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-...@nongnu.org
Signed-off-by: Richard Henderson <richard.hender...@linaro.org>
---
linux-user/arm/target_signal.h | 2 +
linux-user/arm/signal.c | 170 +++++++++++++++++++--------------
2 files changed, 100 insertions(+), 72 deletions(-)
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);
+}
--
2.25.1
