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plugins: try and make plugin_insn_append more ergonomic

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Currently we make the assumption that the guest frontend loads all
op code bytes sequentially. This mostly holds up for regular fixed
encodings but some architectures like s390x like to re-read the
instruction which causes weirdness to occur. Rather than changing the
frontends make the plugin API a little more ergonomic and able to
handle the re-read case.

Stuff will still get strange if we read ahead of the opcode but so far
no front ends have done that and this patch asserts the case so we can
catch it early if they do.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Suggested-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20211026102234.3961636-21-alex.bennee@linaro.org>
This commit is contained in:
Alex Bennée 2021-10-26 11:22:26 +01:00
parent e83f79b3fa
commit 357af9be5c
4 changed files with 17 additions and 7 deletions
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3
accel/tcg/plugin-gen.c
View file

@ -876,9 +876,8 @@ void plugin_gen_insn_start(CPUState *cpu, const DisasContextBase *db)
struct qemu_plugin_tb *ptb = tcg_ctx->plugin_tb; struct qemu_plugin_tb *ptb = tcg_ctx->plugin_tb;
struct qemu_plugin_insn *pinsn; struct qemu_plugin_insn *pinsn;
pinsn = qemu_plugin_tb_insn_get(ptb); pinsn = qemu_plugin_tb_insn_get(ptb, db->pc_next);
tcg_ctx->plugin_insn = pinsn; tcg_ctx->plugin_insn = pinsn;
pinsn->vaddr = db->pc_next;
plugin_gen_empty_callback(PLUGIN_GEN_FROM_INSN); plugin_gen_empty_callback(PLUGIN_GEN_FROM_INSN);
/* /*

2
accel/tcg/translator.c
View file

@ -169,7 +169,7 @@ static inline void translator_maybe_page_protect(DisasContextBase *dcbase,
if (do_swap) { \ if (do_swap) { \
ret = swap_fn(ret); \ ret = swap_fn(ret); \
} \ } \
plugin_insn_append(&ret, sizeof(ret)); \ plugin_insn_append(pc, &ret, sizeof(ret)); \
return ret; \ return ret; \
} }

12
include/exec/plugin-gen.h
View file

@ -27,13 +27,21 @@ void plugin_gen_insn_end(void);
void plugin_gen_disable_mem_helpers(void); void plugin_gen_disable_mem_helpers(void);
void plugin_gen_empty_mem_callback(TCGv addr, uint32_t info); void plugin_gen_empty_mem_callback(TCGv addr, uint32_t info);
static inline void plugin_insn_append(const void *from, size_t size) static inline void plugin_insn_append(abi_ptr pc, const void *from, size_t size)
{ {
struct qemu_plugin_insn *insn = tcg_ctx->plugin_insn; struct qemu_plugin_insn *insn = tcg_ctx->plugin_insn;
abi_ptr off;
if (insn == NULL) { if (insn == NULL) {
return; return;
} }
off = pc - insn->vaddr;
if (off < insn->data->len) {
g_byte_array_set_size(insn->data, off);
} else if (off > insn->data->len) {
/* we have an unexpected gap */
g_assert_not_reached();
}
insn->data = g_byte_array_append(insn->data, from, size); insn->data = g_byte_array_append(insn->data, from, size);
} }
@ -62,7 +70,7 @@ static inline void plugin_gen_disable_mem_helpers(void)
static inline void plugin_gen_empty_mem_callback(TCGv addr, uint32_t info) static inline void plugin_gen_empty_mem_callback(TCGv addr, uint32_t info)
{ } { }
static inline void plugin_insn_append(const void *from, size_t size) static inline void plugin_insn_append(abi_ptr pc, const void *from, size_t size)
{ } { }
#endif /* CONFIG_PLUGIN */ #endif /* CONFIG_PLUGIN */

7
include/qemu/plugin.h
View file

@ -163,10 +163,12 @@ struct qemu_plugin_tb {
/** /**
* qemu_plugin_tb_insn_get(): get next plugin record for translation. * qemu_plugin_tb_insn_get(): get next plugin record for translation.
* * @tb: the internal tb context
* @pc: address of instruction
*/ */
static inline static inline
struct qemu_plugin_insn *qemu_plugin_tb_insn_get(struct qemu_plugin_tb *tb) struct qemu_plugin_insn *qemu_plugin_tb_insn_get(struct qemu_plugin_tb *tb,
uint64_t pc)
{ {
struct qemu_plugin_insn *insn; struct qemu_plugin_insn *insn;
int i, j; int i, j;
@ -179,6 +181,7 @@ struct qemu_plugin_insn *qemu_plugin_tb_insn_get(struct qemu_plugin_tb *tb)
g_byte_array_set_size(insn->data, 0); g_byte_array_set_size(insn->data, 0);
insn->calls_helpers = false; insn->calls_helpers = false;
insn->mem_helper = false; insn->mem_helper = false;
insn->vaddr = pc;
for (i = 0; i < PLUGIN_N_CB_TYPES; i++) { for (i = 0; i < PLUGIN_N_CB_TYPES; i++) {
for (j = 0; j < PLUGIN_N_CB_SUBTYPES; j++) { for (j = 0; j < PLUGIN_N_CB_SUBTYPES; j++) {