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[174.21.70.228]) by smtp.gmail.com with ESMTPSA id y18sm305297pgk.53.2021.06.15.18.12.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 15 Jun 2021 18:12:12 -0700 (PDT) From: Richard Henderson To: qemu-devel@nongnu.org Subject: [PATCH 04/21] linux-user/arm: Implement setup_sigtramp Date: Tue, 15 Jun 2021 18:11:52 -0700 Message-Id: <20210616011209.1446045-5-richard.henderson@linaro.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210616011209.1446045-1-richard.henderson@linaro.org> References: <20210616011209.1446045-1-richard.henderson@linaro.org> MIME-Version: 1.0 Received-SPF: pass client-ip=2607:f8b0:4864:20::102e; envelope-from=richard.henderson@linaro.org; helo=mail-pj1-x102e.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: qemu-arm@nongnu.org, alex.bennee@linaro.org, laurent@vivier.eu Errors-To: qemu-devel-bounces+patch=linaro.org@nongnu.org Sender: "Qemu-devel" ARM is more complicated than the others, in that we also have trampolines for using SA_RESTORER with FDPIC, and we need to create trampolines for both ARM and Thumb modes. Cc: qemu-arm@nongnu.org Signed-off-by: Richard Henderson --- linux-user/arm/target_signal.h | 2 + linux-user/arm/signal.c | 170 +++++++++++++++++++-------------- 2 files changed, 100 insertions(+), 72 deletions(-) -- 2.25.1 diff --git a/linux-user/arm/target_signal.h b/linux-user/arm/target_signal.h index 0998dd6dfa..1e7fb0cecb 100644 --- a/linux-user/arm/target_signal.h +++ b/linux-user/arm/target_signal.h @@ -22,4 +22,6 @@ typedef struct target_sigaltstack { #include "../generic/signal.h" #define TARGET_ARCH_HAS_SETUP_FRAME +#define TARGET_ARCH_HAS_SIGTRAMP_PAGE 1 + #endif /* ARM_TARGET_SIGNAL_H */ diff --git a/linux-user/arm/signal.c b/linux-user/arm/signal.c index 2d30345fc2..b7c3c80c75 100644 --- a/linux-user/arm/signal.c +++ b/linux-user/arm/signal.c @@ -101,13 +101,12 @@ struct sigframe_v1 { struct target_sigcontext sc; abi_ulong extramask[TARGET_NSIG_WORDS-1]; - abi_ulong retcode[4]; }; struct sigframe_v2 { struct target_ucontext_v2 uc; - abi_ulong retcode[4]; + abi_ulong fdpic_ret; }; struct rt_sigframe_v1 @@ -116,49 +115,20 @@ struct rt_sigframe_v1 abi_ulong puc; struct target_siginfo info; struct target_ucontext_v1 uc; - abi_ulong retcode[4]; }; struct rt_sigframe_v2 { struct target_siginfo info; struct target_ucontext_v2 uc; - abi_ulong retcode[4]; + abi_ulong fdpic_ret; }; /* - * For ARM syscalls, we encode the syscall number into the instruction. + * Stubs needed to make sure the FD register (r9) contains the right value. + * There are 4 of them, each consuming 8 bytes. */ -#define SWI_SYS_SIGRETURN (0xef000000|(TARGET_NR_sigreturn + ARM_SYSCALL_BASE)) -#define SWI_SYS_RT_SIGRETURN (0xef000000|(TARGET_NR_rt_sigreturn + ARM_SYSCALL_BASE)) - -/* - * For Thumb syscalls, we pass the syscall number via r7. We therefore - * need two 16-bit instructions. - */ -#define SWI_THUMB_SIGRETURN (0xdf00 << 16 | 0x2700 | (TARGET_NR_sigreturn)) -#define SWI_THUMB_RT_SIGRETURN (0xdf00 << 16 | 0x2700 | (TARGET_NR_rt_sigreturn)) - -static const abi_ulong retcodes[4] = { - SWI_SYS_SIGRETURN, SWI_THUMB_SIGRETURN, - SWI_SYS_RT_SIGRETURN, SWI_THUMB_RT_SIGRETURN -}; - -/* - * Stub needed to make sure the FD register (r9) contains the right - * value. - */ -static const unsigned long sigreturn_fdpic_codes[3] = { - 0xe59fc004, /* ldr r12, [pc, #4] to read function descriptor */ - 0xe59c9004, /* ldr r9, [r12, #4] to setup GOT */ - 0xe59cf000 /* ldr pc, [r12] to jump into restorer */ -}; - -static const unsigned long sigreturn_fdpic_thumb_codes[3] = { - 0xc008f8df, /* ldr r12, [pc, #8] to read function descriptor */ - 0x9004f8dc, /* ldr r9, [r12, #4] to setup GOT */ - 0xf000f8dc /* ldr pc, [r12] to jump into restorer */ -}; +static abi_ulong sigreturn_fdpic_tramp; static inline int valid_user_regs(CPUARMState *regs) { @@ -219,13 +189,12 @@ get_sigframe(struct target_sigaction *ka, CPUARMState *regs, int framesize) static int setup_return(CPUARMState *env, struct target_sigaction *ka, - abi_ulong *rc, abi_ulong frame_addr, int usig, abi_ulong rc_addr) + abi_ulong frame_addr, int usig) { abi_ulong handler = 0; abi_ulong handler_fdpic_GOT = 0; abi_ulong retcode; - - int thumb; + int thumb, retcode_idx; int is_fdpic = info_is_fdpic(((TaskState *)thread_cpu->opaque)->info); if (is_fdpic) { @@ -243,6 +212,7 @@ setup_return(CPUARMState *env, struct target_sigaction *ka, } thumb = handler & 1; + retcode_idx = thumb + (ka->sa_flags & TARGET_SA_SIGINFO ? 2 : 0); uint32_t cpsr = cpsr_read(env); @@ -260,37 +230,24 @@ setup_return(CPUARMState *env, struct target_sigaction *ka, if (ka->sa_flags & TARGET_SA_RESTORER) { if (is_fdpic) { - /* For FDPIC we ensure that the restorer is called with a - * correct r9 value. For that we need to write code on - * the stack that sets r9 and jumps back to restorer - * value. + /* + * For FDPIC we ensure that the restorer is called with a + * correct r9 value. For that we use a special trampoline + * that reads the function descriptor from the frame, + * sets r9 and jumps back to restorer value. */ - if (thumb) { - __put_user(sigreturn_fdpic_thumb_codes[0], rc); - __put_user(sigreturn_fdpic_thumb_codes[1], rc + 1); - __put_user(sigreturn_fdpic_thumb_codes[2], rc + 2); - __put_user((abi_ulong)ka->sa_restorer, rc + 3); - } else { - __put_user(sigreturn_fdpic_codes[0], rc); - __put_user(sigreturn_fdpic_codes[1], rc + 1); - __put_user(sigreturn_fdpic_codes[2], rc + 2); - __put_user((abi_ulong)ka->sa_restorer, rc + 3); - } - - retcode = rc_addr + thumb; + abi_ulong fd_ofs = (retcode_idx & 2 + ? offsetof(struct rt_sigframe_v2, fdpic_ret) + : offsetof(struct sigframe_v2, fdpic_ret)); + put_user_ual(ka->sa_restorer, frame_addr + fd_ofs); + /* Each trampoline variant consumes 8-byte slot. */ + retcode = sigreturn_fdpic_tramp + retcode_idx * 8 + thumb; } else { retcode = ka->sa_restorer; } } else { - unsigned int idx = thumb; - - if (ka->sa_flags & TARGET_SA_SIGINFO) { - idx += 2; - } - - __put_user(retcodes[idx], rc); - - retcode = rc_addr + thumb; + /* Each trampoline variant consumes one 4-byte slot. */ + retcode = default_sigreturn + retcode_idx * 4 + thumb; } env->regs[0] = usig; @@ -394,8 +351,7 @@ static void setup_frame_v1(int usig, struct target_sigaction *ka, __put_user(set->sig[i], &frame->extramask[i - 1]); } - if (setup_return(regs, ka, frame->retcode, frame_addr, usig, - frame_addr + offsetof(struct sigframe_v1, retcode))) { + if (setup_return(regs, ka, frame_addr, usig)) { goto sigsegv; } @@ -419,8 +375,7 @@ static void setup_frame_v2(int usig, struct target_sigaction *ka, setup_sigframe_v2(&frame->uc, set, regs); - if (setup_return(regs, ka, frame->retcode, frame_addr, usig, - frame_addr + offsetof(struct sigframe_v2, retcode))) { + if (setup_return(regs, ka, frame_addr, usig)) { goto sigsegv; } @@ -475,8 +430,7 @@ static void setup_rt_frame_v1(int usig, struct target_sigaction *ka, __put_user(set->sig[i], &frame->uc.tuc_sigmask.sig[i]); } - if (setup_return(env, ka, frame->retcode, frame_addr, usig, - frame_addr + offsetof(struct rt_sigframe_v1, retcode))) { + if (setup_return(env, ka, frame_addr, usig)) { goto sigsegv; } @@ -509,8 +463,7 @@ static void setup_rt_frame_v2(int usig, struct target_sigaction *ka, setup_sigframe_v2(&frame->uc, set, env); - if (setup_return(env, ka, frame->retcode, frame_addr, usig, - frame_addr + offsetof(struct rt_sigframe_v2, retcode))) { + if (setup_return(env, ka, frame_addr, usig)) { goto sigsegv; } @@ -841,3 +794,76 @@ long do_rt_sigreturn(CPUARMState *env) return do_rt_sigreturn_v1(env); } } + +void setup_sigtramp(abi_ulong sigtramp_page) +{ + enum { + /* For ARM, we encode the syscall number into the instruction. */ + SWI_SYS_SIGRETURN = + 0xef000000 | (TARGET_NR_sigreturn + ARM_SYSCALL_BASE), + SWI_SYS_RT_SIGRETURN = + 0xef000000 | (TARGET_NR_rt_sigreturn + ARM_SYSCALL_BASE), + + /* + * For Thumb , we pass the syscall number via r7. + * We therefore need two 16-bit instructions. + */ + SWI_THUMB_SIGRETURN = + 0xdf00 << 16 | 0x2700 | TARGET_NR_sigreturn, + SWI_THUMB_RT_SIGRETURN = + 0xdf00 << 16 | 0x2700 | TARGET_NR_rt_sigreturn, + + SIGFRAME_FDPIC_OFS = offsetof(struct sigframe_v2, fdpic_ret), + RT_SIGFRAME_FDPIC_OFS = offsetof(struct rt_sigframe_v2, fdpic_ret), + }; + + uint32_t total_size = 4 * 4 + 2 * 8; + uint32_t *tramp = lock_user(VERIFY_WRITE, sigtramp_page, total_size, 0); + uint32_t i = 0; + + assert(tramp != NULL); + + default_sigreturn = sigtramp_page; + __put_user(SWI_SYS_SIGRETURN, &tramp[i++]); + __put_user(SWI_THUMB_SIGRETURN, &tramp[i++]); + __put_user(SWI_SYS_RT_SIGRETURN, &tramp[i++]); + __put_user(SWI_THUMB_RT_SIGRETURN, &tramp[i++]); + + /* + * FDPIC require trampolines to call sa_restorer. + * + * ARM versions use: + * ldr r9, [sp, #ofs] + * ldmia r9, {r9, pc} + * + * Thumb versions use: + * ldrd r9, r10, [sp, #ofs] + * bx r10 + * nop + */ + sigreturn_fdpic_tramp = sigtramp_page + i * 4; + + /* ARM sigframe */ + _Static_assert(SIGFRAME_FDPIC_OFS <= 0xfff); + __put_user(0xe59d9000 | SIGFRAME_FDPIC_OFS, &tramp[i++]); + __put_user(0xe8998200, &tramp[i++]); + + /* Thumb sigframe */ + _Static_assert(SIGFRAME_FDPIC_OFS <= 0xff << 2); + _Static_assert((SIGFRAME_FDPIC_OFS & 3) == 0); + __put_user(0x9a00e9dd | (SIGFRAME_FDPIC_OFS << 14), &tramp[i++]); + __put_user(0x46c04750, &tramp[i++]); + + /* ARM rt_sigframe */ + _Static_assert(RT_SIGFRAME_FDPIC_OFS <= 0xfff); + __put_user(0xe59d9000 | RT_SIGFRAME_FDPIC_OFS, &tramp[i++]); + __put_user(0xe8998200, &tramp[i++]); + + /* Thumb rt_sigframe */ + _Static_assert(RT_SIGFRAME_FDPIC_OFS <= 0xff << 2); + _Static_assert((RT_SIGFRAME_FDPIC_OFS & 3) == 0); + __put_user(0x9a00e9dd | (RT_SIGFRAME_FDPIC_OFS << 14), &tramp[i++]); + __put_user(0x46c04750, &tramp[i++]); + + unlock_user(tramp, sigtramp_page, total_size); +}