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Automate the handling of QUAD_ALIGN and QUAD_SLOTS.

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Previously, the offset in a system call description specified the
array index of the start of a system call argument.  For most system
call arguments this was the same as the index of the argument in the
function signature.  64-bit arguments (off_t and id_t values) passed
on 32-bit platforms use two slots in the array however.  This was
handled by adding (QUAD_SLOTS - 1) to the slot indicies of any
subsequent arguments after a 64-bit argument (though written as ("{
Quad, 1 }, { Int, 1 + QUAD_SLOTS }" rather than "{ Quad, 1 }, { Int, 2
+ QUAD_SLOTS - 1 }").  If a system call contained multiple 64-bit
arguments (such as posix_fadvise()), then additional arguments would
need to use 'QUAD_SLOTS * 2' but remember to subtract 2 from the
initial number, etc.  In addition, 32-bit powerpc requires 64-bit
arguments to be 64-bit aligned, so if the effective index in the array
of a 64-bit argument is odd, it needs QUAD_ALIGN added to the current
and any subsequent slots.  However, if the effective index in the
array of a 64-bit argument was even, QUAD_ALIGN was omitted.

This approach was messy and error prone.  This commit replaces it with
automated pre-processing of the system call table to do fixups for
64-bit argument offsets.  The offset in a system call description now
indicates the index of an argument in the associated function call's
signature.  A fixup function is run against each decoded system call
description during startup on 32-bit platforms.  The fixup function
maintains an 'offset' value which holds an offset to be added to each
remaining system call argument's index.  Initially offset is 0.  When
a 64-bit system call argument is encountered, the offset is first
aligned to a 64-bit boundary (only on powerpc) and then incremented to
account for the second argument slot used by the argument.  This
modified 'offset' is then applied to any remaining arguments.  This
approach does require a few things that were not previously required:

1) Each system call description must now list arguments in ascending
   order (existing ones all do) without using duplicate slots in the
   register array.  A new assert() should catch any future
   descriptions which violate this rule.

2) A system call description is still permitted to omit arguments
   (though none currently do), but if the call accepts 64-bit
   arguments those cannot be omitted or incorrect results will be
   displated on 32-bit systems.

Tested on:	amd64 and i386
This commit is contained in:
John Baldwin 2017-03-15 23:08:11 +00:00
parent 64f4703b9b
commit c05cc0d6c8
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=315336
1 changed files with 59 additions and 28 deletions
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87
usr.bin/truss/syscalls.c
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@ -71,20 +71,6 @@ __FBSDID("$FreeBSD$");
#include "extern.h"
#include "syscall.h"
/* 64-bit alignment on 32-bit platforms. */
#if !defined(__LP64__) && defined(__powerpc__)
#define QUAD_ALIGN 1
#else
#define QUAD_ALIGN 0
#endif
/* Number of slots needed for a 64-bit argument. */
#ifdef __LP64__
#define QUAD_SLOTS 1
#else
#define QUAD_SLOTS 2
#endif
/*
* This should probably be in its own file, sorted alphabetically.
*/
@ -154,7 +140,7 @@ static struct syscall decoded_syscalls[] = {
{ .name = "fstatfs", .ret_type = 1, .nargs = 2,
.args = { { Int, 0 }, { StatFs | OUT, 1 } } },
{ .name = "ftruncate", .ret_type = 1, .nargs = 2,
.args = { { Int | IN, 0 }, { QuadHex | IN, 1 + QUAD_ALIGN } } },
.args = { { Int | IN, 0 }, { QuadHex | IN, 1 } } },
{ .name = "futimens", .ret_type = 1, .nargs = 2,
.args = { { Int, 0 }, { Timespec2 | IN, 1 } } },
{ .name = "futimes", .ret_type = 1, .nargs = 2,
@ -210,8 +196,7 @@ static struct syscall decoded_syscalls[] = {
.args = { { Atfd, 0 }, { Name, 1 }, { Atfd, 2 }, { Name, 3 },
{ Atflags, 4 } } },
{ .name = "lseek", .ret_type = 2, .nargs = 3,
.args = { { Int, 0 }, { QuadHex, 1 + QUAD_ALIGN },
{ Whence, 1 + QUAD_SLOTS + QUAD_ALIGN } } },
.args = { { Int, 0 }, { QuadHex, 1 }, { Whence, 2 } } },
{ .name = "lstat", .ret_type = 1, .nargs = 2,
.args = { { Name | IN, 0 }, { Stat | OUT, 1 } } },
{ .name = "lutimes", .ret_type = 1, .nargs = 2,
@ -230,7 +215,7 @@ static struct syscall decoded_syscalls[] = {
.args = { { Atfd, 0 }, { Name, 1 }, { Octal, 2 }, { Int, 3 } } },
{ .name = "mmap", .ret_type = 1, .nargs = 6,
.args = { { Ptr, 0 }, { Int, 1 }, { Mprot, 2 }, { Mmapflags, 3 },
{ Int, 4 }, { QuadHex, 5 + QUAD_ALIGN } } },
{ Int, 4 }, { QuadHex, 5 } } },
{ .name = "modfind", .ret_type = 1, .nargs = 1,
.args = { { Name | IN, 0 } } },
{ .name = "mount", .ret_type = 1, .nargs = 4,
@ -257,9 +242,7 @@ static struct syscall decoded_syscalls[] = {
{ .name = "posix_openpt", .ret_type = 1, .nargs = 1,
.args = { { Open, 0 } } },
{ .name = "procctl", .ret_type = 1, .nargs = 4,
.args = { { Idtype, 0 }, { Quad, 1 + QUAD_ALIGN },
{ Procctl, 1 + QUAD_ALIGN + QUAD_SLOTS },
{ Ptr, 2 + QUAD_ALIGN + QUAD_SLOTS } } },
.args = { { Idtype, 0 }, { Quad, 1 }, { Procctl, 2 }, { Ptr, 3 } } },
{ .name = "read", .ret_type = 1, .nargs = 3,
.args = { { Int, 0 }, { BinString | OUT, 1 }, { Int, 2 } } },
{ .name = "readlink", .ret_type = 1, .nargs = 3,
@ -326,7 +309,7 @@ static struct syscall decoded_syscalls[] = {
{ .name = "thr_self", .ret_type = 1, .nargs = 1,
.args = { { Ptr, 0 } } },
{ .name = "truncate", .ret_type = 1, .nargs = 2,
.args = { { Name | IN, 0 }, { QuadHex | IN, 1 + QUAD_ALIGN } } },
.args = { { Name | IN, 0 }, { QuadHex | IN, 1 } } },
#if 0
/* Does not exist */
{ .name = "umount", .ret_type = 1, .nargs = 2,
@ -349,11 +332,8 @@ static struct syscall decoded_syscalls[] = {
.args = { { Int, 0 }, { ExitStatus | OUT, 1 }, { Waitoptions, 2 },
{ Rusage | OUT, 3 } } },
{ .name = "wait6", .ret_type = 1, .nargs = 6,
.args = { { Idtype, 0 }, { Quad, 1 + QUAD_ALIGN },
{ ExitStatus | OUT, 1 + QUAD_ALIGN + QUAD_SLOTS },
{ Waitoptions, 2 + QUAD_ALIGN + QUAD_SLOTS },
{ Rusage | OUT, 3 + QUAD_ALIGN + QUAD_SLOTS },
{ Ptr, 4 + QUAD_ALIGN + QUAD_SLOTS } } },
.args = { { Idtype, 0 }, { Quad, 1 }, { ExitStatus | OUT, 2 },
{ Waitoptions, 3 }, { Rusage | OUT, 4 }, { Ptr, 5 } } },
{ .name = "write", .ret_type = 1, .nargs = 3,
.args = { { Int, 0 }, { BinString | IN, 1 }, { Int, 2 } } },
@ -811,14 +791,65 @@ print_mask_arg(bool (*decoder)(FILE *, int, int *), FILE *fp, int value)
fprintf(fp, "|0x%x", rem);
}
#ifndef __LP64__
/*
* Add argument padding to subsequent system calls afater a Quad
* syscall arguments as needed. This used to be done by hand in the
* decoded_syscalls table which was ugly and error prone. It is
* simpler to do the fixup of offsets at initalization time than when
* decoding arguments.
*/
static void
quad_fixup(struct syscall *sc)
{
int offset, prev;
u_int i;
offset = 0;
prev = -1;
for (i = 0; i < sc->nargs; i++) {
/* This arg type is a dummy that doesn't use offset. */
if ((sc->args[i].type & ARG_MASK) == PipeFds)
continue;
assert(prev < sc->args[i].offset);
prev = sc->args[i].offset;
sc->args[i].offset += offset;
switch (sc->args[i].type & ARG_MASK) {
case Quad:
case QuadHex:
#ifdef __powerpc__
/*
* 64-bit arguments on 32-bit powerpc must be
* 64-bit aligned. If the current offset is
* not aligned, the calling convention inserts
* a 32-bit pad argument that should be skipped.
*/
if (sc->args[i].offset % 2 == 1) {
sc->args[i].offset++;
offset++;
}
#endif
offset++;
default:
break;
}
}
}
#endif
void
init_syscalls(void)
{
struct syscall *sc;
STAILQ_INIT(&syscalls);
for (sc = decoded_syscalls; sc->name != NULL; sc++)
for (sc = decoded_syscalls; sc->name != NULL; sc++) {
#ifndef __LP64__
quad_fixup(sc);
#endif
STAILQ_INSERT_HEAD(&syscalls, sc, entries);
}
}
static struct syscall *