CFLAGS += $(stackseg-flag)
+        endif
+endif
+endif
+
 else
         KBUILD_CFLAGS += -mcmodel=kernel
 endif
@@ -147,7 +190,7 @@ endif
 endif
 
 ifdef CONFIG_X86_GLOBAL_STACKPROTECTOR
-        ifeq ($(call cc-option, -mstack-protector-guard=global),)
+        ifeq ($(stackglobal), n)
                 $(error Cannot use CONFIG_X86_GLOBAL_STACKPROTECTOR: \
                         -mstack-protector-guard=global not supported \
                         by compiler)
-- 
2.16.2.660.g709887971b-goog

[PATCH v2 26/27] x86/relocs: Add option to generate 64-bit relocations

[Thomas Garnier]

The x86 relocation tool generates a list of 32-bit signed integers. There
was no need to use 64-bit integers because all addresses where above the 2G
top of the memory.

This change add a large-reloc option to generate 64-bit unsigned integers.
It can be used when the kernel plan to go below the top 2G and 32-bit
integers are not enough.

Signed-off-by: Thomas Garnier <thgarnie@google.com>
---
 arch/x86/tools/relocs.c        | 60 +++++++++++++++++++++++++++-------
 arch/x86/tools/relocs.h        |  4 +--
 arch/x86/tools/relocs_common.c | 15 ++++++---
 3 files changed, 60 insertions(+), 19 deletions(-)

diff --git a/arch/x86/tools/relocs.c b/arch/x86/tools/relocs.c
index 29283ad3950f..a29cccceaac6 100644
--- a/arch/x86/tools/relocs.c
+++ b/arch/x86/tools/relocs.c
@@ -13,8 +13,14 @@
 
 static Elf_Ehdr ehdr;
 
+#if ELF_BITS == 64
+typedef uint64_t rel_off_t;
+#else
+typedef uint32_t rel_off_t;
+#endif
+
 struct relocs {
-	uint32_t	*offset;
+	rel_off_t	*offset;
 	unsigned long	count;
 	unsigned long	size;
 };
@@ -685,7 +691,7 @@ static void print_absolute_relocs(void)
 		printf("\n");
 }
 
-static void add_reloc(struct relocs *r, uint32_t offset)
+static void add_reloc(struct relocs *r, rel_off_t offset)
 {
 	if (r->count == r->size) {
 		unsigned long newsize = r->size + 50000;
@@ -1061,26 +1067,48 @@ static void sort_relocs(struct relocs *r)
 	qsort(r->offset, r->count, sizeof(r->offset[0]), cmp_relocs);
 }
 
-static int write32(uint32_t v, FILE *f)
+static int write32(rel_off_t rel, FILE *f)
 {
-	unsigned char buf[4];
+	unsigned char buf[sizeof(uint32_t)];
+	uint32_t v = (uint32_t)rel;
 
 	put_unaligned_le32(v, buf);
-	return fwrite(buf, 1, 4, f) == 4 ? 0 : -1;
+	return fwrite(buf, 1, sizeof(buf), f) == sizeof(buf) ? 0 : -1;
 }
 
-static int write32_as_text(uint32_t v, FILE *f)
+static int write32_as_text(rel_off_t rel, FILE *f)
 {
+	uint32_t v = (uint32_t)rel;
 	return fprintf(f, "\t.long 0x%08"PRIx32"\n", v) > 0 ? 0 : -1;
 }
 
-static void emit_relocs(int as_text, int use_real_mode)
+static int write64(rel_off_t rel, FILE *f)
+{
+	unsigned char buf[sizeof(uint64_t)];
+	uint64_t v = (uint64_t)rel;
+
+	put_unaligned_le64(v, buf);
+	return fwrite(buf, 1, sizeof(buf), f) == sizeof(buf) ? 0 : -1;
+}
+
+static int write64_as_text(rel_off_t rel, FILE *f)
+{
+	uint64_t v = (uint64_t)rel;
+	return fprintf(f, "\t.quad 0x%016"PRIx64"\n", v) > 0 ? 0 : -1;
+}
+
+static void emit_relocs(int as_text, int use_real_mode, int use_large_reloc)
 {
 	int i;
-	int (*write_reloc)(uint32_t, FILE *) = write32;
+	int (*write_reloc)(rel_off_t, FILE *);
 	int (*do_reloc)(struct section *sec, Elf_Rel *rel, Elf_Sym *sym,
 			const char *symname);
 
+	if (use_large_reloc)
+		write_reloc = write64;
+	else
+		write_reloc = write32;
+
 #if ELF_BITS == 64
 	if (!use_real_mode)
 		do_reloc = do_reloc64;
@@ -1091,6 +1119,9 @@ static void emit_relocs(int as_text, int use_real_mode)
 		do_reloc = do_reloc32;
 	else
 		do_reloc = do_reloc_real;
+
+	/* Large relocations only for 64-bit */
+	use_large_reloc = 0;
 #endif
 
 	/* Collect up the relocations */
@@ -1114,8 +1145,13 @@ static void emit_relocs(int as_text, int use_real_mode)
 		 * gas will like.
 		 */
 		printf(".section \".data.reloc\",\"a\"\n");
-		printf(".balign 4\n");
-		write_reloc = write32_as_text;
+		if (use_large_reloc) {
+			printf(".balign 8\n");
+			write_reloc = write64_as_text;
+		} else {
+			printf(".balign 4\n");
+			write_reloc = write32_as_text;
+		}
 	}
 
 	if (use_real_mode) {
@@ -1183,7 +1219,7 @@ static void print_reloc_info(void)
 
 void process(FILE *fp, int use_real_mode, int as_text,
 	     int show_absolute_syms, int show_absolute_relocs,
-	     int show_reloc_info)
+	     int show_reloc_info, int use_large_reloc)
 {
 	regex_init(use_real_mode);
 	read_ehdr(fp);
@@ -1206,5 +1242,5 @@ void process(FILE *fp, int use_real_mode, int as_text,
 		print_reloc_info();
 		return;
 	}
-	emit_relocs(as_text, use_real_mode);
+	emit_relocs(as_text, use_real_mode, use_large_reloc);
 }
diff --git a/arch/x86/tools/relocs.h b/arch/x86/tools/relocs.h
index 43c83c0fd22c..3d401da59df7 100644
--- a/arch/x86/tools/relocs.h
+++ b/arch/x86/tools/relocs.h
@@ -31,8 +31,8 @@ enum symtype {
 
 void process_32(FILE *fp, int use_real_mode, int as_text,
 		int show_absolute_syms, int show_absolute_relocs,
-		int show_reloc_info);
+		int show_reloc_info, int use_large_reloc);
 void process_64(FILE *fp, int use_real_mode, int as_text,
 		int show_absolute_syms, int show_absolute_relocs,
-		int show_reloc_info);
+		int show_reloc_info, int use_large_reloc);
 #endif /* RELOCS_H */
diff --git a/arch/x86/tools/relocs_common.c b/arch/x86/tools/relocs_common.c
index 6634352a20bc..11f49adf1c06 100644
--- a/arch/x86/tools/relocs_common.c
+++ b/arch/x86/tools/relocs_common.c
@@ -12,14 +12,14 @@ void die(char *fmt, ...)
 
 static void usage(void)
 {
-	die("relocs [--abs-syms|--abs-relocs|--reloc-info|--text|--realmode]" \
-	    " vmlinux\n");
+	die("relocs [--abs-syms|--abs-relocs|--reloc-info|--text|--realmode|" \
+	    "--large-reloc]  vmlinux\n");
 }
 
 int main(int argc, char **argv)
 {
 	int show_absolute_syms, show_absolute_relocs, show_reloc_info;
-	int as_text, use_real_mode;
+	int as_text, use_real_mode, use_large_reloc;
 	const char *fname;
 	FILE *fp;
 	int i;
@@ -30,6 +30,7 @@ int main(int argc, char **argv)
 	show_reloc_info = 0;
 	as_text = 0;
 	use_real_mode = 0;
+	use_large_reloc = 0;
 	fname = NULL;
 	for (i = 1; i < argc; i++) {
 		char *arg = argv[i];
@@ -54,6 +55,10 @@ int main(int argc, char **argv)
 				use_real_mode = 1;
 				continue;
 			}
+			if (strcmp(arg, "--large-reloc") == 0) {
+				use_large_reloc = 1;
+				continue;
+			}
 		}
 		else if (!fname) {
 			fname = arg;
@@ -75,11 +80,11 @@ int main(int argc, char **argv)
 	if (e_ident[EI_CLASS] == ELFCLASS64)
 		process_64(fp, use_real_mode, as_text,
 			   show_absolute_syms, show_absolute_relocs,
-			   show_reloc_info);
+			   show_reloc_info, use_large_reloc);
 	else
 		process_32(fp, use_real_mode, as_text,
 			   show_absolute_syms, show_absolute_relocs,
-			   show_reloc_info);
+			   show_reloc_info, use_large_reloc);
 	fclose(fp);
 	return 0;
 }
-- 
2.16.2.660.g709887971b-goog

[PATCH v2 27/27] x86/kaslr: Add option to extend KASLR range from 1GB to 3GB

[Thomas Garnier]

Add a new CONFIG_RANDOMIZE_BASE_LARGE option to benefit from PIE
support. It increases the KASLR range from 1GB to 3GB. The new range
stars at 0xffffffff00000000 just above the EFI memory region. This
option is off by default.

The boot code is adapted to create the appropriate page table spanning
three PUD pages.

The relocation table uses 64-bit integers generated with the updated
relocation tool with the large-reloc option.

Signed-off-by: Thomas Garnier <thgarnie@google.com>
---
 arch/x86/Kconfig                     | 21 +++++++++++++++++++++
 arch/x86/boot/compressed/Makefile    |  5 +++++
 arch/x86/boot/compressed/misc.c      | 10 +++++++++-
 arch/x86/include/asm/page_64_types.h |  9 +++++++++
 arch/x86/kernel/head64.c             | 15 ++++++++++++---
 arch/x86/kernel/head_64.S            | 11 ++++++++++-
 6 files changed, 66 insertions(+), 5 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 4b1615e661d6..7ea69cb0153f 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -2260,6 +2260,27 @@ config X86_PIE
 	select DYNAMIC_MODULE_BASE
 	select MODULE_REL_CRCS if MODVERSIONS
 
+config RANDOMIZE_BASE_LARGE
+	bool "Increase the randomization range of the kernel image"
+	depends on X86_64 && RANDOMIZE_BASE
+	select X86_PIE
+	select X86_MODULE_PLTS if MODULES
+	default n
+	---help---
+	  Build the kernel as a Position Independent Executable (PIE) and
+	  increase the available randomization range from 1GB to 3GB.
+
+	  This option impacts performance on kernel CPU intensive workloads up
+	  to 10% due to PIE generated code. Impact on user-mode processes and
+	  typical usage would be significantly less (0.50% when you build the
+	  kernel).
+
+	  The kernel and modules will generate slightly more assembly (1 to 2%
+	  increase on the .text sections). The vmlinux binary will be
+	  significantly smaller due to less relocations.
+
+	  If unsure say N
+
 config HOTPLUG_CPU
 	bool "Support for hot-pluggable CPUs"
 	depends on SMP
diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile
index 1f734cd98fd3..fb72f53defd0 100644
--- a/arch/x86/boot/compressed/Makefile
+++ b/arch/x86/boot/compressed/Makefile
@@ -116,7 +116,12 @@ $(obj)/vmlinux.bin: vmlinux FORCE
 
 targets += $(patsubst $(obj)/%,%,$(vmlinux-objs-y)) vmlinux.bin.all vmlinux.relocs
 
+# Large randomization require bigger relocation table
+ifeq ($(CONFIG_RANDOMIZE_BASE_LARGE),y)
+CMD_RELOCS = arch/x86/tools/relocs --large-reloc
+else
 CMD_RELOCS = arch/x86/tools/relocs
+endif
 quiet_cmd_relocs = RELOCS  $@
       cmd_relocs = $(CMD_RELOCS) $< > $@;$(CMD_RELOCS) --abs-relocs $<
 $(obj)/vmlinux.relocs: vmlinux FORCE
diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c
index b50c42455e25..746a968690d5 100644
--- a/arch/x86/boot/compressed/misc.c
+++ b/arch/x86/boot/compressed/misc.c
@@ -170,10 +170,18 @@ void __puthex(unsigned long value)
 }
 
 #if CONFIG_X86_NEED_RELOCS
+
+/* Large randomization go lower than -2G and use large relocation table */
+#ifdef CONFIG_RANDOMIZE_BASE_LARGE
+typedef long rel_t;
+#else
+typedef int rel_t;
+#endif
+
 static void handle_relocations(void *output, unsigned long output_len,
 			       unsigned long virt_addr)
 {
-	int *reloc;
+	rel_t *reloc;
 	unsigned long delta, map, ptr;
 	unsigned long min_addr = (unsigned long)output;
 	unsigned long max_addr = min_addr + (VO___bss_start - VO__text);
diff --git a/arch/x86/include/asm/page_64_types.h b/arch/x86/include/asm/page_64_types.h
index 2c5a966dc222..85ea681421d2 100644
--- a/arch/x86/include/asm/page_64_types.h
+++ b/arch/x86/include/asm/page_64_types.h
@@ -46,7 +46,11 @@
 #define __PAGE_OFFSET           __PAGE_OFFSET_BASE_L4
 #endif /* CONFIG_DYNAMIC_MEMORY_LAYOUT */
 
+#ifdef CONFIG_RANDOMIZE_BASE_LARGE
+#define __START_KERNEL_map	_AC(0xffffffff00000000, UL)
+#else
 #define __START_KERNEL_map	_AC(0xffffffff80000000, UL)
+#endif /* CONFIG_RANDOMIZE_BASE_LARGE */
 
 /* See Documentation/x86/x86_64/mm.txt for a description of the memory map. */
 
@@ -64,9 +68,14 @@
  * 512MiB by default, leaving 1.5GiB for modules once the page tables
  * are fully set up. If kernel ASLR is configured, it can extend the
  * kernel page table mapping, reducing the size of the modules area.
+ * On PIE, we relocate the binary 2G lower so add this extra space.
  */
 #if defined(CONFIG_RANDOMIZE_BASE)
+#ifdef CONFIG_RANDOMIZE_BASE_LARGE
+#define KERNEL_IMAGE_SIZE	(_AC(3, UL) * 1024 * 1024 * 1024)
+#else
 #define KERNEL_IMAGE_SIZE	(1024 * 1024 * 1024)
+#endif
 #else
 #define KERNEL_IMAGE_SIZE	(512 * 1024 * 1024)
 #endif
diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
index ea4c498369d8..577b47381ba2 100644
--- a/arch/x86/kernel/head64.c
+++ b/arch/x86/kernel/head64.c
@@ -63,6 +63,7 @@ EXPORT_SYMBOL(vmemmap_base);
 #endif
 
 #define __head	__section(.head.text)
+#define pud_count(x)   (((x + (PUD_SIZE - 1)) & ~(PUD_SIZE - 1)) >> PUD_SHIFT)
 
 /* Required for read_cr3 when building as PIE */
 unsigned long __force_order;
@@ -112,6 +113,8 @@ unsigned long __head __startup_64(unsigned long physaddr,
 {
 	unsigned long load_delta, *p;
 	unsigned long pgtable_flags;
+	unsigned long level3_kernel_start, level3_kernel_count;
+	unsigned long level3_fixmap_start;
 	pgdval_t *pgd;
 	p4dval_t *p4d;
 	pudval_t *pud;
@@ -142,6 +145,11 @@ unsigned long __head __startup_64(unsigned long physaddr,
 	/* Include the SME encryption mask in the fixup value */
 	load_delta += sme_get_me_mask();
 
+	/* Look at the randomization spread to adapt page table used */
+	level3_kernel_start = pud_index(__START_KERNEL_map);
+	level3_kernel_count = pud_count(KERNEL_IMAGE_SIZE);
+	level3_fixmap_start = level3_kernel_start + level3_kernel_count;
+
 	/* Fixup the physical addresses in the page table */
 
 	pgd = fixup_pointer(&early_top_pgt, physaddr);
@@ -158,8 +166,9 @@ unsigned long __head __startup_64(unsigned long physaddr,
 	}
 
 	pud = fixup_pointer(&level3_kernel_pgt, physaddr);
-	pud[510] += load_delta;
-	pud[511] += load_delta;
+	for (i = 0; i < level3_kernel_count; i++)
+		pud[level3_kernel_start + i] += load_delta;
+	pud[level3_fixmap_start] += load_delta;
 
 	pmd = fixup_pointer(level2_fixmap_pgt, physaddr);
 	pmd[506] += load_delta;
@@ -214,7 +223,7 @@ unsigned long __head __startup_64(unsigned long physaddr,
 	 */
 
 	pmd = fixup_pointer(level2_kernel_pgt, physaddr);
-	for (i = 0; i < PTRS_PER_PMD; i++) {
+	for (i = 0; i < PTRS_PER_PMD * level3_kernel_count; i++) {
 		if (pmd[i] & _PAGE_PRESENT)
 			pmd[i] += load_delta;
 	}
diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index 87624e1fe22f..c86d9262015f 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -41,12 +41,16 @@
 
 #define l4_index(x)	(((x) >> 39) & 511)
 #define pud_index(x)	(((x) >> PUD_SHIFT) & (PTRS_PER_PUD-1))
+#define pud_count(x)   (((x + (PUD_SIZE - 1)) & ~(PUD_SIZE - 1)) >> PUD_SHIFT)
 
 L4_PAGE_OFFSET = l4_index(__PAGE_OFFSET_BASE_L4)
 L4_START_KERNEL = l4_index(__START_KERNEL_map)
 
 L3_START_KERNEL = pud_index(__START_KERNEL_map)
 
+/* Adapt page table L3 space based on range of randomization */
+L3_KERNEL_ENTRY_COUNT = pud_count(KERNEL_IMAGE_SIZE)
+
 	.text
 	__HEAD
 	.code64
@@ -436,7 +440,12 @@ NEXT_PAGE(level4_kernel_pgt)
 NEXT_PAGE(level3_kernel_pgt)
 	.fill	L3_START_KERNEL,8,0
 	/* (2^48-(2*1024*1024*1024)-((2^39)*511))/(2^30) = 510 */
-	.quad	level2_kernel_pgt - __START_KERNEL_map + _KERNPG_TABLE_NOENC
+	i = 0
+	.rept	L3_KERNEL_ENTRY_COUNT
+	.quad	level2_kernel_pgt - __START_KERNEL_map + _KERNPG_TABLE_NOENC \
+		+ PAGE_SIZE*i
+	i = i + 1
+	.endr
 	.quad	level2_fixmap_pgt - __START_KERNEL_map + _PAGE_TABLE_NOENC
 
 NEXT_PAGE(level2_kernel_pgt)
-- 
2.16.2.660.g709887971b-goog

Re: [PATCH v2 00/27] x86: PIE support and option to extend KASLR randomization

[Pavel Machek]

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Hi!

> These patches make the changes necessary to build the kernel as Position
> Independent Executable (PIE) on x86_64. A PIE kernel can be relocated below
> the top 2G of the virtual address space. It allows to optionally extend the
> KASLR randomization range from 1G to 3G.

Would you explain why PIE code is good idea?

You are adding less than 2 bits of randomness. Cost is new config
option, some size and performance impact, and more than 1000 lines of
code...

Is there some grand plan of adding 30 more bits of randomness with
future patch or something?
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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