diff mbox series

[PULL,20/26] linux-user/riscv: Implement setup_sigtramp

Message ID 20211004074421.3141222-21-laurent@vivier.eu
State Accepted
Commit 3c62b5d2015b8292d4453f8174abf5fadbc6cc0f
Headers show
Series [PULL,01/26] linux-user: Add infrastructure for a signal trampoline page | expand

Commit Message

Laurent Vivier Oct. 4, 2021, 7:44 a.m. UTC 
From: Richard Henderson <richard.henderson@linaro.org>


Create and record the rt signal trampoline.

This fixes a bug wrt libgcc fallback unwinding.  It expects
the stack pointer to point to the siginfo_t, whereas we had
inexplicably placed our private signal trampoline at the start
of the signal frame instead of the end.  Now moot because we
have removed it from the stack frame entirely.

Reviewed-by: Alistair Francis <alistair.francis@wdc.com>

Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

Message-Id: <20210929130553.121567-21-richard.henderson@linaro.org>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>

---
 linux-user/riscv/signal.c        | 22 +++++++++++++---------
 linux-user/riscv/target_signal.h |  2 ++
 2 files changed, 15 insertions(+), 9 deletions(-)

-- 
2.31.1
diff mbox series

Patch

diff --git a/linux-user/riscv/signal.c b/linux-user/riscv/signal.c
index f7f33bc90aed..a0f9542ce39a 100644
--- a/linux-user/riscv/signal.c
+++ b/linux-user/riscv/signal.c
@@ -47,7 +47,6 @@  struct target_ucontext {
 };
 
 struct target_rt_sigframe {
-    uint32_t tramp[2]; /* not in kernel, which uses VDSO instead */
     struct target_siginfo info;
     struct target_ucontext uc;
 };
@@ -105,12 +104,6 @@  static void setup_ucontext(struct target_ucontext *uc,
     setup_sigcontext(&uc->uc_mcontext, env);
 }
 
-static inline void install_sigtramp(uint32_t *tramp)
-{
-    __put_user(0x08b00893, tramp + 0);  /* li a7, 139 = __NR_rt_sigreturn */
-    __put_user(0x00000073, tramp + 1);  /* ecall */
-}
-
 void setup_rt_frame(int sig, struct target_sigaction *ka,
                     target_siginfo_t *info,
                     target_sigset_t *set, CPURISCVState *env)
@@ -127,14 +120,13 @@  void setup_rt_frame(int sig, struct target_sigaction *ka,
 
     setup_ucontext(&frame->uc, env, set);
     tswap_siginfo(&frame->info, info);
-    install_sigtramp(frame->tramp);
 
     env->pc = ka->_sa_handler;
     env->gpr[xSP] = frame_addr;
     env->gpr[xA0] = sig;
     env->gpr[xA1] = frame_addr + offsetof(struct target_rt_sigframe, info);
     env->gpr[xA2] = frame_addr + offsetof(struct target_rt_sigframe, uc);
-    env->gpr[xRA] = frame_addr + offsetof(struct target_rt_sigframe, tramp);
+    env->gpr[xRA] = default_rt_sigreturn;
 
     return;
 
@@ -203,3 +195,15 @@  badframe:
     force_sig(TARGET_SIGSEGV);
     return 0;
 }
+
+void setup_sigtramp(abi_ulong sigtramp_page)
+{
+    uint32_t *tramp = lock_user(VERIFY_WRITE, sigtramp_page, 8, 0);
+    assert(tramp != NULL);
+
+    __put_user(0x08b00893, tramp + 0);  /* li a7, 139 = __NR_rt_sigreturn */
+    __put_user(0x00000073, tramp + 1);  /* ecall */
+
+    default_rt_sigreturn = sigtramp_page;
+    unlock_user(tramp, sigtramp_page, 8);
+}
diff --git a/linux-user/riscv/target_signal.h b/linux-user/riscv/target_signal.h
index f113ba9a55f6..3e36fddc9dbb 100644
--- a/linux-user/riscv/target_signal.h
+++ b/linux-user/riscv/target_signal.h
@@ -15,4 +15,6 @@  typedef struct target_sigaltstack {
 
 #include "../generic/signal.h"
 
+#define TARGET_ARCH_HAS_SIGTRAMP_PAGE 1
+
 #endif /* RISCV_TARGET_SIGNAL_H */