From: Christophe Leroy <christophe.leroy@csgroup.eu>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
Michael Ellerman <mpe@ellerman.id.au>
Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Subject: [PATCH v2 06/15] powerpc/align: Don't use __get_user_instr() on kernel addresses
Date: Wed, 10 Mar 2021 17:46:45 +0000 (UTC) [thread overview]
Message-ID: <d9ecbce00178484e66ca7adec2ff210058037704.1615398265.git.christophe.leroy@csgroup.eu> (raw)
In-Reply-To: <cover.1615398265.git.christophe.leroy@csgroup.eu>
In the old days, when we didn't have kernel userspace access
protection and had set_fs(), it was wise to use __get_user()
and friends to read kernel memory.
Nowadays, get_user() is granting userspace access and is exclusively
for userspace access.
In alignment exception handler, use probe_kernel_read_inst()
instead of __get_user_instr() for reading instructions in kernel.
This will allow to remove the is_kernel_addr() check in
__get/put_user() in a following patch.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
arch/powerpc/kernel/align.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/kernel/align.c b/arch/powerpc/kernel/align.c
index c4d7b445b459..8d4c7af262e2 100644
--- a/arch/powerpc/kernel/align.c
+++ b/arch/powerpc/kernel/align.c
@@ -310,7 +310,11 @@ int fix_alignment(struct pt_regs *regs)
*/
CHECK_FULL_REGS(regs);
- if (unlikely(__get_user_instr(instr, (void __user *)regs->nip)))
+ if (is_kernel_addr(regs->nip))
+ r = probe_kernel_read_inst(&instr, (void *)regs->nip);
+ else
+ r = __get_user_instr(instr, (void __user *)regs->nip);
+ if (unlikely(r))
return -EFAULT;
if ((regs->msr & MSR_LE) != (MSR_KERNEL & MSR_LE)) {
/* We don't handle PPC little-endian any more... */
--
2.25.0
next prev parent reply other threads:[~2021-03-10 17:47 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-10 17:46 [PATCH v2 00/15] powerpc: Cleanup of uaccess.h and adding asm goto for get_user() Christophe Leroy
2021-03-10 17:46 ` [PATCH v2 01/15] powerpc/uaccess: Remove __get_user_allowed() and unsafe_op_wrap() Christophe Leroy
2021-03-10 21:47 ` Daniel Axtens
2021-03-10 17:46 ` [PATCH v2 02/15] powerpc/uaccess: Define ___get_user_instr() for ppc32 Christophe Leroy
2021-03-10 17:46 ` [PATCH v2 03/15] powerpc/align: Convert emulate_spe() to user_access_begin Christophe Leroy
2021-03-10 22:31 ` Daniel Axtens
2021-03-11 5:45 ` Christophe Leroy
2021-03-12 13:25 ` [PATCH v3 " Christophe Leroy
2021-04-10 14:28 ` Michael Ellerman
2021-03-10 17:46 ` [PATCH v2 04/15] powerpc/uaccess: Remove __get/put_user_inatomic() Christophe Leroy
2021-03-10 22:37 ` Daniel Axtens
2021-03-10 17:46 ` [PATCH v2 05/15] powerpc/uaccess: Move get_user_instr helpers in asm/inst.h Christophe Leroy
2021-03-25 21:59 ` Daniel Axtens
2021-03-10 17:46 ` Christophe Leroy [this message]
2021-03-25 22:12 ` [PATCH v2 06/15] powerpc/align: Don't use __get_user_instr() on kernel addresses Daniel Axtens
2021-03-10 17:46 ` [PATCH v2 07/15] powerpc/uaccess: Call might_fault() inconditionaly Christophe Leroy
2021-03-25 22:38 ` Daniel Axtens
2021-03-25 22:44 ` Daniel Axtens
2021-03-10 17:46 ` [PATCH v2 08/15] powerpc/uaccess: Remove __unsafe_put_user_goto() Christophe Leroy
2021-03-10 17:46 ` [PATCH v2 09/15] powerpc/uaccess: Remove __chk_user_ptr() in __get/put_user Christophe Leroy
2021-03-10 17:46 ` [PATCH v2 10/15] powerpc/uaccess: Remove calls to __get_user_bad() and __put_user_bad() Christophe Leroy
2021-03-10 17:46 ` [PATCH v2 11/15] powerpc/uaccess: Split out __get_user_nocheck() Christophe Leroy
2021-03-10 17:46 ` [PATCH v2 12/15] powerpc/uaccess: Rename __get/put_user_check/nocheck Christophe Leroy
2021-03-10 17:46 ` [PATCH v2 13/15] powerpc/uaccess: Refactor get/put_user() and __get/put_user() Christophe Leroy
2021-03-10 17:46 ` [PATCH v2 14/15] powerpc/uaccess: Introduce __get_user_size_goto() Christophe Leroy
2021-03-10 17:46 ` [PATCH v2 15/15] powerpc/uaccess: Use asm goto for get_user when compiler supports it Christophe Leroy
2021-04-10 14:28 ` [PATCH v2 00/15] powerpc: Cleanup of uaccess.h and adding asm goto for get_user() Michael Ellerman
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