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linux-user/riscv: Implement setup_sigtramp 

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>
This commit is contained in:
Richard Henderson 2021-09-29 09:05:47 -04:00 committed by Laurent Vivier
parent c790e4ebfe
commit 3c62b5d201
2 changed files with 15 additions and 9 deletions
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22
linux-user/riscv/signal.c
View File

@ -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);
}

2
linux-user/riscv/target_signal.h
View File

@ -15,4 +15,6 @@ typedef struct target_sigaltstack {
#include "../generic/signal.h"
#define TARGET_ARCH_HAS_SIGTRAMP_PAGE 1
#endif /* RISCV_TARGET_SIGNAL_H */