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 03/15] powerpc/align: Convert emulate_spe() to user_access_begin
Date: Wed, 10 Mar 2021 17:46:42 +0000 (UTC) [thread overview]
Message-ID: <0ad4629c2d222019e82fcdfccc70d372beb4adf9.1615398265.git.christophe.leroy@csgroup.eu> (raw)
In-Reply-To: <cover.1615398265.git.christophe.leroy@csgroup.eu>
This patch converts emulate_spe() to using user_access_being
logic.
Since commit 662bbcb2747c ("mm, sched: Allow uaccess in atomic with
pagefault_disable()"), might_fault() doesn't fire when called from
sections where pagefaults are disabled, which must be the case
when using _inatomic variants of __get_user and __put_user. So
the might_fault() in user_access_begin() is not a problem.
There was a verification of user_mode() together with the access_ok(),
but the function returns in case !user_mode() immediately after
the access_ok() verification, so removing that test has no effect.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
arch/powerpc/kernel/align.c | 61 ++++++++++++++++++++-----------------
1 file changed, 33 insertions(+), 28 deletions(-)
diff --git a/arch/powerpc/kernel/align.c b/arch/powerpc/kernel/align.c
index c7797eb958c7..c4d7b445b459 100644
--- a/arch/powerpc/kernel/align.c
+++ b/arch/powerpc/kernel/align.c
@@ -107,7 +107,6 @@ static struct aligninfo spe_aligninfo[32] = {
static int emulate_spe(struct pt_regs *regs, unsigned int reg,
struct ppc_inst ppc_instr)
{
- int ret;
union {
u64 ll;
u32 w[2];
@@ -127,11 +126,6 @@ static int emulate_spe(struct pt_regs *regs, unsigned int reg,
nb = spe_aligninfo[instr].len;
flags = spe_aligninfo[instr].flags;
- /* Verify the address of the operand */
- if (unlikely(user_mode(regs) &&
- !access_ok(addr, nb)))
- return -EFAULT;
-
/* userland only */
if (unlikely(!user_mode(regs)))
return 0;
@@ -169,26 +163,27 @@ static int emulate_spe(struct pt_regs *regs, unsigned int reg,
}
} else {
temp.ll = data.ll = 0;
- ret = 0;
p = addr;
+ if (!user_read_access_begin(addr, nb))
+ return -EFAULT;
+
switch (nb) {
case 8:
- ret |= __get_user_inatomic(temp.v[0], p++);
- ret |= __get_user_inatomic(temp.v[1], p++);
- ret |= __get_user_inatomic(temp.v[2], p++);
- ret |= __get_user_inatomic(temp.v[3], p++);
+ unsafe_get_user(temp.v[0], p++, Efault_read);
+ unsafe_get_user(temp.v[1], p++, Efault_read);
+ unsafe_get_user(temp.v[2], p++, Efault_read);
+ unsafe_get_user(temp.v[3], p++, Efault_read);
fallthrough;
case 4:
- ret |= __get_user_inatomic(temp.v[4], p++);
- ret |= __get_user_inatomic(temp.v[5], p++);
+ unsafe_get_user(temp.v[4], p++, Efault_read);
+ unsafe_get_user(temp.v[5], p++, Efault_read);
fallthrough;
case 2:
- ret |= __get_user_inatomic(temp.v[6], p++);
- ret |= __get_user_inatomic(temp.v[7], p++);
- if (unlikely(ret))
- return -EFAULT;
+ unsafe_get_user(temp.v[6], p++, Efault_read);
+ unsafe_get_user(temp.v[7], p++, Efault_read);
}
+ user_read_access_end();
switch (instr) {
case EVLDD:
@@ -255,31 +250,41 @@ static int emulate_spe(struct pt_regs *regs, unsigned int reg,
/* Store result to memory or update registers */
if (flags & ST) {
- ret = 0;
p = addr;
+
+ if (!user_read_access_begin(addr, nb))
+ return -EFAULT;
+
switch (nb) {
case 8:
- ret |= __put_user_inatomic(data.v[0], p++);
- ret |= __put_user_inatomic(data.v[1], p++);
- ret |= __put_user_inatomic(data.v[2], p++);
- ret |= __put_user_inatomic(data.v[3], p++);
+ unsafe_put_user(data.v[0], p++, Efault_write);
+ unsafe_put_user(data.v[1], p++, Efault_write);
+ unsafe_put_user(data.v[2], p++, Efault_write);
+ unsafe_put_user(data.v[3], p++, Efault_write);
fallthrough;
case 4:
- ret |= __put_user_inatomic(data.v[4], p++);
- ret |= __put_user_inatomic(data.v[5], p++);
+ unsafe_put_user(data.v[4], p++, Efault_write);
+ unsafe_put_user(data.v[5], p++, Efault_write);
fallthrough;
case 2:
- ret |= __put_user_inatomic(data.v[6], p++);
- ret |= __put_user_inatomic(data.v[7], p++);
+ unsafe_put_user(data.v[6], p++, Efault_write);
+ unsafe_put_user(data.v[7], p++, Efault_write);
}
- if (unlikely(ret))
- return -EFAULT;
+ user_write_access_end();
} else {
*evr = data.w[0];
regs->gpr[reg] = data.w[1];
}
return 1;
+
+Efault_read:
+ user_read_access_end();
+ return -EFAULT;
+
+Efault_write:
+ user_write_access_end();
+ return -EFAULT;
}
#endif /* CONFIG_SPE */
--
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 ` Christophe Leroy [this message]
2021-03-10 22:31 ` [PATCH v2 03/15] powerpc/align: Convert emulate_spe() to user_access_begin 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 ` [PATCH v2 06/15] powerpc/align: Don't use __get_user_instr() on kernel addresses Christophe Leroy
2021-03-25 22:12 ` 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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