Add CODEPATCH_CODE() macro to simplify defining a symbol for a chunk

of code to use in codepatching.  Use that for all the existing
codepatching snippets.

Similarly, add CODEPATCH_CODE_LEN() which is CODEPATCH_CODE() but also
provides a short variable holding the length of the codepatch snippet.
Use that for some snippets that will be used for retpoline replacement.

ok kettenis@ deraadt@

diff --git a/sys/arch/amd64/amd64/copy.S b/sys/arch/amd64/amd64/copy.S
index ae254bf..f09ebf9 100644 (file)
--- a/sys/arch/amd64/amd64/copy.S
+++ b/sys/arch/amd64/amd64/copy.S
@@ -1,4 +1,4 @@
-/*     $OpenBSD: copy.S,v 1.18 2023/01/31 15:18:54 deraadt Exp $       */
+/*     $OpenBSD: copy.S,v 1.19 2023/07/28 06:18:35 guenther Exp $      */
 /*     $NetBSD: copy.S,v 1.1 2003/04/26 18:39:26 fvdl Exp $    */
 
 /*
@@ -299,11 +299,5 @@ copystr_return:
        ret
        lfence
 
-       .section .rodata
-       .globl  _stac
-_stac:
-       stac
-
-       .globl  _clac
-_clac:
-       clac
+CODEPATCH_CODE(_stac,  stac)
+CODEPATCH_CODE(_clac,  clac)

diff --git a/sys/arch/amd64/amd64/locore.S b/sys/arch/amd64/amd64/locore.S
index 2046f09..9024948 100644 (file)
--- a/sys/arch/amd64/amd64/locore.S
+++ b/sys/arch/amd64/amd64/locore.S
@@ -1,4 +1,4 @@
-/*     $OpenBSD: locore.S,v 1.138 2023/07/27 00:28:24 guenther Exp $   */
+/*     $OpenBSD: locore.S,v 1.139 2023/07/28 06:18:35 guenther Exp $   */
 /*     $NetBSD: locore.S,v 1.13 2004/03/25 18:33:17 drochner Exp $     */
 
 /*
@@ -1084,30 +1084,16 @@ NENTRY(xsetbv_resume)
        lfence
 END(xsetbv_user)
 
-       .section .rodata
-       .globl  _xrstor
-_xrstor:
-       xrstor64        (%rdi)
-
-       .globl  _xrstors
-_xrstors:
-       xrstors64       (%rdi)
-
-       .globl  _xsave
-_xsave:
-       xsave64         (%rdi)
-
-       .globl  _xsaves
-_xsaves:
-       xsaves64        (%rdi)
-
-       .globl  _xsaveopt
-_xsaveopt:
-       xsaveopt64      (%rdi)
-
-       .globl  _pcid_set_reuse
-_pcid_set_reuse:
-       orl     $(CR3_REUSE_PCID >> 32),CPUVAR(USER_CR3 + 4)
+CODEPATCH_CODE(_xrstor,                xrstor64 (%rdi))
+CODEPATCH_CODE(_xrstors,       xrstors64 (%rdi))
+CODEPATCH_CODE(_xsave,         xsave64 (%rdi))
+CODEPATCH_CODE(_xsaves,                xsaves64 (%rdi))
+CODEPATCH_CODE(_xsaveopt,      xsaveopt64 (%rdi))
+CODEPATCH_CODE(_pcid_set_reuse,
+               orl     $(CR3_REUSE_PCID >> 32),CPUVAR(USER_CR3 + 4))
+CODEPATCH_CODE_LEN(_jmprax,    jmp *%rax; int3)
+CODEPATCH_CODE_LEN(_jmpr11,    jmp *%r11; int3)
+CODEPATCH_CODE_LEN(_jmpr13,    jmp *%r13; int3)
 
 ENTRY(pagezero)
        RETGUARD_SETUP(pagezero, r11)

diff --git a/sys/arch/amd64/include/codepatch.h b/sys/arch/amd64/include/codepatch.h
index 50618bd..71fe947 100644 (file)
--- a/sys/arch/amd64/include/codepatch.h
+++ b/sys/arch/amd64/include/codepatch.h
@@ -1,4 +1,4 @@
-/*      $OpenBSD: codepatch.h,v 1.15 2023/07/10 03:32:10 guenther Exp $    */
+/*      $OpenBSD: codepatch.h,v 1.16 2023/07/28 06:18:35 guenther Exp $    */
 /*
  * Copyright (c) 2014-2015 Stefan Fritsch <sf@sfritsch.de>
  *
@@ -97,4 +97,20 @@ void codepatch_disable(void);
        .byte   0x0f, 0x1f, 0x40, 0x00                          ;\
        CODEPATCH_END2(997, CPTAG_PCID_SET_REUSE)
 
+/* Would be neat if these could be in something like .cptext */
+#define CODEPATCH_CODE(symbol, instructions...)                \
+       .section .rodata;                               \
+       .globl  symbol;                                 \
+symbol:        instructions;                                   \
+       .size   symbol, . - symbol
+
+/* provide a (short) variable with the length of the patch */
+#define CODEPATCH_CODE_LEN(symbol, instructions...)    \
+       CODEPATCH_CODE(symbol, instructions);           \
+996:   .globl  symbol##_len;                           \
+       .align  2;                                      \
+symbol##_len:                                          \
+       .short  996b - symbol;                          \
+       .size   symbol##_len, 2
+
 #endif /* _MACHINE_CODEPATCH_H_ */