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linux-user/hppa: Allocate page zero as a commpage

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We're about to start validating PAGE_EXEC, which means that we've
got to mark page zero executable.  We had been special casing this
entirely within translate.

Acked-by: Ilya Leoshkevich <iii@linux.ibm.com>
Tested-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This commit is contained in:
Richard Henderson 2022-08-10 18:44:48 -07:00
parent fbd3c4cff6
commit eee816c0b9
1 changed files with 31 additions and 3 deletions
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34
linux-user/elfload.c
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@ -1646,6 +1646,34 @@ static inline void init_thread(struct target_pt_regs *regs,
regs->gr[31] = infop->entry;
}
#define LO_COMMPAGE 0
static bool init_guest_commpage(void)
{
void *want = g2h_untagged(LO_COMMPAGE);
void *addr = mmap(want, qemu_host_page_size, PROT_NONE,
MAP_ANONYMOUS | MAP_PRIVATE | MAP_FIXED, -1, 0);
if (addr == MAP_FAILED) {
perror("Allocating guest commpage");
exit(EXIT_FAILURE);
}
if (addr != want) {
return false;
}
/*
* On Linux, page zero is normally marked execute only + gateway.
* Normal read or write is supposed to fail (thus PROT_NONE above),
* but specific offsets have kernel code mapped to raise permissions
* and implement syscalls. Here, simply mark the page executable.
* Special case the entry points during translation (see do_page_zero).
*/
page_set_flags(LO_COMMPAGE, LO_COMMPAGE + TARGET_PAGE_SIZE,
PAGE_EXEC | PAGE_VALID);
return true;
}
#endif /* TARGET_HPPA */
#ifdef TARGET_XTENSA
@ -2326,12 +2354,12 @@ static abi_ulong create_elf_tables(abi_ulong p, int argc, int envc,
}
#if defined(HI_COMMPAGE)
#define LO_COMMPAGE 0
#define LO_COMMPAGE -1
#elif defined(LO_COMMPAGE)
#define HI_COMMPAGE 0
#else
#define HI_COMMPAGE 0
#define LO_COMMPAGE 0
#define LO_COMMPAGE -1
#define init_guest_commpage() true
#endif
@ -2555,7 +2583,7 @@ static void pgb_static(const char *image_name, abi_ulong orig_loaddr,
} else {
offset = -(HI_COMMPAGE & -align);
}
} else if (LO_COMMPAGE != 0) {
} else if (LO_COMMPAGE != -1) {
loaddr = MIN(loaddr, LO_COMMPAGE & -align);
}