From 6ed6845532ef023ab9953e22f3aada6aa59657b9 Mon Sep 17 00:00:00 2001 From: Peter Maydell Date: Mon, 16 Sep 2019 15:15:34 +0100 Subject: [PATCH] target/arm/arm-semi: Restrict use of TaskState* The semihosting code needs accuss to the linux-user only TaskState pointer so it can set the semihosting errno per-thread for linux-user mode. At the moment we do this by having some ifdefs so that we define a 'ts' local in do_arm_semihosting() which is either a real TaskState * or just a CPUARMState *, depending on which mode we're compiling for. This is awkward if we want to refactor do_arm_semihosting() into other functions which might need to be passed the TaskState. Restrict usage of the TaskState local by: * making set_swi_errno() always take the CPUARMState pointer and (for the linux-user version) get TaskState from that * creating a new get_swi_errno() which reads the errno * having the two semihosting calls which need the TaskState for other purposes (SYS_GET_CMDLINE and SYS_HEAPINFO) define a variable with scope restricted to just that code Signed-off-by: Peter Maydell Reviewed-by: Richard Henderson Message-id: 20190916141544.17540-6-peter.maydell@linaro.org --- target/arm/arm-semi.c | 111 ++++++++++++++++++++++++------------------ 1 file changed, 63 insertions(+), 48 deletions(-) diff --git a/target/arm/arm-semi.c b/target/arm/arm-semi.c index a4741d7e11..2618588076 100644 --- a/target/arm/arm-semi.c +++ b/target/arm/arm-semi.c @@ -213,26 +213,45 @@ static GuestFD *get_guestfd(int guestfd) return gf; } -#ifdef CONFIG_USER_ONLY -static inline uint32_t set_swi_errno(TaskState *ts, uint32_t code) -{ - if (code == (uint32_t)-1) - ts->swi_errno = errno; - return code; -} -#else +/* + * The semihosting API has no concept of its errno being thread-safe, + * as the API design predates SMP CPUs and was intended as a simple + * real-hardware set of debug functionality. For QEMU, we make the + * errno be per-thread in linux-user mode; in softmmu it is a simple + * global, and we assume that the guest takes care of avoiding any races. + */ +#ifndef CONFIG_USER_ONLY static target_ulong syscall_err; +#include "exec/softmmu-semi.h" +#endif + static inline uint32_t set_swi_errno(CPUARMState *env, uint32_t code) { if (code == (uint32_t)-1) { +#ifdef CONFIG_USER_ONLY + CPUState *cs = env_cpu(env); + TaskState *ts = cs->opaque; + + ts->swi_errno = errno; +#else syscall_err = errno; +#endif } return code; } -#include "exec/softmmu-semi.h" +static inline uint32_t get_swi_errno(CPUARMState *env) +{ +#ifdef CONFIG_USER_ONLY + CPUState *cs = env_cpu(env); + TaskState *ts = cs->opaque; + + return ts->swi_errno; +#else + return syscall_err; #endif +} static target_ulong arm_semi_syscall_len; @@ -379,12 +398,12 @@ static target_ulong arm_gdb_syscall(ARMCPU *cpu, gdb_syscall_complete_cb cb, if (is_a64(env)) { \ if (get_user_u64(arg ## n, args + (n) * 8)) { \ errno = EFAULT; \ - return set_swi_errno(ts, -1); \ + return set_swi_errno(env, -1); \ } \ } else { \ if (get_user_u32(arg ## n, args + (n) * 4)) { \ errno = EFAULT; \ - return set_swi_errno(ts, -1); \ + return set_swi_errno(env, -1); \ } \ } \ } while (0) @@ -413,11 +432,6 @@ target_ulong do_arm_semihosting(CPUARMState *env) int nr; uint32_t ret; uint32_t len; -#ifdef CONFIG_USER_ONLY - TaskState *ts = cs->opaque; -#else - CPUARMState *ts = env; -#endif GuestFD *gf; if (is_a64(env)) { @@ -440,19 +454,19 @@ target_ulong do_arm_semihosting(CPUARMState *env) s = lock_user_string(arg0); if (!s) { errno = EFAULT; - return set_swi_errno(ts, -1); + return set_swi_errno(env, -1); } if (arg1 >= 12) { unlock_user(s, arg0, 0); errno = EINVAL; - return set_swi_errno(ts, -1); + return set_swi_errno(env, -1); } guestfd = alloc_guestfd(); if (guestfd < 0) { unlock_user(s, arg0, 0); errno = EMFILE; - return set_swi_errno(ts, -1); + return set_swi_errno(env, -1); } if (strcmp(s, ":tt") == 0) { @@ -466,7 +480,7 @@ target_ulong do_arm_semihosting(CPUARMState *env) ret = arm_gdb_syscall(cpu, arm_semi_open_cb, "open,%s,%x,1a4", arg0, (int)arg2+1, gdb_open_modeflags[arg1]); } else { - ret = set_swi_errno(ts, open(s, open_modeflags[arg1], 0644)); + ret = set_swi_errno(env, open(s, open_modeflags[arg1], 0644)); if (ret == (uint32_t)-1) { dealloc_guestfd(guestfd); } else { @@ -483,13 +497,13 @@ target_ulong do_arm_semihosting(CPUARMState *env) gf = get_guestfd(arg0); if (!gf) { errno = EBADF; - return set_swi_errno(ts, -1); + return set_swi_errno(env, -1); } if (use_gdb_syscalls()) { ret = arm_gdb_syscall(cpu, arm_semi_cb, "close,%x", gf->hostfd); } else { - ret = set_swi_errno(ts, close(gf->hostfd)); + ret = set_swi_errno(env, close(gf->hostfd)); } dealloc_guestfd(arg0); return ret; @@ -507,7 +521,7 @@ target_ulong do_arm_semihosting(CPUARMState *env) gf = get_guestfd(arg0); if (!gf) { errno = EBADF; - return set_swi_errno(ts, -1); + return set_swi_errno(env, -1); } if (use_gdb_syscalls()) { @@ -520,7 +534,7 @@ target_ulong do_arm_semihosting(CPUARMState *env) /* Return bytes not written on error */ return len; } - ret = set_swi_errno(ts, write(gf->hostfd, s, len)); + ret = set_swi_errno(env, write(gf->hostfd, s, len)); unlock_user(s, arg1, 0); if (ret == (uint32_t)-1) { ret = 0; @@ -537,7 +551,7 @@ target_ulong do_arm_semihosting(CPUARMState *env) gf = get_guestfd(arg0); if (!gf) { errno = EBADF; - return set_swi_errno(ts, -1); + return set_swi_errno(env, -1); } if (use_gdb_syscalls()) { @@ -551,7 +565,7 @@ target_ulong do_arm_semihosting(CPUARMState *env) return len; } do { - ret = set_swi_errno(ts, read(gf->hostfd, s, len)); + ret = set_swi_errno(env, read(gf->hostfd, s, len)); } while (ret == -1 && errno == EINTR); unlock_user(s, arg1, len); if (ret == (uint32_t)-1) { @@ -569,7 +583,7 @@ target_ulong do_arm_semihosting(CPUARMState *env) gf = get_guestfd(arg0); if (!gf) { errno = EBADF; - return set_swi_errno(ts, -1); + return set_swi_errno(env, -1); } if (use_gdb_syscalls()) { @@ -584,14 +598,14 @@ target_ulong do_arm_semihosting(CPUARMState *env) gf = get_guestfd(arg0); if (!gf) { errno = EBADF; - return set_swi_errno(ts, -1); + return set_swi_errno(env, -1); } if (use_gdb_syscalls()) { return arm_gdb_syscall(cpu, arm_semi_cb, "lseek,%x,%x,0", gf->hostfd, arg1); } else { - ret = set_swi_errno(ts, lseek(gf->hostfd, arg1, SEEK_SET)); + ret = set_swi_errno(env, lseek(gf->hostfd, arg1, SEEK_SET)); if (ret == (uint32_t)-1) return -1; return 0; @@ -602,7 +616,7 @@ target_ulong do_arm_semihosting(CPUARMState *env) gf = get_guestfd(arg0); if (!gf) { errno = EBADF; - return set_swi_errno(ts, -1); + return set_swi_errno(env, -1); } if (use_gdb_syscalls()) { @@ -610,7 +624,7 @@ target_ulong do_arm_semihosting(CPUARMState *env) gf->hostfd, arm_flen_buf(cpu)); } else { struct stat buf; - ret = set_swi_errno(ts, fstat(gf->hostfd, &buf)); + ret = set_swi_errno(env, fstat(gf->hostfd, &buf)); if (ret == (uint32_t)-1) return -1; return buf.st_size; @@ -628,9 +642,9 @@ target_ulong do_arm_semihosting(CPUARMState *env) s = lock_user_string(arg0); if (!s) { errno = EFAULT; - return set_swi_errno(ts, -1); + return set_swi_errno(env, -1); } - ret = set_swi_errno(ts, remove(s)); + ret = set_swi_errno(env, remove(s)); unlock_user(s, arg0, 0); } return ret; @@ -648,9 +662,9 @@ target_ulong do_arm_semihosting(CPUARMState *env) s2 = lock_user_string(arg2); if (!s || !s2) { errno = EFAULT; - ret = set_swi_errno(ts, -1); + ret = set_swi_errno(env, -1); } else { - ret = set_swi_errno(ts, rename(s, s2)); + ret = set_swi_errno(env, rename(s, s2)); } if (s2) unlock_user(s2, arg2, 0); @@ -661,7 +675,7 @@ target_ulong do_arm_semihosting(CPUARMState *env) case TARGET_SYS_CLOCK: return clock() / (CLOCKS_PER_SEC / 100); case TARGET_SYS_TIME: - return set_swi_errno(ts, time(NULL)); + return set_swi_errno(env, time(NULL)); case TARGET_SYS_SYSTEM: GET_ARG(0); GET_ARG(1); @@ -672,18 +686,14 @@ target_ulong do_arm_semihosting(CPUARMState *env) s = lock_user_string(arg0); if (!s) { errno = EFAULT; - return set_swi_errno(ts, -1); + return set_swi_errno(env, -1); } - ret = set_swi_errno(ts, system(s)); + ret = set_swi_errno(env, system(s)); unlock_user(s, arg0, 0); return ret; } case TARGET_SYS_ERRNO: -#ifdef CONFIG_USER_ONLY - return ts->swi_errno; -#else - return syscall_err; -#endif + return get_swi_errno(env); case TARGET_SYS_GET_CMDLINE: { /* Build a command-line from the original argv. @@ -706,6 +716,8 @@ target_ulong do_arm_semihosting(CPUARMState *env) int status = 0; #if !defined(CONFIG_USER_ONLY) const char *cmdline; +#else + TaskState *ts = cs->opaque; #endif GET_ARG(0); GET_ARG(1); @@ -733,21 +745,21 @@ target_ulong do_arm_semihosting(CPUARMState *env) if (output_size > input_size) { /* Not enough space to store command-line arguments. */ errno = E2BIG; - return set_swi_errno(ts, -1); + return set_swi_errno(env, -1); } /* Adjust the command-line length. */ if (SET_ARG(1, output_size - 1)) { /* Couldn't write back to argument block */ errno = EFAULT; - return set_swi_errno(ts, -1); + return set_swi_errno(env, -1); } /* Lock the buffer on the ARM side. */ output_buffer = lock_user(VERIFY_WRITE, arg0, output_size, 0); if (!output_buffer) { errno = EFAULT; - return set_swi_errno(ts, -1); + return set_swi_errno(env, -1); } /* Copy the command-line arguments. */ @@ -763,7 +775,7 @@ target_ulong do_arm_semihosting(CPUARMState *env) if (copy_from_user(output_buffer, ts->info->arg_start, output_size)) { errno = EFAULT; - status = set_swi_errno(ts, -1); + status = set_swi_errno(env, -1); goto out; } @@ -785,6 +797,9 @@ target_ulong do_arm_semihosting(CPUARMState *env) target_ulong retvals[4]; target_ulong limit; int i; +#ifdef CONFIG_USER_ONLY + TaskState *ts = cs->opaque; +#endif GET_ARG(0); @@ -834,7 +849,7 @@ target_ulong do_arm_semihosting(CPUARMState *env) if (fail) { /* Couldn't write back to argument block */ errno = EFAULT; - return set_swi_errno(ts, -1); + return set_swi_errno(env, -1); } } return 0;