[PATCH v3 1/7] arm64: Factor out PAN enabling/disabling into separate uaccess_* macros
From: mark.rutland@arm.com (Mark Rutland)
Date: 2016-09-15 15:10:45
Hi Catalin, On Tue, Sep 13, 2016 at 06:46:31PM +0100, Catalin Marinas wrote:
This patch moves the directly coded alternatives for turning PAN on/off
into separate uaccess_{enable,disable} macros or functions. The asm
macros take a few arguments which will be used in subsequent patches.
Note that any (unlikely) access that the compiler might generate between
uaccess_enable() and uaccess_disable(), other than those explicitly
specified by the user access code, will not be protected by PAN.There's one missing include that I've noted below, along with a number we can now drop. Otherwise, the important parts all look good to me. With the includes fixed up: Reviewed-by: Mark Rutland <mark.rutland@arm.com> [...]
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Cc: Will Deacon <redacted> Cc: James Morse <james.morse@arm.com> Cc: Kees Cook <redacted> Cc: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> --- arch/arm64/include/asm/futex.h | 14 +++---- arch/arm64/include/asm/uaccess.h | 79 ++++++++++++++++++++++++++++++++---- arch/arm64/kernel/armv8_deprecated.c | 10 ++--- arch/arm64/lib/clear_user.S | 8 ++-- arch/arm64/lib/copy_from_user.S | 8 ++-- arch/arm64/lib/copy_in_user.S | 8 ++-- arch/arm64/lib/copy_to_user.S | 8 ++-- 7 files changed, 95 insertions(+), 40 deletions(-)diff --git a/arch/arm64/include/asm/futex.h b/arch/arm64/include/asm/futex.h index f2585cdd32c2..71dfa3b42313 100644 --- a/arch/arm64/include/asm/futex.h +++ b/arch/arm64/include/asm/futex.h@@ -27,9 +27,9 @@ #include <asm/sysreg.h> #define __futex_atomic_op(insn, ret, oldval, uaddr, tmp, oparg) \ +do { \ + uaccess_enable(); \ asm volatile( \ - ALTERNATIVE("nop", SET_PSTATE_PAN(0), ARM64_HAS_PAN, \ - CONFIG_ARM64_PAN) \ " prfm pstl1strm, %2\n" \ "1: ldxr %w1, %2\n" \ insn "\n" \@@ -44,11 +44,11 @@ " .popsection\n" \ _ASM_EXTABLE(1b, 4b) \ _ASM_EXTABLE(2b, 4b) \ - ALTERNATIVE("nop", SET_PSTATE_PAN(1), ARM64_HAS_PAN, \ - CONFIG_ARM64_PAN) \ : "=&r" (ret), "=&r" (oldval), "+Q" (*uaddr), "=&r" (tmp) \ : "r" (oparg), "Ir" (-EFAULT) \ - : "memory") + : "memory"); \ + uaccess_disable(); \ +} while (0)
With the uaccess_{enable,disable}* macros, we can drop the includes for
<asm/alternative.h>, <asm/cpufeature.h>, and <asm/sysreg.h> from
futex.h, as we no longer (directly) use anything from those.
[...]
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diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h index c47257c91b77..cc6c32d4dcc4 100644 --- a/arch/arm64/include/asm/uaccess.h +++ b/arch/arm64/include/asm/uaccess.h
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@@ -321,4 +357,31 @@ extern long strncpy_from_user(char *dest, const char __user *src, long count); extern __must_check long strlen_user(const char __user *str); extern __must_check long strnlen_user(const char __user *str, long n); +#else /* __ASSEMBLY__ */ + +#include <asm/alternative.h> +#include <asm/assembler.h>
We also need <asm/sysreg.h> for SET_PSTATE_PAN() Given we use that and <asm/alternative.h> either way, should we pull those above the #ifdef __ASSEMBLY__? I have no feeling either way. [...]
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diff --git a/arch/arm64/kernel/armv8_deprecated.c b/arch/arm64/kernel/armv8_deprecated.c index 42ffdb54e162..7156e7bfcd89 100644 --- a/arch/arm64/kernel/armv8_deprecated.c +++ b/arch/arm64/kernel/armv8_deprecated.c@@ -281,9 +281,9 @@ static void __init register_insn_emulation_sysctl(struct ctl_table *table) * Error-checking SWP macros implemented using ldxr{b}/stxr{b} */ #define __user_swpX_asm(data, addr, res, temp, B) \ +do { \ + uaccess_enable(); \ __asm__ __volatile__( \ - ALTERNATIVE("nop", SET_PSTATE_PAN(0), ARM64_HAS_PAN, \ - CONFIG_ARM64_PAN) \ "0: ldxr"B" %w2, [%3]\n" \ "1: stxr"B" %w0, %w1, [%3]\n" \ " cbz %w0, 2f\n" \@@ -299,11 +299,11 @@ static void __init register_insn_emulation_sysctl(struct ctl_table *table) " .popsection" \ _ASM_EXTABLE(0b, 4b) \ _ASM_EXTABLE(1b, 4b) \ - ALTERNATIVE("nop", SET_PSTATE_PAN(1), ARM64_HAS_PAN, \ - CONFIG_ARM64_PAN) \ : "=&r" (res), "+r" (data), "=&r" (temp) \ : "r" (addr), "i" (-EAGAIN), "i" (-EFAULT) \ - : "memory") + : "memory"); \ + uaccess_disable(); \ +} while (0)
With this, we can drop the include of <asm/alternative.h>, though unlike futex.h we need to keep <asm/cpufeature.h> and <asm/sysreg.h>. [...]
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diff --git a/arch/arm64/lib/clear_user.S b/arch/arm64/lib/clear_user.S index 5d1cad3ce6d6..08b5f18ba604 100644 --- a/arch/arm64/lib/clear_user.S +++ b/arch/arm64/lib/clear_user.S@@ -17,10 +17,10 @@ */ #include <linux/linkage.h> -#include <asm/alternative.h> #include <asm/assembler.h> #include <asm/cpufeature.h> #include <asm/sysreg.h> +#include <asm/uaccess.h>
As with futex.h, we can drop <asm/assembler.h>, <asm/cpufeature.h>, and
<asm/sysreg.h>, as the uaccess_{enable,disable}* macros mean we no
longer use anything from those directly.
[...]
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diff --git a/arch/arm64/lib/copy_from_user.S b/arch/arm64/lib/copy_from_user.S index 0b90497d4424..6505ec81f1da 100644 --- a/arch/arm64/lib/copy_from_user.S +++ b/arch/arm64/lib/copy_from_user.S@@ -16,11 +16,11 @@ #include <linux/linkage.h> -#include <asm/alternative.h> #include <asm/assembler.h> #include <asm/cache.h> #include <asm/cpufeature.h> #include <asm/sysreg.h> +#include <asm/uaccess.h>
Likewise, we can also drop <asm/assembler.h>, <asm/cpufeature.h>, and <asm/sysreg.h> here. [...]
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diff --git a/arch/arm64/lib/copy_in_user.S b/arch/arm64/lib/copy_in_user.S index f7292dd08c84..9b04ff3ab610 100644 --- a/arch/arm64/lib/copy_in_user.S +++ b/arch/arm64/lib/copy_in_user.S@@ -18,11 +18,11 @@ #include <linux/linkage.h> -#include <asm/alternative.h> #include <asm/assembler.h> #include <asm/cache.h> #include <asm/cpufeature.h> #include <asm/sysreg.h> +#include <asm/uaccess.h>
Likewise, we can also drop <asm/assembler.h>, <asm/cpufeature.h>, and <asm/sysreg.h> here. [...]
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diff --git a/arch/arm64/lib/copy_to_user.S b/arch/arm64/lib/copy_to_user.S index 7a7efe255034..8077e4f34d56 100644 --- a/arch/arm64/lib/copy_to_user.S +++ b/arch/arm64/lib/copy_to_user.S@@ -16,11 +16,11 @@ #include <linux/linkage.h> -#include <asm/alternative.h> #include <asm/assembler.h> #include <asm/cache.h> #include <asm/cpufeature.h> #include <asm/sysreg.h> +#include <asm/uaccess.h>
Likewise, we can also drop <asm/assembler.h>, <asm/cpufeature.h>, and <asm/sysreg.h> here. Thanks, Mark.