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semihosting: Add target_strlen for softmmu-uaccess.h

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Mirror the interface of the user-only function of the same name.
Use probe_access_flags for the common case of ram, and
cpu_memory_rw_debug for the uncommon case of mmio.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
v3: Use probe_access_flags (pmm)
This commit is contained in:
Richard Henderson 2022-04-27 21:03:12 -07:00
parent b89350e830
commit 5f9ca6f3c5
2 changed files with 52 additions and 0 deletions
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3
include/semihosting/softmmu-uaccess.h
View file

@ -53,4 +53,7 @@ void softmmu_unlock_user(CPUArchState *env, void *p,
target_ulong addr, target_ulong len);
#define unlock_user(s, args, len) softmmu_unlock_user(env, s, args, len)
ssize_t softmmu_strlen_user(CPUArchState *env, target_ulong addr);
#define target_strlen(p) softmmu_strlen_user(env, p)
#endif /* SEMIHOSTING_SOFTMMU_UACCESS_H */

49
semihosting/uaccess.c
View file

@ -8,6 +8,7 @@
*/
#include "qemu/osdep.h"
#include "exec/exec-all.h"
#include "semihosting/softmmu-uaccess.h"
void *softmmu_lock_user(CPUArchState *env, target_ulong addr,
@ -23,6 +24,54 @@ void *softmmu_lock_user(CPUArchState *env, target_ulong addr,
return p;
}
ssize_t softmmu_strlen_user(CPUArchState *env, target_ulong addr)
{
int mmu_idx = cpu_mmu_index(env, false);
size_t len = 0;
while (1) {
size_t left_in_page;
int flags;
void *h;
/* Find the number of bytes remaining in the page. */
left_in_page = TARGET_PAGE_SIZE - (addr & ~TARGET_PAGE_MASK);
flags = probe_access_flags(env, addr, MMU_DATA_LOAD,
mmu_idx, true, &h, 0);
if (flags & TLB_INVALID_MASK) {
return -1;
}
if (flags & TLB_MMIO) {
do {
uint8_t c;
if (cpu_memory_rw_debug(env_cpu(env), addr, &c, 1, 0)) {
return -1;
}
if (c == 0) {
return len;
}
addr++;
len++;
if (len > INT32_MAX) {
return -1;
}
} while (--left_in_page != 0);
} else {
char *p = memchr(h, 0, left_in_page);
if (p) {
len += p - (char *)h;
return len <= INT32_MAX ? (ssize_t)len : -1;
}
addr += left_in_page;
len += left_in_page;
if (len > INT32_MAX) {
return -1;
}
}
}
}
char *softmmu_lock_user_string(CPUArchState *env, target_ulong addr)
{
/* TODO: Make this something that isn't fixed size. */