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));
+ 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
--
Alex Bennée
Virtualisation Tech Lead @ Linaro
