Pierrick Bouvier <pierrick.bouv...@linaro.org> writes: > On 6/27/25 2:17 AM, Alex Bennée wrote: >> Pierrick Bouvier <pierrick.bouv...@linaro.org> writes: >> >>> On 6/26/25 9:37 AM, Alex Bennée wrote: >>>> Alex Bennée <alex.ben...@linaro.org> writes: >>>> >>>>> Rowan Hart <rowanbh...@gmail.com> writes: >>>>> >>>>>> This patch series adds several new API functions focused on enabling use >>>>>> cases around reading and writing guest memory from QEMU plugins. To >>>>>> support >>>>>> these new APIs, some utility functionality around retrieving information >>>>>> about >>>>>> address spaces is added as well. >>>>> >>>>> Queued to plugins/next, thanks. >>>> So this fails a number of the CI tests, mostly due to 32 bit issues: >>>> https://gitlab.com/stsquad/qemu/-/pipelines/1890883927/failures >>>> The tci failure is easy enough: >>>> --8<---------------cut here---------------start------------->8--- >>>> modified tests/tcg/x86_64/Makefile.softmmu-target >>>> @@ -34,9 +34,11 @@ memory: CFLAGS+=-DCHECK_UNALIGNED=1 >>>> # Running >>>> QEMU_OPTS+=-device isa-debugcon,chardev=output -device >>>> isa-debug-exit,iobase=0xf4,iosize=0x4 -kernel >>>> +ifeq ($(CONFIG_PLUGIN),y) >>>> run-plugin-patch-target-with-libpatch.so: \ >>>> >>>> PLUGIN_ARGS=$(COMMA)target=ffc0$(COMMA)patch=9090$(COMMA)use_hwaddr=true >>>> run-plugin-patch-target-with-libpatch.so: \ >>>> CHECK_PLUGIN_OUTPUT_COMMAND=$(X64_SYSTEM_SRC)/validate-patch.py >>>> $@.out >>>> run-plugin-patch-target-with-libpatch.so: patch-target libpatch.so >>>> EXTRA_RUNS+=run-plugin-patch-target-with-libpatch.so >>>> +endif >>>> --8<---------------cut here---------------end--------------->8--- >>>> The other problem is trying to stuff a uint64_t into a void * on 32 >>>> bit. >>>> We did disable plugins for 32 bit but then reverted because we were able >>>> to fixup the cases: >>>> cf2a78cbbb (deprecation: don't enable TCG plugins by default on 32 >>>> bit hosts) >>>> db7a06ade1 (configure: reenable plugins by default for 32-bit hosts) >>>> So I don't what is easier: >>>> - re-deprecate for 32 bit systems >>>> - only build libpatch on 64 bit systems >>>> - fix libpatch to handle being built on 32 bit systems >>>> >>> >>> More context: >>> ../tests/tcg/plugins/patch.c: In function ‘patch_hwaddr’: >>> ../tests/tcg/plugins/patch.c:50:21: error: cast from pointer to >>> integer of different size [-Werror=pointer-to-int-cast] >>> 50 | uint64_t addr = (uint64_t)userdata; >>> | ^ >>> ../tests/tcg/plugins/patch.c: In function ‘patch_vaddr’: >>> ../tests/tcg/plugins/patch.c:93:21: error: cast from pointer to >>> integer of different size [-Werror=pointer-to-int-cast] >>> 93 | uint64_t addr = (uint64_t)userdata; >>> | ^ >>> ../tests/tcg/plugins/patch.c: In function ‘vcpu_tb_trans_cb’: >>> ../tests/tcg/plugins/patch.c:159:54: error: cast to pointer from >>> integer of different size [-Werror=int-to-pointer-cast] >>> 159 | (void *)addr); >>> | ^ >>> ../tests/tcg/plugins/patch.c:163:54: error: cast to pointer from >>> integer of different size [-Werror=int-to-pointer-cast] >>> 163 | (void *)addr); >>> | >>> >>> Since we disabled 64 bit targets on 32 bit hosts, and that data passed >>> by pointers concern addresses, it should be safe to cast values to >>> (uintptr_t) instead of (uint64_t). >> Something like this? >> --8<---------------cut here---------------start------------->8--- >> modified tests/tcg/plugins/patch.c >> @@ -47,10 +47,10 @@ static GByteArray *str_to_bytes(const char *str) >> static void patch_hwaddr(unsigned int vcpu_index, void >> *userdata) >> { >> - uint64_t addr = (uint64_t)userdata; >> + uintptr_t addr = (uintptr_t) userdata; >> g_autoptr(GString) str = g_string_new(NULL); >> g_string_printf(str, "patching: @0x%" >> - PRIx64 "\n", >> + PRIxPTR "\n", >> addr); >> qemu_plugin_outs(str->str); >> @@ -90,7 +90,7 @@ static void patch_hwaddr(unsigned int >> vcpu_index, void *userdata) >> static void patch_vaddr(unsigned int vcpu_index, void *userdata) >> { >> - uint64_t addr = (uint64_t)userdata; >> + uintptr_t addr = (uintptr_t) userdata; >> uint64_t hwaddr = 0; >> if (!qemu_plugin_translate_vaddr(addr, &hwaddr)) { >> qemu_plugin_outs("Failed to translate vaddr\n"); >> @@ -98,7 +98,7 @@ static void patch_vaddr(unsigned int vcpu_index, void >> *userdata) >> } >> g_autoptr(GString) str = g_string_new(NULL); >> g_string_printf(str, "patching: @0x%" >> - PRIx64 " hw: @0x%" PRIx64 "\n", >> + PRIxPTR " hw: @0x%" PRIx64 "\n", >> addr, hwaddr); >> qemu_plugin_outs(str->str); >> @@ -132,19 +132,29 @@ static void patch_vaddr(unsigned int >> vcpu_index, void *userdata) >> */ >> static void vcpu_tb_trans_cb(qemu_plugin_id_t id, struct qemu_plugin_tb >> *tb) >> { >> - uint64_t addr = 0; >> g_autoptr(GByteArray) insn_data = g_byte_array_new(); >> + uintptr_t addr = 0; >> + >> for (size_t i = 0; i < qemu_plugin_tb_n_insns(tb); i++) { >> struct qemu_plugin_insn *insn = qemu_plugin_tb_get_insn(tb, i); >> + uint64_t vaddr = qemu_plugin_insn_vaddr(insn); >> if (use_hwaddr) { >> - uint64_t vaddr = qemu_plugin_insn_vaddr(insn); >> - if (!qemu_plugin_translate_vaddr(vaddr, &addr)) { >> + uint64_t hwaddr = 0; >> + if (!qemu_plugin_translate_vaddr(vaddr, &hwaddr)) { >> qemu_plugin_outs("Failed to translate vaddr\n"); >> continue; >> } >> + /* >> + * As we cannot emulate 64 bit systems on 32 bit hosts we >> + * should never see the top bits set, hence we can safely >> + * cast to uintptr_t. >> + */ >> + g_assert(!(hwaddr & ~UINTPTR_MAX)); > > We would have so many other problems before plugins if this hypothesis > was not true (all the usage of vaddr type in the codebase would be > broken). So the assert will not detect anything we are not aware about > already. > > If we want to mention this assumption for plugins users, the plugins > documentation is probably a better place than one random plugin.
Well we could change the API function signature to return uintptr_t? > >> + addr = (uintptr_t) hwaddr; >> } else { >> - addr = qemu_plugin_insn_vaddr(insn); >> + g_assert(!(vaddr & ~UINTPTR_MAX)); >> + addr = (uintptr_t) vaddr; >> } >> g_byte_array_set_size(insn_data, >> qemu_plugin_insn_size(insn)); >> @@ -156,11 +166,11 @@ static void vcpu_tb_trans_cb(qemu_plugin_id_t id, >> struct qemu_plugin_tb *tb) >> if (use_hwaddr) { >> qemu_plugin_register_vcpu_tb_exec_cb(tb, patch_hwaddr, >> >> QEMU_PLUGIN_CB_NO_REGS, >> - (void *)addr); >> + (void *) addr); >> } else { >> qemu_plugin_register_vcpu_tb_exec_cb(tb, patch_vaddr, >> >> QEMU_PLUGIN_CB_NO_REGS, >> - (void *)addr); >> + (void *) addr); >> } >> } >> } >> --8<---------------cut here---------------end--------------->8--- >> >>> >>> Pierrick >> > > For the rest, it looks good to me. > > Thanks, > Pierrick -- Alex Bennée Virtualisation Tech Lead @ Linaro