From: "H.J. Lu" <hjl.tools@gmail.com>
To: Joe Simmons-Talbott <josimmon@redhat.com>
Cc: libc-alpha@sourceware.org
Subject: Re: [PATCH v5 1/3] x86_64: Set the syscall register right before doing the syscall.
Date: Wed, 19 Apr 2023 08:35:30 -0700 [thread overview]
Message-ID: <CAMe9rOodBjL2a=-nqSM71d-X-odDR6wVVBzMdgEupd3Kcz2jSg@mail.gmail.com> (raw)
In-Reply-To: <20230419135821.4113156-2-josimmon@redhat.com>
On Wed, Apr 19, 2023 at 6:59 AM Joe Simmons-Talbott via Libc-alpha
<libc-alpha@sourceware.org> wrote:
>
> To make identifying syscalls easier during call tree analysis load the
> syscall number just before performing the syscall.
>
> Compiler optimizations can place quite a few instructions between the
> setting of the syscall number and the syscall instruction. During call
> tree analysis the number of instructions between the two can lead to
> more difficulty for both tools and humans in properly identifying the
> syscall number. Having the syscall number set in the prior instruction
> to the syscall instruction makes this task easier and less error prone.
> Being able to reliably identify syscalls made by a given API will make
> it easier to understand and verify the safety and security of glibc.
> ---
> sysdeps/unix/sysv/linux/x86_64/sysdep.h | 27 ++++++++++++++-----------
> 1 file changed, 15 insertions(+), 12 deletions(-)
>
> diff --git a/sysdeps/unix/sysv/linux/x86_64/sysdep.h b/sysdeps/unix/sysv/linux/x86_64/sysdep.h
> index cfb51be8c5..fd9eb4b02f 100644
> --- a/sysdeps/unix/sysv/linux/x86_64/sysdep.h
> +++ b/sysdeps/unix/sysv/linux/x86_64/sysdep.h
> @@ -250,6 +250,9 @@
> (long int) resultvar; \
> })
>
> +#define MSTR_HELPER(x) #x
> +#define MSTR(x) MSTR_HELPER(x)
These are unused.
> #undef internal_syscall1
> #define internal_syscall1(number, arg1) \
> ({ \
> @@ -257,9 +260,9 @@
> TYPEFY (arg1, __arg1) = ARGIFY (arg1); \
> register TYPEFY (arg1, _a1) asm ("rdi") = __arg1; \
> asm volatile ( \
> - "syscall\n\t" \
> + "movl %1, %k0\n\tsyscall\n\t" \
> : "=a" (resultvar) \
> - : "0" (number), "r" (_a1) \
> + : "g" (number), "r" (_a1) \
> : "memory", REGISTERS_CLOBBERED_BY_SYSCALL); \
> (long int) resultvar; \
> })
> @@ -273,9 +276,9 @@
> register TYPEFY (arg2, _a2) asm ("rsi") = __arg2; \
> register TYPEFY (arg1, _a1) asm ("rdi") = __arg1; \
> asm volatile ( \
> - "syscall\n\t" \
> + "movl %1, %k0\n\tsyscall\n\t" \
> : "=a" (resultvar) \
> - : "0" (number), "r" (_a1), "r" (_a2) \
> + : "g" (number), "r" (_a1), "r" (_a2) \
> : "memory", REGISTERS_CLOBBERED_BY_SYSCALL); \
> (long int) resultvar; \
> })
> @@ -291,9 +294,9 @@
> register TYPEFY (arg2, _a2) asm ("rsi") = __arg2; \
> register TYPEFY (arg1, _a1) asm ("rdi") = __arg1; \
> asm volatile ( \
> - "syscall\n\t" \
> + "movl %1, %k0\n\tsyscall\n\t" \
> : "=a" (resultvar) \
> - : "0" (number), "r" (_a1), "r" (_a2), "r" (_a3) \
> + : "g" (number), "r" (_a1), "r" (_a2), "r" (_a3) \
> : "memory", REGISTERS_CLOBBERED_BY_SYSCALL); \
> (long int) resultvar; \
> })
> @@ -311,9 +314,9 @@
> register TYPEFY (arg2, _a2) asm ("rsi") = __arg2; \
> register TYPEFY (arg1, _a1) asm ("rdi") = __arg1; \
> asm volatile ( \
> - "syscall\n\t" \
> + "movl %1, %k0\n\tsyscall\n\t" \
> : "=a" (resultvar) \
> - : "0" (number), "r" (_a1), "r" (_a2), "r" (_a3), "r" (_a4) \
> + : "g" (number), "r" (_a1), "r" (_a2), "r" (_a3), "r" (_a4) \
> : "memory", REGISTERS_CLOBBERED_BY_SYSCALL); \
> (long int) resultvar; \
> })
> @@ -333,9 +336,9 @@
> register TYPEFY (arg2, _a2) asm ("rsi") = __arg2; \
> register TYPEFY (arg1, _a1) asm ("rdi") = __arg1; \
> asm volatile ( \
> - "syscall\n\t" \
> + "movl %1, %k0\n\tsyscall\n\t" \
> : "=a" (resultvar) \
> - : "0" (number), "r" (_a1), "r" (_a2), "r" (_a3), "r" (_a4), \
> + : "g" (number), "r" (_a1), "r" (_a2), "r" (_a3), "r" (_a4), \
> "r" (_a5) \
> : "memory", REGISTERS_CLOBBERED_BY_SYSCALL); \
> (long int) resultvar; \
> @@ -358,9 +361,9 @@
> register TYPEFY (arg2, _a2) asm ("rsi") = __arg2; \
> register TYPEFY (arg1, _a1) asm ("rdi") = __arg1; \
> asm volatile ( \
> - "syscall\n\t" \
> + "movl %1, %k0\n\tsyscall\n\t" \
> : "=a" (resultvar) \
> - : "0" (number), "r" (_a1), "r" (_a2), "r" (_a3), "r" (_a4), \
> + : "g" (number), "r" (_a1), "r" (_a2), "r" (_a3), "r" (_a4), \
> "r" (_a5), "r" (_a6) \
> : "memory", REGISTERS_CLOBBERED_BY_SYSCALL); \
> (long int) resultvar; \
> --
> 2.39.2
>
--
H.J.
next prev parent reply other threads:[~2023-04-19 15:36 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-04-11 13:30 [PATCH 0/2] x86_64: aarch64: Set call number just before syscall Joe Simmons-Talbott
2023-04-11 13:30 ` [PATCH 1/2] x86_64: Set the syscall register right before doing the syscall Joe Simmons-Talbott
2023-04-17 22:35 ` Noah Goldstein
2023-04-17 22:36 ` Noah Goldstein
2023-04-11 13:30 ` [PATCH 2/2] aarch64: " Joe Simmons-Talbott
2023-04-11 13:50 ` Florian Weimer
2023-04-11 14:15 ` Adhemerval Zanella Netto
2023-04-11 15:43 ` Szabolcs Nagy
2023-04-11 16:03 ` Florian Weimer
2023-04-11 16:39 ` Adhemerval Zanella Netto
2023-04-12 15:27 ` Joe Simmons-Talbott
2023-04-12 21:11 ` [PATCH v2 0/2] x86_64: aarch64: Set call number just before syscall Joe Simmons-Talbott
2023-04-12 21:11 ` [PATCH v2 1/2] x86_64: Set the syscall register right before doing the syscall Joe Simmons-Talbott
2023-04-12 21:11 ` [PATCH v2 2/2] aarch64: " Joe Simmons-Talbott
2023-04-17 15:34 ` [PATCH v3 0/2] x86_64: aarch64: Set call number just before syscall Joe Simmons-Talbott
2023-04-17 15:34 ` [PATCH v3 1/2] x86_64: Set the syscall register right before doing the syscall Joe Simmons-Talbott
2023-04-17 15:54 ` H.J. Lu
2023-04-17 16:00 ` Joe Simmons-Talbott
2023-04-17 18:38 ` H.J. Lu
2023-04-17 15:34 ` [PATCH v3 2/2] aarch64: " Joe Simmons-Talbott
2023-04-17 21:20 ` [PATCH v4 0/2] x86_64: aarch64: Set call number just before syscall Joe Simmons-Talbott
2023-04-17 21:20 ` [PATCH v4 1/2] x86_64: Set the syscall register right before doing the syscall Joe Simmons-Talbott
2023-04-17 21:20 ` [PATCH v4 2/2] aarch64: " Joe Simmons-Talbott
2023-04-18 12:57 ` Szabolcs Nagy
2023-04-18 19:33 ` Joe Simmons-Talbott
2023-04-19 13:58 ` [PATCH v5 0/3] x86_64: aarch64: Set call number just before syscall Joe Simmons-Talbott
2023-04-19 13:58 ` [PATCH v5 1/3] x86_64: Set the syscall register right before doing the syscall Joe Simmons-Talbott
2023-04-19 15:35 ` H.J. Lu [this message]
2023-04-19 15:48 ` Joe Simmons-Talbott
2023-04-19 13:58 ` [PATCH v5 2/3] aarch64: " Joe Simmons-Talbott
2023-04-19 14:56 ` Szabolcs Nagy
2023-04-19 15:21 ` Joe Simmons-Talbott
2023-04-19 13:58 ` [PATCH v5 3/3] nptl: Use direct syscall numbers in setxid Joe Simmons-Talbott
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