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| author | Johannes Berg <johannes.berg@intel.com> | 2025-02-10 19:09:25 +0300 |
|---|---|---|
| committer | Johannes Berg <johannes.berg@intel.com> | 2025-03-18 13:03:14 +0300 |
| commit | d1d7f01f7cd35e16c6bcef5a0e31988b5c9980f9 (patch) | |
| tree | ac2a7b2c4ccc6a9f1749c48eca519d615d125942 /arch/um/include/shared/kern_util.h | |
| parent | 5550187c4c21740942c32a9ae56f9f472a104cb4 (diff) | |
| download | linux-d1d7f01f7cd35e16c6bcef5a0e31988b5c9980f9.tar.xz | |
um: mark rodata read-only and implement _nofault accesses
Mark read-only data actually read-only (simple mprotect), and
to be able to test it also implement _nofault accesses. This
works by setting up a new "segv_continue" pointer in current,
and then when we hit a segfault we change the signal return
context so that we continue at that address. The code using
this sets it up so that it jumps to a label and then aborts
the access that way, returning -EFAULT.
It's possible to optimize the ___backtrack_faulted() thing by
using asm goto (compiler version dependent) and/or gcc's (not
sure if clang has it) &&label extension, but at least in one
attempt I made the && caused the compiler to not load -EFAULT
into the register in case of jumping to the &&label from the
fault handler. So leave it like this for now.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Co-developed-by: Benjamin Berg <benjamin.berg@intel.com>
Signed-off-by: Benjamin Berg <benjamin.berg@intel.com>
Link: https://patch.msgid.link/20250210160926.420133-2-benjamin@sipsolutions.net
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Diffstat (limited to 'arch/um/include/shared/kern_util.h')
| -rw-r--r-- | arch/um/include/shared/kern_util.h | 12 |
1 files changed, 8 insertions, 4 deletions
diff --git a/arch/um/include/shared/kern_util.h b/arch/um/include/shared/kern_util.h index f21dc8517538..00ca3e12fd9a 100644 --- a/arch/um/include/shared/kern_util.h +++ b/arch/um/include/shared/kern_util.h @@ -24,10 +24,12 @@ extern void free_stack(unsigned long stack, int order); struct pt_regs; extern void do_signal(struct pt_regs *regs); extern void interrupt_end(void); -extern void relay_signal(int sig, struct siginfo *si, struct uml_pt_regs *regs); +extern void relay_signal(int sig, struct siginfo *si, struct uml_pt_regs *regs, + void *mc); extern unsigned long segv(struct faultinfo fi, unsigned long ip, - int is_user, struct uml_pt_regs *regs); + int is_user, struct uml_pt_regs *regs, + void *mc); extern int handle_page_fault(unsigned long address, unsigned long ip, int is_write, int is_user, int *code_out); @@ -59,8 +61,10 @@ extern unsigned long from_irq_stack(int nested); extern int singlestepping(void); -extern void segv_handler(int sig, struct siginfo *unused_si, struct uml_pt_regs *regs); -extern void winch(int sig, struct siginfo *unused_si, struct uml_pt_regs *regs); +extern void segv_handler(int sig, struct siginfo *unused_si, struct uml_pt_regs *regs, + void *mc); +extern void winch(int sig, struct siginfo *unused_si, struct uml_pt_regs *regs, + void *mc); extern void fatal_sigsegv(void) __attribute__ ((noreturn)); void um_idle_sleep(void); |