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[PATCH v6 03/21] linux-user/x86_64: Allocate vsyscall page as a commpage
From: |
Richard Henderson |
Subject: |
[PATCH v6 03/21] linux-user/x86_64: Allocate vsyscall page as a commpage |
Date: |
Thu, 18 Aug 2022 20:25:57 -0700 |
We're about to start validating PAGE_EXEC, which means that we've
got to the vsyscall page executable. We had been special casing
this entirely within translate.
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
linux-user/elfload.c | 23 +++++++++++++++++++++++
1 file changed, 23 insertions(+)
diff --git a/linux-user/elfload.c b/linux-user/elfload.c
index 29d910c4cc..b20d513929 100644
--- a/linux-user/elfload.c
+++ b/linux-user/elfload.c
@@ -195,6 +195,27 @@ static void elf_core_copy_regs(target_elf_gregset_t *regs,
const CPUX86State *en
(*regs)[26] = tswapreg(env->segs[R_GS].selector & 0xffff);
}
+#if ULONG_MAX >= TARGET_VSYSCALL_PAGE
+#define INIT_GUEST_COMMPAGE
+static bool init_guest_commpage(void)
+{
+ /*
+ * The vsyscall page is at a high negative address aka kernel space,
+ * which means that we cannot actually allocate it with target_mmap.
+ * We still should be able to use page_set_flags, unless the user
+ * has specified -R reserved_va, which would trigger an assert().
+ */
+ if (reserved_va != 0 &&
+ TARGET_VSYSCALL_PAGE + TARGET_PAGE_SIZE >= reserved_va) {
+ error_report("Cannot allocate vsyscall page");
+ exit(EXIT_FAILURE);
+ }
+ page_set_flags(TARGET_VSYSCALL_PAGE,
+ TARGET_VSYSCALL_PAGE + TARGET_PAGE_SIZE,
+ PAGE_EXEC | PAGE_VALID);
+ return true;
+}
+#endif
#else
#define ELF_START_MMAP 0x80000000
@@ -2360,8 +2381,10 @@ static abi_ulong create_elf_tables(abi_ulong p, int
argc, int envc,
#else
#define HI_COMMPAGE 0
#define LO_COMMPAGE -1
+#ifndef INIT_GUEST_COMMPAGE
#define init_guest_commpage() true
#endif
+#endif
static void pgb_fail_in_use(const char *image_name)
{
--
2.34.1
- [PATCH v6 00/21] linux-user: Fix siginfo_t contents when jumping to non-readable pages, Richard Henderson, 2022/08/18
- [PATCH v6 02/21] linux-user/hppa: Allocate page zero as a commpage, Richard Henderson, 2022/08/18
- [PATCH v6 01/21] linux-user/arm: Mark the commpage executable, Richard Henderson, 2022/08/18
- [PATCH v6 03/21] linux-user/x86_64: Allocate vsyscall page as a commpage,
Richard Henderson <=
- [PATCH v6 05/21] linux-user: Clear translations and tb_jmp_cache on mprotect(), Richard Henderson, 2022/08/18
- [PATCH v6 04/21] linux-user: Honor PT_GNU_STACK, Richard Henderson, 2022/08/18
- [PATCH v6 06/21] tests/tcg/i386: Move smc_code2 to an executable section, Richard Henderson, 2022/08/18
- [PATCH v6 07/21] accel/tcg: Introduce is_same_page(), Richard Henderson, 2022/08/18
- [PATCH v6 09/21] accel/tcg: Unlock mmap_lock after longjmp, Richard Henderson, 2022/08/18
- [PATCH v6 11/21] accel/tcg: Move qemu_ram_addr_from_host_nofail to physmem.c, Richard Henderson, 2022/08/18
- [PATCH v6 13/21] accel/tcg: Add nofault parameter to get_page_addr_code_hostp, Richard Henderson, 2022/08/18