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Date: Wed, 8 Apr 2020 23:35:08 +0200
From: Peter Zijlstra <peterz@...radead.org>
To: Josh Poimboeuf <jpoimboe@...hat.com>
Cc: Alexandre Chartre <alexandre.chartre@...cle.com>, x86@...nel.org,
linux-kernel@...r.kernel.org, jthierry@...hat.com,
tglx@...utronix.de
Subject: Re: [PATCH V2 9/9] x86/speculation: Remove all
ANNOTATE_NOSPEC_ALTERNATIVE directives
On Tue, Apr 07, 2020 at 07:27:39PM +0200, Peter Zijlstra wrote:
> On Tue, Apr 07, 2020 at 11:28:38AM -0500, Josh Poimboeuf wrote:
> > Again, we should warn on stack changes inside alternatives, and then
> > look at converting RSB and retpolines to use static branches so they
> > have deterministic stacks.
>
> I don't think we need static brancher, we should just out-of-line the
> whole thing.
>
> Let me sort this CFI error Thomas is getting and then I'll attempt a
> patch along the lines I outlined in earlier emails.
Something like so.. seems to build and boot.
---
From: Peter Zijlstra (Intel) <peterz@...radead.org>
Subject: x86: Out-of-line retpoline
Since GCC generated code already uses out-of-line retpolines and objtool
has trouble with retpolines in alternatives, out-of-line them entirely.
This will enable objtool (once it's been taught a few more tricks) to
generate valid ORC data for the out-of-line copies, which means we can
correctly and reliably unwind through a retpoline.
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
arch/x86/crypto/aesni-intel_asm.S | 4 +--
arch/x86/crypto/camellia-aesni-avx-asm_64.S | 2 +-
arch/x86/crypto/camellia-aesni-avx2-asm_64.S | 2 +-
arch/x86/crypto/crc32c-pcl-intel-asm_64.S | 26 ++++++++---------
arch/x86/entry/entry_32.S | 6 ++--
arch/x86/entry/entry_64.S | 2 +-
arch/x86/include/asm/asm-prototypes.h | 8 ++++--
arch/x86/include/asm/nospec-branch.h | 42 ++++------------------------
arch/x86/kernel/ftrace_32.S | 2 +-
arch/x86/kernel/ftrace_64.S | 4 +--
arch/x86/lib/checksum_32.S | 4 +--
arch/x86/lib/retpoline.S | 27 +++++++++++++++---
arch/x86/platform/efi/efi_stub_64.S | 2 +-
13 files changed, 62 insertions(+), 69 deletions(-)
diff --git a/arch/x86/crypto/aesni-intel_asm.S b/arch/x86/crypto/aesni-intel_asm.S
index cad6e1bfa7d5..54e7d15dbd0d 100644
--- a/arch/x86/crypto/aesni-intel_asm.S
+++ b/arch/x86/crypto/aesni-intel_asm.S
@@ -2758,7 +2758,7 @@ SYM_FUNC_START(aesni_xts_crypt8)
pxor INC, STATE4
movdqu IV, 0x30(OUTP)
- CALL_NOSPEC %r11
+ CALL_NOSPEC r11
movdqu 0x00(OUTP), INC
pxor INC, STATE1
@@ -2803,7 +2803,7 @@ SYM_FUNC_START(aesni_xts_crypt8)
_aesni_gf128mul_x_ble()
movups IV, (IVP)
- CALL_NOSPEC %r11
+ CALL_NOSPEC r11
movdqu 0x40(OUTP), INC
pxor INC, STATE1
diff --git a/arch/x86/crypto/camellia-aesni-avx-asm_64.S b/arch/x86/crypto/camellia-aesni-avx-asm_64.S
index d01ddd73de65..ecc0a9a905c4 100644
--- a/arch/x86/crypto/camellia-aesni-avx-asm_64.S
+++ b/arch/x86/crypto/camellia-aesni-avx-asm_64.S
@@ -1228,7 +1228,7 @@ SYM_FUNC_START_LOCAL(camellia_xts_crypt_16way)
vpxor 14 * 16(%rax), %xmm15, %xmm14;
vpxor 15 * 16(%rax), %xmm15, %xmm15;
- CALL_NOSPEC %r9;
+ CALL_NOSPEC r9;
addq $(16 * 16), %rsp;
diff --git a/arch/x86/crypto/camellia-aesni-avx2-asm_64.S b/arch/x86/crypto/camellia-aesni-avx2-asm_64.S
index 563ef6e83cdd..0907243c501c 100644
--- a/arch/x86/crypto/camellia-aesni-avx2-asm_64.S
+++ b/arch/x86/crypto/camellia-aesni-avx2-asm_64.S
@@ -1339,7 +1339,7 @@ SYM_FUNC_START_LOCAL(camellia_xts_crypt_32way)
vpxor 14 * 32(%rax), %ymm15, %ymm14;
vpxor 15 * 32(%rax), %ymm15, %ymm15;
- CALL_NOSPEC %r9;
+ CALL_NOSPEC r9;
addq $(16 * 32), %rsp;
diff --git a/arch/x86/crypto/crc32c-pcl-intel-asm_64.S b/arch/x86/crypto/crc32c-pcl-intel-asm_64.S
index 0e6690e3618c..8501ec4532f4 100644
--- a/arch/x86/crypto/crc32c-pcl-intel-asm_64.S
+++ b/arch/x86/crypto/crc32c-pcl-intel-asm_64.S
@@ -75,7 +75,7 @@
.text
SYM_FUNC_START(crc_pcl)
-#define bufp %rdi
+#define bufp rdi
#define bufp_dw %edi
#define bufp_w %di
#define bufp_b %dil
@@ -105,9 +105,9 @@ SYM_FUNC_START(crc_pcl)
## 1) ALIGN:
################################################################
- mov bufp, bufptmp # rdi = *buf
- neg bufp
- and $7, bufp # calculate the unalignment amount of
+ mov %bufp, bufptmp # rdi = *buf
+ neg %bufp
+ and $7, %bufp # calculate the unalignment amount of
# the address
je proc_block # Skip if aligned
@@ -123,13 +123,13 @@ SYM_FUNC_START(crc_pcl)
do_align:
#### Calculate CRC of unaligned bytes of the buffer (if any)
movq (bufptmp), tmp # load a quadward from the buffer
- add bufp, bufptmp # align buffer pointer for quadword
+ add %bufp, bufptmp # align buffer pointer for quadword
# processing
- sub bufp, len # update buffer length
+ sub %bufp, len # update buffer length
align_loop:
crc32b %bl, crc_init_dw # compute crc32 of 1-byte
shr $8, tmp # get next byte
- dec bufp
+ dec %bufp
jne align_loop
proc_block:
@@ -169,10 +169,10 @@ continue_block:
xor crc2, crc2
## branch into array
- lea jump_table(%rip), bufp
- movzxw (bufp, %rax, 2), len
- lea crc_array(%rip), bufp
- lea (bufp, len, 1), bufp
+ lea jump_table(%rip), %bufp
+ movzxw (%bufp, %rax, 2), len
+ lea crc_array(%rip), %bufp
+ lea (%bufp, len, 1), %bufp
JMP_NOSPEC bufp
################################################################
@@ -218,9 +218,9 @@ LABEL crc_ %i
## 4) Combine three results:
################################################################
- lea (K_table-8)(%rip), bufp # first entry is for idx 1
+ lea (K_table-8)(%rip), %bufp # first entry is for idx 1
shlq $3, %rax # rax *= 8
- pmovzxdq (bufp,%rax), %xmm0 # 2 consts: K1:K2
+ pmovzxdq (%bufp,%rax), %xmm0 # 2 consts: K1:K2
leal (%eax,%eax,2), %eax # rax *= 3 (total *24)
subq %rax, tmp # tmp -= rax*24
diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S
index b67bae7091d7..7e7ffb7a5147 100644
--- a/arch/x86/entry/entry_32.S
+++ b/arch/x86/entry/entry_32.S
@@ -816,7 +816,7 @@ SYM_CODE_START(ret_from_fork)
/* kernel thread */
1: movl %edi, %eax
- CALL_NOSPEC %ebx
+ CALL_NOSPEC ebx
/*
* A kernel thread is allowed to return here after successfully
* calling do_execve(). Exit to userspace to complete the execve()
@@ -1501,7 +1501,7 @@ SYM_CODE_START_LOCAL_NOALIGN(common_exception_read_cr2)
TRACE_IRQS_OFF
movl %esp, %eax # pt_regs pointer
- CALL_NOSPEC %edi
+ CALL_NOSPEC edi
jmp ret_from_exception
SYM_CODE_END(common_exception_read_cr2)
@@ -1522,7 +1522,7 @@ SYM_CODE_START_LOCAL_NOALIGN(common_exception)
TRACE_IRQS_OFF
movl %esp, %eax # pt_regs pointer
- CALL_NOSPEC %edi
+ CALL_NOSPEC edi
jmp ret_from_exception
SYM_CODE_END(common_exception)
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 0e9504fabe52..168b798913bc 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -349,7 +349,7 @@ SYM_CODE_START(ret_from_fork)
/* kernel thread */
UNWIND_HINT_EMPTY
movq %r12, %rdi
- CALL_NOSPEC %rbx
+ CALL_NOSPEC rbx
/*
* A kernel thread is allowed to return here after successfully
* calling do_execve(). Exit to userspace to complete the execve()
diff --git a/arch/x86/include/asm/asm-prototypes.h b/arch/x86/include/asm/asm-prototypes.h
index ce92c4acc913..a75195f159cc 100644
--- a/arch/x86/include/asm/asm-prototypes.h
+++ b/arch/x86/include/asm/asm-prototypes.h
@@ -18,9 +18,13 @@ extern void cmpxchg8b_emu(void);
#ifdef CONFIG_RETPOLINE
#ifdef CONFIG_X86_32
-#define INDIRECT_THUNK(reg) extern asmlinkage void __x86_indirect_thunk_e ## reg(void);
+#define INDIRECT_THUNK(reg) \
+ extern asmlinkage void __x86_retpoline_e ## reg(void); \
+ extern asmlinkage void __x86_indirect_thunk_e ## reg(void);
#else
-#define INDIRECT_THUNK(reg) extern asmlinkage void __x86_indirect_thunk_r ## reg(void);
+#define INDIRECT_THUNK(reg) \
+ extern asmlinkage void __x86_retpoline_r ## reg(void); \
+ extern asmlinkage void __x86_indirect_thunk_r ## reg(void);
INDIRECT_THUNK(8)
INDIRECT_THUNK(9)
INDIRECT_THUNK(10)
diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h
index 07e95dcb40ad..0a3ceab5e0ec 100644
--- a/arch/x86/include/asm/nospec-branch.h
+++ b/arch/x86/include/asm/nospec-branch.h
@@ -76,34 +76,6 @@
.popsection
.endm
-/*
- * These are the bare retpoline primitives for indirect jmp and call.
- * Do not use these directly; they only exist to make the ALTERNATIVE
- * invocation below less ugly.
- */
-.macro RETPOLINE_JMP reg:req
- call .Ldo_rop_\@
-.Lspec_trap_\@:
- pause
- lfence
- jmp .Lspec_trap_\@
-.Ldo_rop_\@:
- mov \reg, (%_ASM_SP)
- ret
-.endm
-
-/*
- * This is a wrapper around RETPOLINE_JMP so the called function in reg
- * returns to the instruction after the macro.
- */
-.macro RETPOLINE_CALL reg:req
- jmp .Ldo_call_\@
-.Ldo_retpoline_jmp_\@:
- RETPOLINE_JMP \reg
-.Ldo_call_\@:
- call .Ldo_retpoline_jmp_\@
-.endm
-
/*
* JMP_NOSPEC and CALL_NOSPEC macros can be used instead of a simple
* indirect jmp/call which may be susceptible to the Spectre variant 2
@@ -111,10 +83,9 @@
*/
.macro JMP_NOSPEC reg:req
#ifdef CONFIG_RETPOLINE
- ANNOTATE_NOSPEC_ALTERNATIVE
- ALTERNATIVE_2 __stringify(ANNOTATE_RETPOLINE_SAFE; jmp *\reg), \
- __stringify(RETPOLINE_JMP \reg), X86_FEATURE_RETPOLINE, \
- __stringify(lfence; ANNOTATE_RETPOLINE_SAFE; jmp *\reg), X86_FEATURE_RETPOLINE_AMD
+ ALTERNATIVE_2 __stringify(ANNOTATE_RETPOLINE_SAFE; jmp *%\reg), \
+ __stringify(jmp __x86_retpoline_\()\reg), X86_FEATURE_RETPOLINE, \
+ __stringify(lfence; ANNOTATE_RETPOLINE_SAFE; jmp *%\reg), X86_FEATURE_RETPOLINE_AMD
#else
jmp *\reg
#endif
@@ -122,10 +93,9 @@
.macro CALL_NOSPEC reg:req
#ifdef CONFIG_RETPOLINE
- ANNOTATE_NOSPEC_ALTERNATIVE
- ALTERNATIVE_2 __stringify(ANNOTATE_RETPOLINE_SAFE; call *\reg), \
- __stringify(RETPOLINE_CALL \reg), X86_FEATURE_RETPOLINE,\
- __stringify(lfence; ANNOTATE_RETPOLINE_SAFE; call *\reg), X86_FEATURE_RETPOLINE_AMD
+ ALTERNATIVE_2 __stringify(ANNOTATE_RETPOLINE_SAFE; call *%\reg), \
+ __stringify(call __x86_retpoline_\()\reg), X86_FEATURE_RETPOLINE,\
+ __stringify(lfence; ANNOTATE_RETPOLINE_SAFE; call *%\reg), X86_FEATURE_RETPOLINE_AMD
#else
call *\reg
#endif
diff --git a/arch/x86/kernel/ftrace_32.S b/arch/x86/kernel/ftrace_32.S
index e8a9f8370112..e405fe1a8bf4 100644
--- a/arch/x86/kernel/ftrace_32.S
+++ b/arch/x86/kernel/ftrace_32.S
@@ -189,5 +189,5 @@ return_to_handler:
movl %eax, %ecx
popl %edx
popl %eax
- JMP_NOSPEC %ecx
+ JMP_NOSPEC ecx
#endif
diff --git a/arch/x86/kernel/ftrace_64.S b/arch/x86/kernel/ftrace_64.S
index 369e61faacfe..2f2b5702e6cf 100644
--- a/arch/x86/kernel/ftrace_64.S
+++ b/arch/x86/kernel/ftrace_64.S
@@ -303,7 +303,7 @@ trace:
* function tracing is enabled.
*/
movq ftrace_trace_function, %r8
- CALL_NOSPEC %r8
+ CALL_NOSPEC r8
restore_mcount_regs
jmp fgraph_trace
@@ -340,6 +340,6 @@ SYM_CODE_START(return_to_handler)
movq 8(%rsp), %rdx
movq (%rsp), %rax
addq $24, %rsp
- JMP_NOSPEC %rdi
+ JMP_NOSPEC rdi
SYM_CODE_END(return_to_handler)
#endif
diff --git a/arch/x86/lib/checksum_32.S b/arch/x86/lib/checksum_32.S
index 4742e8fa7ee7..d1d768912368 100644
--- a/arch/x86/lib/checksum_32.S
+++ b/arch/x86/lib/checksum_32.S
@@ -153,7 +153,7 @@ SYM_FUNC_START(csum_partial)
negl %ebx
lea 45f(%ebx,%ebx,2), %ebx
testl %esi, %esi
- JMP_NOSPEC %ebx
+ JMP_NOSPEC ebx
# Handle 2-byte-aligned regions
20: addw (%esi), %ax
@@ -436,7 +436,7 @@ SYM_FUNC_START(csum_partial_copy_generic)
andl $-32,%edx
lea 3f(%ebx,%ebx), %ebx
testl %esi, %esi
- JMP_NOSPEC %ebx
+ JMP_NOSPEC ebx
1: addl $64,%esi
addl $64,%edi
SRC(movb -32(%edx),%bl) ; SRC(movb (%edx),%bl)
diff --git a/arch/x86/lib/retpoline.S b/arch/x86/lib/retpoline.S
index 363ec132df7e..d4aef0c856a6 100644
--- a/arch/x86/lib/retpoline.S
+++ b/arch/x86/lib/retpoline.S
@@ -8,14 +8,31 @@
#include <asm/export.h>
#include <asm/nospec-branch.h>
+/*
+ * This is the bare retpoline primitive.
+ */
+.macro RETPOLINE_JMP reg:req
+ call .Ldo_rop_\@
+.Lspec_trap_\@:
+ pause
+ lfence
+ jmp .Lspec_trap_\@
+.Ldo_rop_\@:
+ mov \reg, (%_ASM_SP)
+ ret
+.endm
+
.macro THUNK reg
.section .text.__x86.indirect_thunk
+SYM_FUNC_START(__x86_retpoline_\reg)
+ RETPOLINE_JMP %\reg
+SYM_FUNC_END(__x86_retpoline_\reg)
+
SYM_FUNC_START(__x86_indirect_thunk_\reg)
- CFI_STARTPROC
- JMP_NOSPEC %\reg
- CFI_ENDPROC
+ JMP_NOSPEC \reg
SYM_FUNC_END(__x86_indirect_thunk_\reg)
+
.endm
/*
@@ -26,7 +43,9 @@ SYM_FUNC_END(__x86_indirect_thunk_\reg)
* the simple and nasty way...
*/
#define __EXPORT_THUNK(sym) _ASM_NOKPROBE(sym); EXPORT_SYMBOL(sym)
-#define EXPORT_THUNK(reg) __EXPORT_THUNK(__x86_indirect_thunk_ ## reg)
+#define EXPORT_THUNK(reg) \
+ __EXPORT_THUNK(__x86_retpoline_ ## reg); \
+ __EXPORT_THUNK(__x86_indirect_thunk_ ## reg)
#define GENERATE_THUNK(reg) THUNK reg ; EXPORT_THUNK(reg)
GENERATE_THUNK(_ASM_AX)
diff --git a/arch/x86/platform/efi/efi_stub_64.S b/arch/x86/platform/efi/efi_stub_64.S
index 15da118f04f0..90380a17ab23 100644
--- a/arch/x86/platform/efi/efi_stub_64.S
+++ b/arch/x86/platform/efi/efi_stub_64.S
@@ -21,7 +21,7 @@ SYM_FUNC_START(__efi_call)
mov %r8, %r9
mov %rcx, %r8
mov %rsi, %rcx
- CALL_NOSPEC %rdi
+ CALL_NOSPEC rdi
leave
ret
SYM_FUNC_END(__efi_call)
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