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[PULL 05/10] bsd-user: Helper routines oidfmt
From: |
Warner Losh |
Subject: |
[PULL 05/10] bsd-user: Helper routines oidfmt |
Date: |
Wed, 1 Mar 2023 11:23:48 -0700 |
From: Stacey Son <sson@FreeBSD.org>
oidfmt uses undocumented system call to get the type of the sysctl.
Co-Authored-by: Sean Bruno <sbruno@FreeBSD.org>
Signed-off-by: Sean Bruno <sbruno@FreeBSD.org>
Co-Authored-by: Juergen Lock <nox@jelal.kn-bremen.de>
Signed-off-by: Juergen Lock <nox@jelal.kn-bremen.de>
Co-Authored-by: Raphael Kubo da Costa <rakuco@FreeBSD.org>
Signed-off-by: Raphael Kubo da Costa <rakuco@FreeBSD.org>
Signed-off-by: Stacey Son <sson@FreeBSD.org>
Reviewed-by: Warner Losh <imp@bsdimp.com>
Signed-off-by: Warner Losh <imp@bsdimp.com>
Acked-by: Richard Henderson <richard.henderson@linaro.org>
---
bsd-user/freebsd/os-sys.c | 131 ++++++++++++++++++++++++++++++++++++--
1 file changed, 127 insertions(+), 4 deletions(-)
diff --git a/bsd-user/freebsd/os-sys.c b/bsd-user/freebsd/os-sys.c
index a4f3fd8091a..2e0a6c058d6 100644
--- a/bsd-user/freebsd/os-sys.c
+++ b/bsd-user/freebsd/os-sys.c
@@ -29,7 +29,7 @@
* Compare with sys/kern_sysctl.c ctl_size
* Note: Not all types appear to be used in-tree.
*/
-static const int G_GNUC_UNUSED guest_ctl_size[CTLTYPE + 1] = {
+static const int guest_ctl_size[CTLTYPE + 1] = {
[CTLTYPE_INT] = sizeof(abi_int),
[CTLTYPE_UINT] = sizeof(abi_uint),
[CTLTYPE_LONG] = sizeof(abi_long),
@@ -44,7 +44,7 @@ static const int G_GNUC_UNUSED guest_ctl_size[CTLTYPE + 1] = {
[CTLTYPE_U64] = sizeof(uint64_t),
};
-static const int G_GNUC_UNUSED host_ctl_size[CTLTYPE + 1] = {
+static const int host_ctl_size[CTLTYPE + 1] = {
[CTLTYPE_INT] = sizeof(int),
[CTLTYPE_UINT] = sizeof(u_int),
[CTLTYPE_LONG] = sizeof(long),
@@ -86,7 +86,7 @@ static abi_ulong G_GNUC_UNUSED scale_to_guest_pages(uint64_t
pages)
#ifdef TARGET_ABI32
/* Used only for TARGET_ABI32 */
-static abi_long G_GNUC_UNUSED h2g_long_sat(long l)
+static abi_long h2g_long_sat(long l)
{
if (l > INT32_MAX) {
l = INT32_MAX;
@@ -96,7 +96,7 @@ static abi_long G_GNUC_UNUSED h2g_long_sat(long l)
return l;
}
-static abi_ulong G_GNUC_UNUSED h2g_ulong_sat(u_long ul)
+static abi_ulong h2g_ulong_sat(u_long ul)
{
return MIN(ul, UINT32_MAX);
}
@@ -107,6 +107,129 @@ static abi_ulong G_GNUC_UNUSED h2g_ulong_sat(u_long ul)
*/
#define bsd_get_ncpu() 1
+/*
+ * This uses the undocumented oidfmt interface to find the kind of a requested
+ * sysctl, see /sys/kern/kern_sysctl.c:sysctl_sysctl_oidfmt() (compare to
+ * src/sbin/sysctl/sysctl.c)
+ */
+static int G_GNUC_UNUSED oidfmt(int *oid, int len, char *fmt, uint32_t *kind)
+{
+ int qoid[CTL_MAXNAME + 2];
+ uint8_t buf[BUFSIZ];
+ int i;
+ size_t j;
+
+ qoid[0] = CTL_SYSCTL;
+ qoid[1] = CTL_SYSCTL_OIDFMT;
+ memcpy(qoid + 2, oid, len * sizeof(int));
+
+ j = sizeof(buf);
+ i = sysctl(qoid, len + 2, buf, &j, 0, 0);
+ if (i) {
+ return i;
+ }
+
+ if (kind) {
+ *kind = *(uint32_t *)buf;
+ }
+
+ if (fmt) {
+ strcpy(fmt, (char *)(buf + sizeof(uint32_t)));
+ }
+ return 0;
+}
+
+/*
+ * Convert the old value from host to guest.
+ *
+ * For LONG and ULONG on ABI32, we need to 'down convert' the 8 byte quantities
+ * to 4 bytes. The caller setup a buffer in host memory to get this data from
+ * the kernel and pass it to us. We do the down conversion and adjust the
length
+ * so the caller knows what to write as the returned length into the target
when
+ * it copies the down converted values into the target.
+ *
+ * For normal integral types, we just need to byte swap. No size changes.
+ *
+ * For strings and node data, there's no conversion needed.
+ *
+ * For opaque data, per sysctl OID converts take care of it.
+ */
+static void G_GNUC_UNUSED h2g_old_sysctl(void *holdp, size_t *holdlen,
uint32_t kind)
+{
+ size_t len;
+ int hlen, glen;
+ uint8_t *hp, *gp;
+
+ /*
+ * Although rare, we can have arrays of sysctl. Both sysctl_old_ddb in
+ * kern_sysctl.c and show_var in sbin/sysctl/sysctl.c have code that loops
+ * this way. *holdlen has been set by the kernel to the host's length.
+ * Only LONG and ULONG on ABI32 have different sizes: see below.
+ */
+ gp = hp = (uint8_t *)holdp;
+ len = 0;
+ hlen = host_ctl_size[kind & CTLTYPE];
+ glen = guest_ctl_size[kind & CTLTYPE];
+
+ /*
+ * hlen == 0 for CTLTYPE_STRING and CTLTYPE_NODE, which need no conversion
+ * as well as CTLTYPE_OPAQUE, which needs special converters.
+ */
+ if (hlen == 0) {
+ return;
+ }
+
+ while (len < *holdlen) {
+ if (hlen == glen) {
+ switch (hlen) {
+ case 1:
+ /* Nothing needed: no byteswapping and assigning in place */
+ break;
+ case 2:
+ *(uint16_t *)gp = tswap16(*(uint16_t *)hp);
+ break;
+ case 4:
+ *(uint32_t *)gp = tswap32(*(uint32_t *)hp);
+ break;
+ case 8:
+ *(uint64_t *)gp = tswap64(*(uint64_t *)hp);
+ break;
+ default:
+ g_assert_not_reached();
+ }
+ } else {
+#ifdef TARGET_ABI32
+ /*
+ * Saturating assignment for the only two types that differ between
+ * 32-bit and 64-bit machines. All other integral types have the
+ * same, fixed size and will be converted w/o loss of precision
+ * in the above switch.
+ */
+ switch (kind & CTLTYPE) {
+ case CTLTYPE_LONG:
+ *(abi_long *)gp = tswap32(h2g_long_sat(*(long *)hp));
+ break;
+ case CTLTYPE_ULONG:
+ *(abi_ulong *)gp = tswap32(h2g_ulong_sat(*(u_long *)hp));
+ break;
+ default:
+ g_assert_not_reached();
+ }
+#else
+ g_assert_not_reached();
+#endif
+ }
+ gp += glen;
+ hp += hlen;
+ len += hlen;
+ }
+#ifdef TARGET_ABI32
+ if (hlen != glen) {
+ *holdlen = (*holdlen / hlen) * glen;
+ }
+#endif
+}
+
/* sysarch() is architecture dependent. */
abi_long do_freebsd_sysarch(void *cpu_env, abi_long arg1, abi_long arg2)
{
--
2.39.1
- [PULL 00/10] Bsd user 2023q1 patches, Warner Losh, 2023/03/01
- [PULL 01/10] bsd-user: Don't truncate the return value from freebsd_syscall, Warner Losh, 2023/03/01
- [PULL 02/10] build: Don't specify -no-pie for --static user-mode programs, Warner Losh, 2023/03/01
- [PULL 03/10] bsd-user: Add sysarch syscall, Warner Losh, 2023/03/01
- [PULL 04/10] bsd-user: various helper routines for sysctl, Warner Losh, 2023/03/01
- [PULL 05/10] bsd-user: Helper routines oidfmt,
Warner Losh <=
- [PULL 06/10] bsd-user: sysctl helper funtions: sysctl_name2oid and sysctl_oidfmt, Warner Losh, 2023/03/01
- [PULL 07/10] bsd-user: common routine do_freebsd_sysctl_oid for all sysctl variants, Warner Losh, 2023/03/01
- [PULL 08/10] bsd-user: Start translation of arch-specific sysctls, Warner Losh, 2023/03/01
- [PULL 09/10] bsd-user: do_freebsd_sysctl helper for sysctl(2), Warner Losh, 2023/03/01
- [PULL 10/10] bsd-user: implement sysctlbyname(2), Warner Losh, 2023/03/01
- Re: [PULL 00/10] Bsd user 2023q1 patches, Peter Maydell, 2023/03/02