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powerpc/mm: Move the WARN() out of bad_kuap_fault() 

In order to prepare the removal of calls to
search_exception_tables() on the fast path, move the
WARN() out of bad_kuap_fault().

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/9501311014bd6507e04b27a0c3035186ccf65cd5.1607491748.git.christophe.leroy@csgroup.eu
This commit is contained in:
Christophe Leroy 2020-12-09 05:29:23 +00:00 committed by Michael Ellerman
parent 5250d026d2
commit 3dc12dfe74
4 changed files with 5 additions and 12 deletions
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6
arch/powerpc/include/asm/book3s/32/kup.h
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@ -183,11 +183,7 @@ bad_kuap_fault(struct pt_regs *regs, unsigned long address, bool is_write)
unsigned long begin = regs->kuap & 0xf0000000;
unsigned long end = regs->kuap << 28;
if (!is_write)
return false;
return WARN(address < begin || address >= end,
"Bug: write fault blocked by segment registers !");
return is_write && (address < begin || address >= end);
}
#endif /* CONFIG_PPC_KUAP */

6
arch/powerpc/include/asm/book3s/64/kup.h
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@ -371,11 +371,9 @@ static inline bool bad_kuap_fault(struct pt_regs *regs, unsigned long address,
* the AMR. Hence check for BLOCK_WRITE/READ against AMR.
*/
if (is_write) {
return WARN(((regs->amr & AMR_KUAP_BLOCK_WRITE) == AMR_KUAP_BLOCK_WRITE),
"Bug: Write fault blocked by AMR!");
return (regs->amr & AMR_KUAP_BLOCK_WRITE) == AMR_KUAP_BLOCK_WRITE;
}
return WARN(((regs->amr & AMR_KUAP_BLOCK_READ) == AMR_KUAP_BLOCK_READ),
"Bug: Read fault blocked by AMR!");
return (regs->amr & AMR_KUAP_BLOCK_READ) == AMR_KUAP_BLOCK_READ;
}
static __always_inline void allow_user_access(void __user *to, const void __user *from,

3
arch/powerpc/include/asm/nohash/32/kup-8xx.h
View File

@ -63,8 +63,7 @@ static inline void restore_user_access(unsigned long flags)
static inline bool
bad_kuap_fault(struct pt_regs *regs, unsigned long address, bool is_write)
{
return WARN(!((regs->kuap ^ MD_APG_KUAP) & 0xff000000),
"Bug: fault blocked by AP register !");
return !((regs->kuap ^ MD_APG_KUAP) & 0xff000000);
}
#endif /* !__ASSEMBLY__ */

2
arch/powerpc/mm/fault.c
View File

@ -228,7 +228,7 @@ static bool bad_kernel_fault(struct pt_regs *regs, unsigned long error_code,
// Read/write fault in a valid region (the exception table search passed
// above), but blocked by KUAP is bad, it can never succeed.
if (bad_kuap_fault(regs, address, is_write))
return true;
return WARN(true, "Bug: %s fault blocked by KUAP!", is_write ? "Write" : "Read");
// What's left? Kernel fault on user in well defined regions (extable
// matched), and allowed by KUAP in the faulting context.