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[PATCH mig] Make MIG work for pure 64 bit kernel and userland (V2)
|
From: |
Flavio Cruz |
|
Subject: |
[PATCH mig] Make MIG work for pure 64 bit kernel and userland (V2) |
|
Date: |
Sun, 12 Feb 2023 12:49:44 -0500 |
Made changes to MIG so that generated stubs can be compiled when using
a 64 bit userland. The most important change here is to ensure
that data is always 8-byte aligned. Not doing that will lead to
undefined behavior since on 64 bits many structures can contain 64 bit
scalars which require 8-byte alignment. Even if x86 is usually fine with
unaligned accesses, compilers are taking advantage of this UD which may
break us in the future
(http://pzemtsov.github.io/2016/11/06/bug-story-alignment-on-x86.html)
The downside is that messages get significantly larger since we have
to pad the initial mach_msg_type_t so that the data item can be 8-byte
aligned. In the future, I want to make MIG layout the data in a way
that non-complex data can be packed together (essentially, how XNU messages
work) and to force userland to create larger structures so that we don't
have to do any structure resizing while in the kernel. For now, this unblocks
future work on 64 bits and is quite simple to understand.
For the 64 bit / 32 bit configuration, we can pass --enable-user32 when
targeting x86_64, and MIG will generate stubs as before. I am unsure
whether there exists undefined behavior in that particular configuration
since most of the structures used by the kernel do not seem to use 8
byte scalars so potentially we should be OK there.
As a follow up, we will need to change gnumach to iterate over these
messages correctly (to follow the 8-byte alignment rules).
Tested this patch by building Hurd and comparing previous stubs which
are byte-by-byte identical.
---
configure.ac | 7 ++++
cpu.sym | 4 +--
global.c | 5 +--
global.h | 5 +--
parser.y | 14 +++++---
routine.c | 5 ++-
server.c | 20 +++++------
type.c | 95 ++++++++++++++++++++++++++--------------------------
user.c | 22 ++++++------
utils.c | 6 +++-
utils.h | 2 ++
11 files changed, 105 insertions(+), 80 deletions(-)
diff --git a/configure.ac b/configure.ac
index e4645bd..8d52d5f 100644
--- a/configure.ac
+++ b/configure.ac
@@ -55,6 +55,13 @@ AC_SUBST([MIGCOM])
[MIG=`echo mig | sed "$program_transform_name"`]
AC_SUBST([MIG])
+AC_ARG_ENABLE(user32,
+ AS_HELP_STRING([--enable-user32],
+ [Build mig for 64 bit kernel that works with 32
bit userland]))
+AS_IF([test "x$enable_user32" = "xyes"], [
+ AC_DEFINE([USER32], [1], ["Build mig for 64 bit kernel that works with
32 bit userland"])
+])
+
AC_OUTPUT([Makefile mig tests/Makefile \
tests/good/Makefile \
tests/generate-only/Makefile \
diff --git a/cpu.sym b/cpu.sym
index 6bcb878..205ab3e 100644
--- a/cpu.sym
+++ b/cpu.sym
@@ -95,8 +95,8 @@ expr MACH_MSG_TYPE_POLYMORPHIC
/* Types used in interfaces */
-expr sizeof(integer_t) word_size
-expr (sizeof(integer_t)*8) word_size_in_bits
+/* The minimum alignment required for this architecture */
+expr sizeof(uintptr_t) desired_max_alignof
expr sizeof(void*) sizeof_pointer
expr sizeof(char) sizeof_char
expr sizeof(short) sizeof_short
diff --git a/global.c b/global.c
index bf3d10d..ad477c2 100644
--- a/global.c
+++ b/global.c
@@ -66,8 +66,9 @@ string_t InternalHeaderFileName = strNULL;
string_t UserFileName = strNULL;
string_t ServerFileName = strNULL;
-int port_size = port_name_size;
-int port_size_in_bits = port_name_size_in_bits;
+size_t port_size = port_name_size;
+size_t port_size_in_bits = port_name_size_in_bits;
+size_t max_alignof = desired_max_alignof;
void
more_global(void)
diff --git a/global.h b/global.h
index 8e57df2..bf8eb38 100644
--- a/global.h
+++ b/global.h
@@ -67,8 +67,9 @@ extern string_t InternalHeaderFileName;
extern string_t UserFileName;
extern string_t ServerFileName;
-extern int port_size;
-extern int port_size_in_bits;
+extern size_t port_size;
+extern size_t port_size_in_bits;
+extern size_t max_alignof;
extern void more_global(void);
diff --git a/parser.y b/parser.y
index 03c5ec8..3aa18c2 100644
--- a/parser.y
+++ b/parser.y
@@ -212,6 +212,16 @@ Subsystem : SubsystemStart SubsystemMods
IsKernelUser ? ", KernelUser" : "",
IsKernelServer ? ", KernelServer" : "");
}
+ if (IsKernelUser || IsKernelServer) {
+ port_size = vm_offset_size;
+ port_size_in_bits = vm_offset_size_in_bits;
+#ifdef USER32
+ /* Since we are using MIG to generate stubs for a 64 bit kernel that
operates
+ with a 32 bit userland, then we need to consider that `max_alignof`
is 4 byte aligned.
+ */
+ max_alignof = sizeof(uint32_t);
+#endif
+ }
init_type();
}
;
@@ -237,16 +247,12 @@ SubsystemMod : syKernelUser
if (IsKernelUser)
warn("duplicate KernelUser keyword");
IsKernelUser = true;
- port_size = vm_offset_size;
- port_size_in_bits = vm_offset_size_in_bits;
}
| syKernelServer
{
if (IsKernelServer)
warn("duplicate KernelServer keyword");
IsKernelServer = true;
- port_size = vm_offset_size;
- port_size_in_bits = vm_offset_size_in_bits;
}
;
diff --git a/routine.c b/routine.c
index c0a016c..5ed0064 100644
--- a/routine.c
+++ b/routine.c
@@ -47,6 +47,7 @@
#include "routine.h"
#include "message.h"
#include "cpu.h"
+#include "utils.h"
u_int rtNumber = 0;
@@ -316,19 +317,21 @@ rtFindSize(const argument_t *args, u_int mask)
const argument_t *arg;
u_int size = sizeof_mach_msg_header_t;
+ size = ALIGN(size, max_alignof);
for (arg = args; arg != argNULL; arg = arg->argNext)
if (akCheck(arg->argKind, mask))
{
ipc_type_t *it = arg->argType;
/* might need proper alignment on demanding 64bit archies */
- size = (size + word_size-1) & ~(word_size-1);
if (arg->argLongForm) {
size += sizeof_mach_msg_type_long_t;
} else {
size += sizeof_mach_msg_type_t;
}
+ size = ALIGN(size, max_alignof);
+ /* Note itMinTypeSize is already aligned to max_alignof. */
size += it->itMinTypeSize;
}
diff --git a/server.c b/server.c
index 95b0056..14b129b 100644
--- a/server.c
+++ b/server.c
@@ -483,7 +483,7 @@ WriteCheckArgSize(FILE *file, const argument_t *arg)
arg->argLongForm ? ".msgtl_header" : "");
}
- if (btype->itTypeSize % word_size != 0)
+ if (btype->itTypeSize % max_alignof != 0)
fprintf(file, "(");
if (multiplier > 1)
@@ -491,10 +491,10 @@ WriteCheckArgSize(FILE *file, const argument_t *arg)
fprintf(file, "In%dP->%s", arg->argRequestPos, count->argMsgField);
- /* If the base type size of the data field isn`t a multiple of word_size,
+ /* If the base type size of the data field isn`t a multiple of max_alignof,
we have to round up. */
- if (btype->itTypeSize % word_size != 0)
- fprintf(file, " + %d) & ~%d", word_size - 1, word_size - 1);
+ if (btype->itTypeSize % max_alignof != 0)
+ fprintf(file, " + %d) & ~%d", max_alignof - 1, max_alignof - 1);
if (ptype->itIndefinite) {
fprintf(file, " : sizeof(%s *)", FetchServerType(btype));
@@ -530,8 +530,8 @@ WriteCheckMsgSize(FILE *file, const argument_t *arg)
bool LastVarArg = arg->argRequestPos+1 == rt->rtNumRequestVar;
/* calculate the actual size in bytes of the data field. note
- that this quantity must be a multiple of word_size. hence, if
- the base type size isn't a multiple of word_size, we have to
+ that this quantity must be a multiple of max_alignof. hence, if
+ the base type size isn't a multiple of max_alignof, we have to
round up. note also that btype->itNumber must
divide btype->itTypeSize (see itCalculateSizeInfo). */
@@ -1090,7 +1090,7 @@ WriteArgSize(FILE *file, const argument_t *arg)
arg->argLongForm ? ".msgtl_header" : "");
}
- if (bsize % word_size != 0)
+ if (bsize % max_alignof != 0)
fprintf(file, "(");
if (bsize > 1)
@@ -1103,11 +1103,11 @@ WriteArgSize(FILE *file, const argument_t *arg)
fprintf(file, "%s", count->argVarName);
/*
- * If the base type size is not a multiple of word_size,
+ * If the base type size is not a multiple of max_alignof,
* we have to round up.
*/
- if (bsize % word_size != 0)
- fprintf(file, " + %d) & ~%d", word_size - 1, word_size - 1);
+ if (bsize % max_alignof != 0)
+ fprintf(file, " + %d) & ~%d", max_alignof - 1, max_alignof - 1);
if (ptype->itIndefinite) {
fprintf(file, " : sizeof(%s *)",
diff --git a/type.c b/type.c
index b104c66..f44be57 100644
--- a/type.c
+++ b/type.c
@@ -35,17 +35,8 @@
#include "cpu.h"
#include "utils.h"
-#if word_size_in_bits == 32
-#define word_size_name MACH_MSG_TYPE_INTEGER_32
-#define word_size_name_string "MACH_MSG_TYPE_INTEGER_32"
-#else
-#if word_size_in_bits == 64
-#define word_size_name MACH_MSG_TYPE_INTEGER_64
-#define word_size_name_string "MACH_MSG_TYPE_INTEGER_64"
-#else
-#error Unsupported word size!
-#endif
-#endif
+#define int_name MACH_MSG_TYPE_INTEGER_32
+#define int_name_string "MACH_MSG_TYPE_INTEGER_32"
ipc_type_t *itByteType; /* used for defining struct types */
ipc_type_t *itRetCodeType; /* used for return codes */
@@ -169,10 +160,12 @@ itNameToString(u_int name)
static void
itCalculateSizeInfo(ipc_type_t *it)
{
+ assert(it->itAlignment > 0);
+
if (it->itInLine)
{
u_int bytes = (it->itNumber * it->itSize + 7) / 8;
- u_int padding = (word_size - bytes % word_size) % word_size;
+ u_int padding = (max_alignof - bytes % max_alignof) % max_alignof;
it->itTypeSize = bytes;
it->itPadSize = padding;
@@ -189,7 +182,7 @@ itCalculateSizeInfo(ipc_type_t *it)
it->itTypeSize = bytes;
it->itPadSize = 0;
it->itMinTypeSize = bytes;
- it->itAlignment = bytes;
+ assert(it->itAlignment == bytes);
}
/* Unfortunately, these warning messages can't give a type name;
@@ -542,7 +535,7 @@ itLongDecl(u_int inname, const_string_t instr, u_int
outname,
it->itOutName = outname;
it->itOutNameStr = outstr;
it->itSize = size;
- it->itAlignment = MIN(word_size, size / 8);
+ it->itAlignment = MIN(max_alignof, size / 8);
if (inname == MACH_MSG_TYPE_STRING_C)
{
it->itStruct = false;
@@ -682,6 +675,7 @@ itPtrDecl(ipc_type_t *it)
it->itInLine = false;
it->itStruct = true;
it->itString = false;
+ it->itAlignment = sizeof_pointer;
itCalculateSizeInfo(it);
return it;
@@ -806,7 +800,6 @@ itCIntTypeDecl(const_string_t ctype, const size_t size)
exit(EXIT_FAILURE);
}
it->itName = ctype;
- it->itAlignment = size;
itCalculateNameInfo(it);
return it;
}
@@ -817,11 +810,12 @@ itMakeCountType(void)
ipc_type_t *it = itAlloc();
it->itName = "mach_msg_type_number_t";
- it->itInName = word_size_name;
- it->itInNameStr = word_size_name_string;
- it->itOutName = word_size_name;
- it->itOutNameStr = word_size_name_string;
- it->itSize = word_size_in_bits;
+ it->itInName = int_name;
+ it->itInNameStr = int_name_string;
+ it->itOutName = int_name;
+ it->itOutNameStr = int_name_string;
+ it->itSize = sizeof_int * 8;
+ it->itAlignment = sizeof_int;
itCalculateSizeInfo(it);
itCalculateNameInfo(it);
@@ -834,11 +828,12 @@ itMakeNaturalType(const char *name)
ipc_type_t *it = itAlloc();
it->itName = name;
- it->itInName = word_size_name;
- it->itInNameStr = word_size_name_string;
- it->itOutName = word_size_name;
- it->itOutNameStr = word_size_name_string;
- it->itSize = word_size_in_bits;
+ it->itInName = int_name;
+ it->itInNameStr = int_name_string;
+ it->itOutName = int_name;
+ it->itOutNameStr = int_name_string;
+ it->itSize = sizeof_int * 8;
+ it->itAlignment = sizeof_int;
itCalculateSizeInfo(it);
itCalculateNameInfo(it);
@@ -851,11 +846,12 @@ itMakePolyType(void)
ipc_type_t *it = itAlloc();
it->itName = "mach_msg_type_name_t";
- it->itInName = word_size_name;
- it->itInNameStr = word_size_name_string;
- it->itOutName = word_size_name;
- it->itOutNameStr = word_size_name_string;
- it->itSize = word_size_in_bits;
+ it->itInName = int_name;
+ it->itInNameStr = int_name_string;
+ it->itOutName = int_name;
+ it->itOutNameStr = int_name_string;
+ it->itSize = sizeof_int * 8;
+ it->itAlignment = sizeof_int;
itCalculateSizeInfo(it);
itCalculateNameInfo(it);
@@ -872,7 +868,8 @@ itMakeDeallocType(void)
it->itInNameStr = "MACH_MSG_TYPE_BOOLEAN";
it->itOutName = MACH_MSG_TYPE_BOOLEAN;
it->itOutNameStr = "MACH_MSG_TYPE_BOOLEAN";
- it->itSize = 32;
+ it->itSize = sizeof_int * 8;
+ it->itAlignment = sizeof_int;
itCalculateSizeInfo(it);
itCalculateNameInfo(it);
@@ -899,17 +896,19 @@ init_type(void)
itByteType->itInNameStr = "MACH_MSG_TYPE_BYTE";
itByteType->itOutName = MACH_MSG_TYPE_BYTE;
itByteType->itOutNameStr = "MACH_MSG_TYPE_BYTE";
- itByteType->itSize = 8;
+ itByteType->itSize = sizeof_char * 8;
+ itByteType->itAlignment = sizeof_char;
itCalculateSizeInfo(itByteType);
itCalculateNameInfo(itByteType);
itRetCodeType = itAlloc();
itRetCodeType->itName = "kern_return_t";
- itRetCodeType->itInName = MACH_MSG_TYPE_INTEGER_32;
- itRetCodeType->itInNameStr = "MACH_MSG_TYPE_INTEGER_32";
- itRetCodeType->itOutName = MACH_MSG_TYPE_INTEGER_32;
- itRetCodeType->itOutNameStr = "MACH_MSG_TYPE_INTEGER_32";
- itRetCodeType->itSize = 32;
+ itRetCodeType->itInName = int_name;
+ itRetCodeType->itInNameStr = int_name_string;
+ itRetCodeType->itOutName = int_name;
+ itRetCodeType->itOutNameStr = int_name_string;
+ itRetCodeType->itSize = sizeof_int * 8;
+ itRetCodeType->itAlignment = sizeof_int;
itCalculateSizeInfo(itRetCodeType);
itCalculateNameInfo(itRetCodeType);
@@ -919,7 +918,8 @@ init_type(void)
itDummyType->itInNameStr = "MACH_MSG_TYPE_UNSTRUCTURED";
itDummyType->itOutName = MACH_MSG_TYPE_UNSTRUCTURED;
itDummyType->itOutNameStr = "MACH_MSG_TYPE_UNSTRUCTURED";
- itDummyType->itSize = word_size_in_bits;
+ itDummyType->itSize = max_alignof * 8;
+ itDummyType->itAlignment = max_alignof;
itCalculateSizeInfo(itDummyType);
itCalculateNameInfo(itDummyType);
@@ -930,6 +930,7 @@ init_type(void)
itRequestPortType->itOutName = MACH_MSG_TYPE_PORT_SEND;
itRequestPortType->itOutNameStr = "MACH_MSG_TYPE_PORT_SEND";
itRequestPortType->itSize = port_size_in_bits;
+ itRequestPortType->itAlignment = port_size;
itCalculateSizeInfo(itRequestPortType);
itCalculateNameInfo(itRequestPortType);
@@ -940,6 +941,7 @@ init_type(void)
itZeroReplyPortType->itOutName = 0;
itZeroReplyPortType->itOutNameStr = "0";
itZeroReplyPortType->itSize = port_size_in_bits;
+ itZeroReplyPortType->itAlignment = port_size;
itCalculateSizeInfo(itZeroReplyPortType);
itCalculateNameInfo(itZeroReplyPortType);
@@ -950,6 +952,7 @@ init_type(void)
itRealReplyPortType->itOutName = MACH_MSG_TYPE_PORT_SEND_ONCE;
itRealReplyPortType->itOutNameStr = "MACH_MSG_TYPE_PORT_SEND_ONCE";
itRealReplyPortType->itSize = port_size_in_bits;
+ itRealReplyPortType->itAlignment = port_size;
itCalculateSizeInfo(itRealReplyPortType);
itCalculateNameInfo(itRealReplyPortType);
@@ -1030,8 +1033,8 @@ itCheckReplyPortType(identifier_t name, const ipc_type_t
*it)
void
itCheckIntType(identifier_t name, const ipc_type_t *it)
{
- if ((it->itInName != MACH_MSG_TYPE_INTEGER_32) ||
- (it->itOutName != MACH_MSG_TYPE_INTEGER_32) ||
+ if ((it->itInName != int_name) ||
+ (it->itOutName != int_name) ||
(it->itNumber != 1) ||
(it->itSize != 32) ||
!it->itInLine ||
@@ -1041,17 +1044,15 @@ itCheckIntType(identifier_t name, const ipc_type_t *it)
error("argument %s isn't a proper integer", name);
}
void
-itCheckNaturalType(name, it)
- identifier_t name;
- ipc_type_t *it;
+itCheckNaturalType(identifier_t name, ipc_type_t *it)
{
- if ((it->itInName != word_size_name) ||
- (it->itOutName != word_size_name) ||
+ if ((it->itInName != int_name) ||
+ (it->itOutName != int_name) ||
(it->itNumber != 1) ||
- (it->itSize != word_size_in_bits) ||
+ (it->itSize != sizeof_int * 8) ||
!it->itInLine ||
it->itDeallocate != d_NO ||
!it->itStruct ||
it->itVarArray)
- error("argument %s should have been a %s", name, word_size_name_string);
+ error("argument %s should have been a %s", name, int_name_string);
}
diff --git a/user.c b/user.c
index e951ee2..dd43335 100644
--- a/user.c
+++ b/user.c
@@ -507,7 +507,7 @@ WriteArgSize(FILE *file, const argument_t *arg)
fprintf(file, "(InP->%s%s.msgt_inline) ? ",
arg->argTTName, arg->argLongForm ? ".msgtl_header" : "");
}
- if (bsize % word_size != 0)
+ if (bsize % max_alignof != 0)
fprintf(file, "(");
if (bsize > 1)
@@ -523,11 +523,11 @@ WriteArgSize(FILE *file, const argument_t *arg)
count->argVarName);
/*
- * If the base type size is not a multiple of word_size,
+ * If the base type size is not a multiple of max_alignof,
* we have to round up.
*/
- if (bsize % word_size != 0)
- fprintf(file, " + %d) & ~%d", word_size - 1, word_size - 1);
+ if (bsize % max_alignof != 0)
+ fprintf(file, " + %d) & ~%d", max_alignof - 1, max_alignof - 1);
if (ptype->itIndefinite) {
fprintf(file, " : sizeof(%s *)",
@@ -831,7 +831,7 @@ WriteCheckArgSize(FILE *file, const argument_t *arg)
arg->argTTName, arg->argLongForm ? ".msgtl_header" : "");
}
- if (btype->itTypeSize % word_size != 0)
+ if (btype->itTypeSize % max_alignof != 0)
fprintf(file, "(");
if (multiplier > 1)
@@ -839,10 +839,10 @@ WriteCheckArgSize(FILE *file, const argument_t *arg)
fprintf(file, "OutP->%s", count->argMsgField);
- /* If the base type size of the data field isn`t a multiple of word_size,
+ /* If the base type size of the data field isn`t a multiple of max_alignof,
we have to round up. */
- if (btype->itTypeSize % word_size != 0)
- fprintf(file, " + %d) & ~%d", word_size - 1, word_size - 1);
+ if (btype->itTypeSize % max_alignof != 0)
+ fprintf(file, " + %d) & ~%d", max_alignof - 1, max_alignof - 1);
if (ptype->itIndefinite)
fprintf(file, " : sizeof(%s *)", FetchUserType(btype));
@@ -877,8 +877,8 @@ WriteCheckMsgSize(FILE *file, const argument_t *arg)
bool LastVarArg = arg->argReplyPos+1 == rt->rtNumReplyVar;
/* calculate the actual size in bytes of the data field. note
- that this quantity must be a multiple of word_size. hence, if
- the base type size isn't a multiple of word_size, we have to
+ that this quantity must be a multiple of max_alignof. hence, if
+ the base type size isn't a multiple of max_alignof, we have to
round up. note also that btype->itNumber must
divide btype->itTypeSize (see itCalculateSizeInfo). */
@@ -1127,7 +1127,7 @@ WriteReturnValue(FILE *file, const routine_t *rt)
/*************************************************************
* Writes the elements of the message type declaration: the
* msg_type structure, the argument itself and any padding
- * that is required to make the argument a multiple of word_size bytes.
+ * that is required to make the argument a multiple of max_alignof bytes.
* Called by WriteRoutine for all the arguments in the request
* message first and then the reply message.
*************************************************************/
diff --git a/utils.c b/utils.c
index 2fb8c2e..b65e304 100644
--- a/utils.c
+++ b/utils.c
@@ -304,6 +304,10 @@ WriteFieldDeclPrim(FILE *file, const argument_t *arg,
fprintf(file, "\t\tmach_msg_type_%st %s;\n",
arg->argLongForm ? "long_" : "", arg->argTTName);
+ if (!arg->argLongForm && max_alignof > sizeof_mach_msg_type_t) {
+ /* Pad mach_msg_type_t in case we need alignment by more than its
size. */
+ fprintf(file, "\t\tchar %s_pad[%d];\n", arg->argTTName, max_alignof -
sizeof_mach_msg_type_t);
+ }
if (it->itInLine && it->itVarArray)
{
@@ -338,7 +342,7 @@ void
WriteStructDecl(FILE *file, const argument_t *args, write_list_fn_t *func,
u_int mask, const char *name)
{
- fprintf(file, "#pragma pack(push,%d)\n", word_size);
+ fprintf(file, "#pragma pack(push,%d)\n", max_alignof);
fprintf(file, "\ttypedef struct {\n");
fprintf(file, "\t\tmach_msg_header_t Head;\n");
WriteList(file, args, func, mask, "\n", "\n");
diff --git a/utils.h b/utils.h
index 4be4f4c..477ea74 100644
--- a/utils.h
+++ b/utils.h
@@ -39,6 +39,8 @@
({ __typeof__ (a) _a = (a); \
__typeof__ (b) _b = (b); \
_a > _b ? _b : _a; })
+#define ALIGN(x, alignment) \
+ ((x) + (alignment)-1) & ~((alignment)-1)
typedef void write_list_fn_t(FILE *file, const argument_t *arg);
--
2.39.1
- [PATCH mig] Make MIG work for pure 64 bit kernel and userland (V2),
Flavio Cruz <=