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[PATCH v4 01/25] linux-user: Add infrastructure for a signal trampoline
From: |
Richard Henderson |
Subject: |
[PATCH v4 01/25] linux-user: Add infrastructure for a signal trampoline page |
Date: |
Mon, 27 Sep 2021 22:00:15 -0400 |
Allocate a page to hold the signal trampoline(s).
Invoke a guest-specific hook to fill in the contents
of the page before marking it read-execute again.
Reviewed-by: Max Filippov <jcmvbkbc@gmail.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
linux-user/signal-common.h | 6 ++++++
linux-user/elfload.c | 18 ++++++++++++++++++
linux-user/signal.c | 3 +++
3 files changed, 27 insertions(+)
diff --git a/linux-user/signal-common.h b/linux-user/signal-common.h
index 79511becb4..7457f8025c 100644
--- a/linux-user/signal-common.h
+++ b/linux-user/signal-common.h
@@ -20,6 +20,12 @@
#ifndef SIGNAL_COMMON_H
#define SIGNAL_COMMON_H
+/* Fallback addresses into sigtramp page. */
+extern abi_ulong default_sigreturn;
+extern abi_ulong default_rt_sigreturn;
+
+void setup_sigtramp(abi_ulong tramp_page);
+
int on_sig_stack(unsigned long sp);
int sas_ss_flags(unsigned long sp);
abi_ulong target_sigsp(abi_ulong sp, struct target_sigaction *ka);
diff --git a/linux-user/elfload.c b/linux-user/elfload.c
index 5f9e2141ad..459a26ef1d 100644
--- a/linux-user/elfload.c
+++ b/linux-user/elfload.c
@@ -7,6 +7,7 @@
#include "qemu.h"
#include "user-internals.h"
+#include "signal-common.h"
#include "loader.h"
#include "user-mmap.h"
#include "disas/disas.h"
@@ -17,6 +18,7 @@
#include "qemu/units.h"
#include "qemu/selfmap.h"
#include "qapi/error.h"
+#include "target_signal.h"
#ifdef _ARCH_PPC64
#undef ARCH_DLINFO
@@ -28,6 +30,10 @@
#undef ELF_ARCH
#endif
+#ifndef TARGET_ARCH_HAS_SIGTRAMP_PAGE
+#define TARGET_ARCH_HAS_SIGTRAMP_PAGE 0
+#endif
+
#define ELF_OSABI ELFOSABI_SYSV
/* from personality.h */
@@ -3249,6 +3255,18 @@ int load_elf_binary(struct linux_binprm *bprm, struct
image_info *info)
#endif
}
+ /*
+ * TODO: load a vdso, which would also contain the signal trampolines.
+ * Otherwise, allocate a private page to hold them.
+ */
+ if (TARGET_ARCH_HAS_SIGTRAMP_PAGE) {
+ abi_ulong tramp_page = target_mmap(0, TARGET_PAGE_SIZE,
+ PROT_READ | PROT_WRITE,
+ MAP_PRIVATE | MAP_ANON, -1, 0);
+ setup_sigtramp(tramp_page);
+ target_mprotect(tramp_page, TARGET_PAGE_SIZE, PROT_READ | PROT_EXEC);
+ }
+
bprm->p = create_elf_tables(bprm->p, bprm->argc, bprm->envc, &elf_ex,
info, (elf_interpreter ? &interp_info : NULL));
info->start_stack = bprm->p;
diff --git a/linux-user/signal.c b/linux-user/signal.c
index 2038216455..14d8fdfde1 100644
--- a/linux-user/signal.c
+++ b/linux-user/signal.c
@@ -35,6 +35,9 @@ static struct target_sigaction sigact_table[TARGET_NSIG];
static void host_signal_handler(int host_signum, siginfo_t *info,
void *puc);
+/* Fallback addresses into sigtramp page. */
+abi_ulong default_sigreturn;
+abi_ulong default_rt_sigreturn;
/*
* System includes define _NSIG as SIGRTMAX + 1,
--
2.25.1
- [PATCH v4 00/25] linux-user: Move signal trampolines to new page, Richard Henderson, 2021/09/27
- [PATCH v4 06/25] linux-user/alpha: Implement setup_sigtramp, Richard Henderson, 2021/09/27
- [PATCH v4 03/25] linux-user/arm: Drop v1 signal frames, Richard Henderson, 2021/09/27
- [PATCH v4 05/25] linux-user/arm: Implement setup_sigtramp, Richard Henderson, 2021/09/27
- [PATCH v4 02/25] linux-user/aarch64: Implement setup_sigtramp, Richard Henderson, 2021/09/27
- [PATCH v4 01/25] linux-user: Add infrastructure for a signal trampoline page,
Richard Henderson <=
- [PATCH v4 11/25] linux-user/x86_64: Raise SIGSEGV if SA_RESTORER not set, Richard Henderson, 2021/09/27
- [PATCH v4 10/25] linux-user/i386: Implement setup_sigtramp, Richard Henderson, 2021/09/27
- [PATCH v4 14/25] linux-user/mips: Tidy install_sigtramp, Richard Henderson, 2021/09/27
- [PATCH v4 12/25] linux-user/m68k: Implement setup_sigtramp, Richard Henderson, 2021/09/27
- [PATCH v4 16/25] linux-user/nios2: Document non-use of setup_sigtramp, Richard Henderson, 2021/09/27
- [PATCH v4 18/25] linux-user/ppc: Simplify encode_trampoline, Richard Henderson, 2021/09/27
- [PATCH v4 07/25] linux-user/cris: Implement setup_sigtramp, Richard Henderson, 2021/09/27
- [PATCH v4 09/25] linux-user/hppa: Document non-use of setup_sigtramp, Richard Henderson, 2021/09/27