mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-29 12:19:39 +00:00
987c426320
read_user_stack_slow that walks user address translation by hand is only required on hash, because a hash fault can not be serviced from "NMI" context (to avoid re-entering the hash code) so the user stack can be mapped into Linux page tables but not accessible by the CPU. Radix MMU mode does not have this restriction. A page fault failure would indicate the page is not accessible via get_user_pages either, so avoid this on radix. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20201111120151.3150658-1-npiggin@gmail.com
42 lines
1.2 KiB
C
42 lines
1.2 KiB
C
/* SPDX-License-Identifier: GPL-2.0-or-later */
|
|
#ifndef _POWERPC_PERF_CALLCHAIN_H
|
|
#define _POWERPC_PERF_CALLCHAIN_H
|
|
|
|
int read_user_stack_slow(const void __user *ptr, void *buf, int nb);
|
|
void perf_callchain_user_64(struct perf_callchain_entry_ctx *entry,
|
|
struct pt_regs *regs);
|
|
void perf_callchain_user_32(struct perf_callchain_entry_ctx *entry,
|
|
struct pt_regs *regs);
|
|
|
|
static inline bool invalid_user_sp(unsigned long sp)
|
|
{
|
|
unsigned long mask = is_32bit_task() ? 3 : 7;
|
|
unsigned long top = STACK_TOP - (is_32bit_task() ? 16 : 32);
|
|
|
|
return (!sp || (sp & mask) || (sp > top));
|
|
}
|
|
|
|
/*
|
|
* On 32-bit we just access the address and let hash_page create a
|
|
* HPTE if necessary, so there is no need to fall back to reading
|
|
* the page tables. Since this is called at interrupt level,
|
|
* do_page_fault() won't treat a DSI as a page fault.
|
|
*/
|
|
static inline int __read_user_stack(const void __user *ptr, void *ret,
|
|
size_t size)
|
|
{
|
|
unsigned long addr = (unsigned long)ptr;
|
|
int rc;
|
|
|
|
if (addr > TASK_SIZE - size || (addr & (size - 1)))
|
|
return -EFAULT;
|
|
|
|
rc = copy_from_user_nofault(ret, ptr, size);
|
|
|
|
if (IS_ENABLED(CONFIG_PPC64) && !radix_enabled() && rc)
|
|
return read_user_stack_slow(ptr, ret, size);
|
|
|
|
return rc;
|
|
}
|
|
|
|
#endif /* _POWERPC_PERF_CALLCHAIN_H */
|