From: Dmitry Safonov <dima@arista.com>
To: linux-kernel@vger.kernel.org
Cc: Dmitry Safonov <0x7f454c46@gmail.com>,
Dmitry Safonov <dima@arista.com>, Adrian Reber <adrian@lisas.de>,
Andrei Vagin <avagin@openvz.org>,
Andy Lutomirski <luto@kernel.org>, Arnd Bergmann <arnd@arndb.de>,
Christian Brauner <christian.brauner@ubuntu.com>,
Cyrill Gorcunov <gorcunov@openvz.org>,
"Eric W. Biederman" <ebiederm@xmission.com>,
"H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
Jann Horn <jannh@google.com>, Jeff Dike <jdike@addtoit.com>,
Oleg Nesterov <oleg@redhat.com>,
Pavel Emelyanov <xemul@virtuozzo.com>,
Shuah Khan <shuah@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Vincenzo Frascino <vincenzo.frascino@arm.com>,
containers@lists.linux-foundation.org, criu@openvz.org,
linux-api@vger.kernel.org, x86@kernel.org,
Andrei Vagin <avagin@gmail.com>
Subject: [PATCHv5 27/37] x86/vdso2c: Process jump tables
Date: Mon, 29 Jul 2019 22:57:09 +0100 [thread overview]
Message-ID: <20190729215758.28405-28-dima@arista.com> (raw)
In-Reply-To: <20190729215758.28405-1-dima@arista.com>
As it has been discussed on timens RFC, adding a new conditional branch
`if (inside_time_ns)` on VDSO for all processes is undesirable.
Addressing those problems, there are two versions of VDSO's .so:
for host tasks (without any penalty) and for processes inside time
namespace with clk_to_ns() that subtracts offsets from host's time.
The timens code in vdso looks like this:
if (timens_static_branch()) {
clk_to_ns(clk, ts);
}
Static branch mechanism adds a __jump_table section into vdso.
Vdso's linker script drops all unwanted sections in compile time.
Preserve __jump_table section and add it into (struct vdso_image),
as it's needed for enabling (patching) static branches that are
present on vdso.
Co-developed-by: Andrei Vagin <avagin@gmail.com>
Signed-off-by: Andrei Vagin <avagin@gmail.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
arch/x86/entry/vdso/vdso-layout.lds.S | 1 +
arch/x86/entry/vdso/vdso2c.h | 9 ++++++++-
arch/x86/include/asm/vdso.h | 1 +
3 files changed, 10 insertions(+), 1 deletion(-)
diff --git a/arch/x86/entry/vdso/vdso-layout.lds.S b/arch/x86/entry/vdso/vdso-layout.lds.S
index ba216527e59f..69dbe4821aa5 100644
--- a/arch/x86/entry/vdso/vdso-layout.lds.S
+++ b/arch/x86/entry/vdso/vdso-layout.lds.S
@@ -45,6 +45,7 @@ SECTIONS
.gnu.version : { *(.gnu.version) }
.gnu.version_d : { *(.gnu.version_d) }
.gnu.version_r : { *(.gnu.version_r) }
+ __jump_table : { *(__jump_table) } :text
.dynamic : { *(.dynamic) } :text :dynamic
diff --git a/arch/x86/entry/vdso/vdso2c.h b/arch/x86/entry/vdso/vdso2c.h
index 885b988aea19..318b278ca396 100644
--- a/arch/x86/entry/vdso/vdso2c.h
+++ b/arch/x86/entry/vdso/vdso2c.h
@@ -14,7 +14,7 @@ static void BITSFUNC(go)(void *raw_addr, size_t raw_len,
unsigned long mapping_size;
ELF(Ehdr) *hdr = (ELF(Ehdr) *)raw_addr;
unsigned int i, syms_nr;
- unsigned long j;
+ unsigned long j, jump_table_addr = -1UL, jump_table_size = -1UL;
ELF(Shdr) *symtab_hdr = NULL, *strtab_hdr, *secstrings_hdr,
*alt_sec = NULL;
ELF(Dyn) *dyn = 0, *dyn_end = 0;
@@ -78,6 +78,10 @@ static void BITSFUNC(go)(void *raw_addr, size_t raw_len,
if (!strcmp(secstrings + GET_LE(&sh->sh_name),
".altinstructions"))
alt_sec = sh;
+ if (!strcmp(secstrings + GET_LE(&sh->sh_name), "__jump_table")) {
+ jump_table_addr = GET_LE(&sh->sh_offset);
+ jump_table_size = GET_LE(&sh->sh_size);
+ }
}
if (!symtab_hdr)
@@ -166,6 +170,9 @@ static void BITSFUNC(go)(void *raw_addr, size_t raw_len,
fprintf(outfile, "\t.alt_len = %lu,\n",
(unsigned long)GET_LE(&alt_sec->sh_size));
}
+ fprintf(outfile, "\t.jump_table = %luUL,\n", jump_table_addr);
+ fprintf(outfile, "\t.jump_table_len = %luUL,\n", jump_table_size);
+
for (i = 0; i < NSYMS; i++) {
if (required_syms[i].export && syms[i])
fprintf(outfile, "\t.sym_%s = %" PRIi64 ",\n",
diff --git a/arch/x86/include/asm/vdso.h b/arch/x86/include/asm/vdso.h
index ccf89dedd04f..5e83bd3cda22 100644
--- a/arch/x86/include/asm/vdso.h
+++ b/arch/x86/include/asm/vdso.h
@@ -16,6 +16,7 @@ struct vdso_image {
unsigned long size; /* Always a multiple of PAGE_SIZE */
unsigned long alt, alt_len;
+ unsigned long jump_table, jump_table_len;
long sym_vvar_start; /* Negative offset to the vvar area */
--
2.22.0
next prev parent reply other threads:[~2019-07-29 22:00 UTC|newest]
Thread overview: 68+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-29 21:56 [PATCHv5 00/37] kernel: Introduce Time Namespace Dmitry Safonov
2019-07-29 21:56 ` [PATCHv5 01/37] ns: " Dmitry Safonov
2019-08-01 5:29 ` Andy Lutomirski
2019-08-01 23:46 ` Dmitry Safonov
2019-08-07 0:24 ` [PATCHv6 " Dmitry Safonov
2019-07-29 21:56 ` [PATCHv5 02/37] timens: Add timens_offsets Dmitry Safonov
2019-07-29 21:56 ` [PATCHv5 03/37] posix-clocks: Rename the clock_get() into clock_get_timespec() Dmitry Safonov
2019-07-29 21:56 ` [PATCHv5 04/37] posix-clocks: Rename *_clock_get() functions into *_clock_get_timespec() Dmitry Safonov
2019-08-07 6:01 ` Thomas Gleixner
2019-07-29 21:56 ` [PATCHv5 05/37] alarmtimer: Rename gettime() callback to get_ktime() Dmitry Safonov
2019-07-29 21:56 ` [PATCHv5 06/37] alarmtimer: Provide get_timespec() callback Dmitry Safonov
2019-08-07 6:04 ` Thomas Gleixner
2019-08-08 6:18 ` Andrei Vagin
2019-07-29 21:56 ` [PATCHv5 07/37] posix-clocks: Introduce clock_get_ktime() callback Dmitry Safonov
2019-07-29 21:56 ` [PATCHv5 08/37] posix-timers: Use clock_get_ktime() in common_timer_get() Dmitry Safonov
2019-07-29 21:56 ` [PATCHv5 09/37] posix-clocks: Introduce CLOCK_MONOTONIC time namespace offsets Dmitry Safonov
2019-08-07 6:07 ` Thomas Gleixner
2019-07-29 21:56 ` [PATCHv5 10/37] posix-clocks: Introduce CLOCK_BOOTTIME time namespace offset Dmitry Safonov
2019-07-29 21:56 ` [PATCHv5 11/37] kernel: Add do_timens_ktime_to_host() helper Dmitry Safonov
2019-07-29 21:56 ` [PATCHv5 12/37] timerfd: Make timerfd_settime() time namespace aware Dmitry Safonov
2019-07-29 21:56 ` [PATCHv5 13/37] posix-timers: Make timer_settime() " Dmitry Safonov
2019-07-29 21:56 ` [PATCHv5 14/37] alarmtimer: Make nanosleep " Dmitry Safonov
2019-07-29 21:56 ` [PATCHv5 15/37] hrtimers: Prepare hrtimer_nanosleep() for time namespaces Dmitry Safonov
2019-07-29 21:56 ` [PATCHv5 16/37] posix-timers: Make clock_nanosleep() time namespace aware Dmitry Safonov
2019-07-29 21:56 ` [PATCHv5 17/37] fd/proc: Respect boottime inside time namespace for /proc/uptime Dmitry Safonov
2019-07-29 21:57 ` [PATCHv5 18/37] x86/vdso2c: Correct err messages on file opening Dmitry Safonov
2019-07-29 21:57 ` [PATCHv5 19/37] x86/vdso2c: Convert iterator to unsigned Dmitry Safonov
2019-07-29 21:57 ` [PATCHv5 20/37] x86/vdso/Makefile: Add vobjs32 Dmitry Safonov
2019-07-29 21:57 ` [PATCHv5 21/37] x86/vdso: Restrict splitting VVAR VMA Dmitry Safonov
2019-08-01 5:23 ` Andy Lutomirski
2019-07-29 21:57 ` [PATCHv5 22/37] x86/vdso: Rename vdso_image {.data=>.text} Dmitry Safonov
2019-07-29 21:57 ` [PATCHv5 23/37] x86/vdso: Add offsets page in vvar Dmitry Safonov
2019-08-01 5:22 ` Andy Lutomirski
2019-07-29 21:57 ` [PATCHv5 24/37] x86/vdso: Allocate timens vdso Dmitry Safonov
2019-07-29 21:57 ` [PATCHv5 25/37] x86/vdso: Switch image on setns()/clone() Dmitry Safonov
2019-08-01 5:34 ` Andy Lutomirski
2019-08-01 6:09 ` hpa
2019-08-01 21:39 ` Andy Lutomirski
2019-08-07 0:27 ` [PATCHv6 " Dmitry Safonov
2019-07-29 21:57 ` [PATCHv5 26/37] vdso: Introduce vdso_static_branch_unlikely() Dmitry Safonov
2019-07-29 21:57 ` Dmitry Safonov [this message]
2019-07-29 21:57 ` [PATCHv5 28/37] x86/vdso: Enable static branches for the timens vdso Dmitry Safonov
2019-08-01 5:21 ` Andy Lutomirski
2019-08-01 6:48 ` Thomas Gleixner
2019-07-29 21:57 ` [PATCHv5 29/37] posix-clocks: Add align for timens_offsets Dmitry Safonov
2019-07-29 21:57 ` [PATCHv5 30/37] fs/proc: Introduce /proc/pid/timens_offsets Dmitry Safonov
2019-07-29 21:57 ` [PATCHv5 31/37] selftest/timens: Add Time Namespace test for supported clocks Dmitry Safonov
2019-07-29 21:57 ` [PATCHv5 32/37] selftest/timens: Add a test for timerfd Dmitry Safonov
2019-07-29 21:57 ` [PATCHv5 33/37] selftest/timens: Add a test for clock_nanosleep() Dmitry Safonov
2019-07-29 21:57 ` [PATCHv5 34/37] selftest/timens: Add procfs selftest Dmitry Safonov
2019-07-29 21:57 ` [PATCHv5 35/37] selftest/timens: Add timer offsets test Dmitry Safonov
2019-07-29 21:57 ` [PATCHv5 36/37] selftests/timens: Add a simple perf test for clock_gettime() Dmitry Safonov
2019-07-29 21:57 ` [PATCHv5 37/37] selftest/timens: Check that a right vdso is mapped after fork and exec Dmitry Safonov
2019-07-29 21:57 ` [PATCHv5 00/37] kernel: Introduce Time Namespace Dmitry Safonov
2019-07-29 22:07 ` Dmitry Safonov
2019-07-29 21:57 ` [PATCHv5 01/37] ns: " Dmitry Safonov
2019-07-29 21:57 ` [PATCHv5 02/37] timens: Add timens_offsets Dmitry Safonov
2019-07-29 21:57 ` [PATCHv5 03/37] posix-clocks: Rename the clock_get() into clock_get_timespec() Dmitry Safonov
2019-07-29 21:57 ` [PATCHv5 04/37] posix-clocks: Rename *_clock_get() functions into *_clock_get_timespec() Dmitry Safonov
2019-07-29 21:57 ` [PATCHv5 05/37] alarmtimer: Rename gettime() callback to get_ktime() Dmitry Safonov
2019-07-29 21:57 ` [PATCHv5 06/37] alarmtimer: Provide get_timespec() callback Dmitry Safonov
2019-07-29 21:57 ` [PATCHv5 07/37] posix-clocks: Introduce clock_get_ktime() callback Dmitry Safonov
2019-07-29 21:57 ` [PATCHv5 08/37] posix-timers: Use clock_get_ktime() in common_timer_get() Dmitry Safonov
2019-07-29 21:57 ` [PATCHv5 09/37] posix-clocks: Introduce CLOCK_MONOTONIC time namespace offsets Dmitry Safonov
2019-07-29 21:57 ` [PATCHv5 10/37] posix-clocks: Introduce CLOCK_BOOTTIME time namespace offset Dmitry Safonov
2019-07-29 21:57 ` [PATCHv5 11/37] kernel: Add do_timens_ktime_to_host() helper Dmitry Safonov
2019-07-29 21:57 ` [PATCHv5 12/37] timerfd: Make timerfd_settime() time namespace aware Dmitry Safonov
2019-07-29 21:57 ` [PATCHv5 13/37] posix-timers: Make timer_settime() " Dmitry Safonov
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