On Tue, Feb 14, 2023 at 2:16 PM Richard Henderson < richard.hender...@linaro.org> wrote:
> On 2/13/23 14:27, Warner Losh wrote: > > +/* > > + * Convert the old value from host to target. > > host vs guest is clearer language; "target" gets overloaded, even though > still present in > the code base. > OK. Will do. We have that all over the place upstream... I'll start there too... > > > + * > > + * 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 h2t_old_sysctl(void *holdp, size_t *holdlen, > uint32_t kind) > > h2g. > OK. > > + /* > > + * 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 == tlen) { > > + switch (hlen) { > > + case 1: > > + /* Nothing needed: no byteswapping and assigning in > place */ > > + break; > > + case 2: > > + *(uint16_t *)tp = tswap16(*(uint16_t *)hp); > > + break; > > + case 4: > > + *(uint32_t *)tp = tswap32(*(uint32_t *)hp); > > + break; > > + case 8: > > + *(uint64_t *)tp = tswap64(*(uint64_t *)hp); > > + break; > > + } > > default: g_assert_not_reached(). > Ah! I need that in several places... Thanks. > > + } > > +#ifdef TARGET_ABI32 > > + else { > > + /* > > + * 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 *)tp = tswap32(h2t_long_sat(*(long *)hp)); > > + break; > > + case CTLTYPE_ULONG: > > + *(abi_ulong *)tp = tswap32(h2t_ulong_sat(*(u_long > *)hp)); > > + break; > > + } > > default: g_assert_not_reached(). > > > + } > > +#endif > > #else > g_assert_not_reached(); > Gotcha... Thanks! Warner > > r~ >