From 1b1d9258181bae199dc940f4bd0298126b9a73d9 Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Fri, 18 Dec 2009 16:12:56 +0000 Subject: x86-64: Modify copy_user_generic() alternatives mechanism In order to avoid unnecessary chains of branches, rather than implementing copy_user_generic() as a function consisting of just a single (possibly patched) branch, instead properly deal with patching call instructions in the alternative instructions framework, and move the patching into the callers. As a follow-on, one could also introduce something like __EXPORT_SYMBOL_ALT() to avoid patching call sites in modules. Signed-off-by: Jan Beulich Cc: Nick Piggin Cc: Linus Torvalds Cc: Andrew Morton LKML-Reference: <4B2BB8180200007800026AE7@vpn.id2.novell.com> Signed-off-by: Ingo Molnar --- arch/x86/kernel/alternative.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'arch/x86/kernel/alternative.c') diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c index de7353c0ce9..2589ea4c60c 100644 --- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -205,7 +205,7 @@ void __init_or_module apply_alternatives(struct alt_instr *start, struct alt_instr *end) { struct alt_instr *a; - char insnbuf[MAX_PATCH_LEN]; + u8 insnbuf[MAX_PATCH_LEN]; DPRINTK("%s: alt table %p -> %p\n", __func__, start, end); for (a = start; a < end; a++) { @@ -223,6 +223,8 @@ void __init_or_module apply_alternatives(struct alt_instr *start, } #endif memcpy(insnbuf, a->replacement, a->replacementlen); + if (*insnbuf == 0xe8 && a->replacementlen == 5) + *(s32 *)(insnbuf + 1) += a->replacement - a->instr; add_nops(insnbuf + a->replacementlen, a->instrlen - a->replacementlen); text_poke_early(instr, insnbuf, a->instrlen); -- cgit v1.2.3-18-g5258 From 2cfa19780d61740f65790c5bae363b759d7c96fa Mon Sep 17 00:00:00 2001 From: Masami Hiramatsu Date: Tue, 2 Feb 2010 16:49:11 -0500 Subject: ftrace/alternatives: Introducing *_text_reserved functions Introducing *_text_reserved functions for checking the text address range is partially reserved or not. This patch provides checking routines for x86 smp alternatives and dynamic ftrace. Since both functions modify fixed pieces of kernel text, they should reserve and protect those from other dynamic text modifier, like kprobes. This will also be extended when introducing other subsystems which modify fixed pieces of kernel text. Dynamic text modifiers should avoid those. Signed-off-by: Masami Hiramatsu Cc: systemtap Cc: DLE Cc: Steven Rostedt Cc: przemyslaw@pawelczyk.it Cc: Frederic Weisbecker Cc: Ananth N Mavinakayanahalli Cc: Jim Keniston Cc: Mathieu Desnoyers Cc: Jason Baron LKML-Reference: <20100202214911.4694.16587.stgit@dhcp-100-2-132.bos.redhat.com> Signed-off-by: Ingo Molnar --- arch/x86/kernel/alternative.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) (limited to 'arch/x86/kernel/alternative.c') diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c index de7353c0ce9..3c13284ff86 100644 --- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -390,6 +390,22 @@ void alternatives_smp_switch(int smp) mutex_unlock(&smp_alt); } +/* Return 1 if the address range is reserved for smp-alternatives */ +int alternatives_text_reserved(void *start, void *end) +{ + struct smp_alt_module *mod; + u8 **ptr; + + list_for_each_entry(mod, &smp_alt_modules, next) { + if (mod->text > end || mod->text_end < start) + continue; + for (ptr = mod->locks; ptr < mod->locks_end; ptr++) + if (start <= *ptr && end >= *ptr) + return 1; + } + + return 0; +} #endif #ifdef CONFIG_PARAVIRT -- cgit v1.2.3-18-g5258 From 076dc4a65a6d99a16979e2c7917e669fb8c91ee5 Mon Sep 17 00:00:00 2001 From: Masami Hiramatsu Date: Fri, 5 Feb 2010 12:16:47 -0500 Subject: x86/alternatives: Fix build warning Fixes these warnings: arch/x86/kernel/alternative.c: In function 'alternatives_text_reserved': arch/x86/kernel/alternative.c:402: warning: comparison of distinct pointer types lacks a cast arch/x86/kernel/alternative.c:402: warning: comparison of distinct pointer types lacks a cast arch/x86/kernel/alternative.c:405: warning: comparison of distinct pointer types lacks a cast arch/x86/kernel/alternative.c:405: warning: comparison of distinct pointer types lacks a cast Caused by: 2cfa197: ftrace/alternatives: Introducing *_text_reserved functions Changes in v2: - Use local variables to compare, instead of type casts. Reported-by: Ingo Molnar Signed-off-by: Masami Hiramatsu Cc: systemtap Cc: DLE LKML-Reference: <20100205171647.15750.37221.stgit@dhcp-100-2-132.bos.redhat.com> Signed-off-by: Ingo Molnar --- arch/x86/kernel/alternative.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) (limited to 'arch/x86/kernel/alternative.c') diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c index 3c13284ff86..e63b80e5861 100644 --- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -395,12 +395,14 @@ int alternatives_text_reserved(void *start, void *end) { struct smp_alt_module *mod; u8 **ptr; + u8 *text_start = start; + u8 *text_end = end; list_for_each_entry(mod, &smp_alt_modules, next) { - if (mod->text > end || mod->text_end < start) + if (mod->text > text_end || mod->text_end < text_start) continue; for (ptr = mod->locks; ptr < mod->locks_end; ptr++) - if (start <= *ptr && end >= *ptr) + if (text_start <= *ptr && text_end >= *ptr) return 1; } -- cgit v1.2.3-18-g5258