Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
powerpc/book3s64/kuap: Improve error reporting with KUAP
With hash translation use DSISR_KEYFAULT to identify a wrong access.
With Radix we look at the AMR value and type of fault.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20201127044424.40686-17-aneesh.kumar@linux.ibm.com
authored by
Aneesh Kumar K.V
and committed by
Michael Ellerman
eb232b16
4d6c551e
+29
-12
+2
-2
arch/powerpc/include/asm/book3s/32/kup.h
+2
-2
arch/powerpc/include/asm/book3s/32/kup.h
···
177
177
allow_user_access(to, to, end - addr, KUAP_READ_WRITE);
178
178
}
179
179
180
-
static inline bool
181
-
bad_kuap_fault(struct pt_regs *regs, unsigned long address, bool is_write)
180
+
static inline bool bad_kuap_fault(struct pt_regs *regs, unsigned long address,
181
+
bool is_write, unsigned long error_code)
182
182
{
183
183
unsigned long begin = regs->kuap & 0xf0000000;
184
184
unsigned long end = regs->kuap << 28;
+22
-5
arch/powerpc/include/asm/book3s/64/kup.h
+22
-5
arch/powerpc/include/asm/book3s/64/kup.h
···
303
303
isync();
304
304
}
305
305
306
-
static inline bool
307
-
bad_kuap_fault(struct pt_regs *regs, unsigned long address, bool is_write)
306
+
#define RADIX_KUAP_BLOCK_READ UL(0x4000000000000000)
307
+
#define RADIX_KUAP_BLOCK_WRITE UL(0x8000000000000000)
308
+
309
+
static inline bool bad_kuap_fault(struct pt_regs *regs, unsigned long address,
310
+
bool is_write, unsigned long error_code)
308
311
{
309
-
return WARN(mmu_has_feature(MMU_FTR_BOOK3S_KUAP) &&
310
-
(regs->kuap & (is_write ? AMR_KUAP_BLOCK_WRITE : AMR_KUAP_BLOCK_READ)),
311
-
"Bug: %s fault blocked by AMR!", is_write ? "Write" : "Read");
312
+
if (!mmu_has_feature(MMU_FTR_BOOK3S_KUAP))
313
+
return false;
314
+
315
+
if (radix_enabled()) {
316
+
/*
317
+
* Will be a storage protection fault.
318
+
* Only check the details of AMR[0]
319
+
*/
320
+
return WARN((regs->kuap & (is_write ? RADIX_KUAP_BLOCK_WRITE : RADIX_KUAP_BLOCK_READ)),
321
+
"Bug: %s fault blocked by AMR!", is_write ? "Write" : "Read");
322
+
}
323
+
/*
324
+
* We don't want to WARN here because userspace can setup
325
+
* keys such that a kernel access to user address can cause
326
+
* fault
327
+
*/
328
+
return !!(error_code & DSISR_KEYFAULT);
312
329
}
313
330
314
331
static __always_inline void allow_user_access(void __user *to, const void __user *from,
+2
-2
arch/powerpc/include/asm/kup.h
+2
-2
arch/powerpc/include/asm/kup.h
···
59
59
#else
60
60
static inline void setup_kuap(bool disabled) { }
61
61
62
-
static inline bool
63
-
bad_kuap_fault(struct pt_regs *regs, unsigned long address, bool is_write)
62
+
static inline bool bad_kuap_fault(struct pt_regs *regs, unsigned long address,
63
+
bool is_write, unsigned long error_code)
64
64
{
65
65
return false;
66
66
}
+2
-2
arch/powerpc/include/asm/nohash/32/kup-8xx.h
+2
-2
arch/powerpc/include/asm/nohash/32/kup-8xx.h
···
60
60
mtspr(SPRN_MD_AP, flags);
61
61
}
62
62
63
-
static inline bool
64
-
bad_kuap_fault(struct pt_regs *regs, unsigned long address, bool is_write)
63
+
static inline bool bad_kuap_fault(struct pt_regs *regs, unsigned long address,
64
+
bool is_write, unsigned long error_code)
65
65
{
66
66
return WARN(!((regs->kuap ^ MD_APG_KUAP) & 0xff000000),
67
67
"Bug: fault blocked by AP register !");
+1
-1
arch/powerpc/mm/fault.c
+1
-1
arch/powerpc/mm/fault.c
···
227
227
228
228
// Read/write fault in a valid region (the exception table search passed
229
229
// above), but blocked by KUAP is bad, it can never succeed.
230
-
if (bad_kuap_fault(regs, address, is_write))
230
+
if (bad_kuap_fault(regs, address, is_write, error_code))
231
231
return true;
232
232
233
233
// What's left? Kernel fault on user in well defined regions (extable