From: Mark Rutland <mark.rutland@arm.com> To: linux-arm-kernel@lists.infradead.org Cc: arnd@arndb.de, catalin.marinas@arm.com, cdall@kernel.org, drjones@redhat.com, kvmarm@lists.cs.columbia.edu, linux-arch@vger.kernel.org, marc.zyngier@arm.com, mark.rutland@arm.com, ramana.radhakrishnan@arm.com, suzuki.poulose@arm.com, will.deacon@arm.com, linux-kernel@vger.kernel.org, awallis@codeaurora.org, kernel-hardening@lists.openwall.com Subject: [PATCHv3 09/11] arm64: perf: strip PAC when unwinding userspace Date: Tue, 17 Apr 2018 19:37:33 +0100 [thread overview] Message-ID: <20180417183735.56985-10-mark.rutland@arm.com> (raw) In-Reply-To: <20180417183735.56985-1-mark.rutland@arm.com> When the kernel is unwinding userspace callchains, we can't expect that the userspace consumer of these callchains has the data necessary to strip the PAC from the stored LR. This patch has the kernel strip the PAC from user stackframes when the in-kernel unwinder is used. This only affects the LR value, and not the FP. This only affects the in-kernel unwinder. When userspace performs unwinding, it is up to userspace to strip PACs as necessary (which can be determined from DWARF information). Signed-off-by: Mark Rutland <mark.rutland@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Ramana Radhakrishnan <ramana.radhakrishnan@arm.com> Cc: Will Deacon <will.deacon@arm.com> --- arch/arm64/include/asm/pointer_auth.h | 7 +++++++ arch/arm64/kernel/perf_callchain.c | 5 ++++- 2 files changed, 11 insertions(+), 1 deletion(-) diff --git a/arch/arm64/include/asm/pointer_auth.h b/arch/arm64/include/asm/pointer_auth.h index 5ff141245633..a9ad81791c7f 100644 --- a/arch/arm64/include/asm/pointer_auth.h +++ b/arch/arm64/include/asm/pointer_auth.h @@ -79,6 +79,12 @@ static inline void ptrauth_keys_dup(struct ptrauth_keys *old, */ #define ptrauth_pac_mask() GENMASK(54, VA_BITS) +/* Only valid for EL0 TTBR0 instruction pointers */ +static inline unsigned long ptrauth_strip_insn_pac(unsigned long ptr) +{ + return ptr & ~ptrauth_pac_mask(); +} + #define mm_ctx_ptrauth_init(ctx) \ ptrauth_keys_init(&(ctx)->ptrauth_keys) @@ -89,6 +95,7 @@ static inline void ptrauth_keys_dup(struct ptrauth_keys *old, ptrauth_keys_dup(&(oldctx)->ptrauth_keys, &(newctx)->ptrauth_keys) #else +#define ptrauth_strip_insn_pac(lr) (lr) #define mm_ctx_ptrauth_init(ctx) #define mm_ctx_ptrauth_switch(ctx) #define mm_ctx_ptrauth_dup(oldctx, newctx) diff --git a/arch/arm64/kernel/perf_callchain.c b/arch/arm64/kernel/perf_callchain.c index bcafd7dcfe8b..928204f6ab08 100644 --- a/arch/arm64/kernel/perf_callchain.c +++ b/arch/arm64/kernel/perf_callchain.c @@ -35,6 +35,7 @@ user_backtrace(struct frame_tail __user *tail, { struct frame_tail buftail; unsigned long err; + unsigned long lr; /* Also check accessibility of one struct frame_tail beyond */ if (!access_ok(VERIFY_READ, tail, sizeof(buftail))) @@ -47,7 +48,9 @@ user_backtrace(struct frame_tail __user *tail, if (err) return NULL; - perf_callchain_store(entry, buftail.lr); + lr = ptrauth_strip_insn_pac(buftail.lr); + + perf_callchain_store(entry, lr); /* * Frame pointers should strictly progress back up the stack -- 2.11.0
WARNING: multiple messages have this Message-ID (diff)
From: mark.rutland@arm.com (Mark Rutland) To: linux-arm-kernel@lists.infradead.org Subject: [PATCHv3 09/11] arm64: perf: strip PAC when unwinding userspace Date: Tue, 17 Apr 2018 19:37:33 +0100 [thread overview] Message-ID: <20180417183735.56985-10-mark.rutland@arm.com> (raw) In-Reply-To: <20180417183735.56985-1-mark.rutland@arm.com> When the kernel is unwinding userspace callchains, we can't expect that the userspace consumer of these callchains has the data necessary to strip the PAC from the stored LR. This patch has the kernel strip the PAC from user stackframes when the in-kernel unwinder is used. This only affects the LR value, and not the FP. This only affects the in-kernel unwinder. When userspace performs unwinding, it is up to userspace to strip PACs as necessary (which can be determined from DWARF information). Signed-off-by: Mark Rutland <mark.rutland@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Ramana Radhakrishnan <ramana.radhakrishnan@arm.com> Cc: Will Deacon <will.deacon@arm.com> --- arch/arm64/include/asm/pointer_auth.h | 7 +++++++ arch/arm64/kernel/perf_callchain.c | 5 ++++- 2 files changed, 11 insertions(+), 1 deletion(-) diff --git a/arch/arm64/include/asm/pointer_auth.h b/arch/arm64/include/asm/pointer_auth.h index 5ff141245633..a9ad81791c7f 100644 --- a/arch/arm64/include/asm/pointer_auth.h +++ b/arch/arm64/include/asm/pointer_auth.h @@ -79,6 +79,12 @@ static inline void ptrauth_keys_dup(struct ptrauth_keys *old, */ #define ptrauth_pac_mask() GENMASK(54, VA_BITS) +/* Only valid for EL0 TTBR0 instruction pointers */ +static inline unsigned long ptrauth_strip_insn_pac(unsigned long ptr) +{ + return ptr & ~ptrauth_pac_mask(); +} + #define mm_ctx_ptrauth_init(ctx) \ ptrauth_keys_init(&(ctx)->ptrauth_keys) @@ -89,6 +95,7 @@ static inline void ptrauth_keys_dup(struct ptrauth_keys *old, ptrauth_keys_dup(&(oldctx)->ptrauth_keys, &(newctx)->ptrauth_keys) #else +#define ptrauth_strip_insn_pac(lr) (lr) #define mm_ctx_ptrauth_init(ctx) #define mm_ctx_ptrauth_switch(ctx) #define mm_ctx_ptrauth_dup(oldctx, newctx) diff --git a/arch/arm64/kernel/perf_callchain.c b/arch/arm64/kernel/perf_callchain.c index bcafd7dcfe8b..928204f6ab08 100644 --- a/arch/arm64/kernel/perf_callchain.c +++ b/arch/arm64/kernel/perf_callchain.c @@ -35,6 +35,7 @@ user_backtrace(struct frame_tail __user *tail, { struct frame_tail buftail; unsigned long err; + unsigned long lr; /* Also check accessibility of one struct frame_tail beyond */ if (!access_ok(VERIFY_READ, tail, sizeof(buftail))) @@ -47,7 +48,9 @@ user_backtrace(struct frame_tail __user *tail, if (err) return NULL; - perf_callchain_store(entry, buftail.lr); + lr = ptrauth_strip_insn_pac(buftail.lr); + + perf_callchain_store(entry, lr); /* * Frame pointers should strictly progress back up the stack -- 2.11.0
next prev parent reply other threads:[~2018-04-17 18:37 UTC|newest] Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-04-17 18:37 [PATCHv3 00/11] ARMv8.3 pointer authentication userspace support Mark Rutland 2018-04-17 18:37 ` Mark Rutland 2018-04-17 18:37 ` [PATCHv3 01/11] arm64: add pointer authentication register bits Mark Rutland 2018-04-17 18:37 ` Mark Rutland 2018-04-17 18:37 ` [PATCHv3 02/11] arm64/kvm: consistently handle host HCR_EL2 flags Mark Rutland 2018-04-17 18:37 ` Mark Rutland 2018-04-27 9:51 ` Christoffer Dall 2018-04-27 9:51 ` Christoffer Dall 2018-04-27 10:13 ` Mark Rutland 2018-04-27 10:13 ` Mark Rutland 2018-04-17 18:37 ` [PATCHv3 03/11] arm64/kvm: hide ptrauth from guests Mark Rutland 2018-04-17 18:37 ` Mark Rutland 2018-04-18 13:19 ` Andrew Jones 2018-04-18 13:19 ` Andrew Jones 2018-04-18 13:47 ` Mark Rutland 2018-04-18 13:47 ` Mark Rutland 2018-04-27 9:51 ` Christoffer Dall 2018-04-27 9:51 ` Christoffer Dall 2018-04-17 18:37 ` [PATCHv3 04/11] arm64: Don't trap host pointer auth use to EL2 Mark Rutland 2018-04-17 18:37 ` Mark Rutland 2018-04-27 9:52 ` Christoffer Dall 2018-04-27 9:52 ` Christoffer Dall 2018-04-17 18:37 ` [PATCHv3 05/11] arm64/cpufeature: detect pointer authentication Mark Rutland 2018-04-17 18:37 ` Mark Rutland 2018-04-17 18:37 ` Mark Rutland 2018-04-17 18:37 ` Mark Rutland 2018-04-17 18:37 ` [PATCHv3 06/11] asm-generic: mm_hooks: allow hooks to be overridden individually Mark Rutland 2018-04-17 18:37 ` Mark Rutland 2018-04-17 19:56 ` Arnd Bergmann 2018-04-17 19:56 ` Arnd Bergmann 2018-04-18 11:38 ` Mark Rutland 2018-04-18 11:38 ` Mark Rutland 2018-04-17 18:37 ` [PATCHv3 07/11] arm64: add basic pointer authentication support Mark Rutland 2018-04-17 18:37 ` Mark Rutland 2018-04-25 11:23 ` Catalin Marinas 2018-04-25 11:23 ` Catalin Marinas 2018-04-27 10:27 ` Mark Rutland 2018-04-27 10:27 ` Mark Rutland 2018-04-17 18:37 ` [PATCHv3 08/11] arm64: expose user PAC bit positions via ptrace Mark Rutland 2018-04-17 18:37 ` Mark Rutland 2018-04-17 18:37 ` Mark Rutland [this message] 2018-04-17 18:37 ` [PATCHv3 09/11] arm64: perf: strip PAC when unwinding userspace Mark Rutland 2018-04-17 18:37 ` [PATCHv3 10/11] arm64: enable pointer authentication Mark Rutland 2018-04-17 18:37 ` Mark Rutland 2018-04-17 18:37 ` [PATCHv3 11/11] arm64: docs: document " Mark Rutland 2018-04-17 18:37 ` Mark Rutland 2018-04-22 8:05 ` Pavel Machek 2018-04-22 8:05 ` Pavel Machek 2018-04-22 8:47 ` Marc Zyngier 2018-04-22 8:47 ` Marc Zyngier 2018-04-22 8:47 ` Marc Zyngier 2018-04-22 9:00 ` Pavel Machek 2018-04-22 9:00 ` Pavel Machek 2018-04-25 12:27 ` Catalin Marinas 2018-04-25 12:27 ` Catalin Marinas
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