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Message-Id: <E1Qu7ph-0007V3-7A@ZenIV.linux.org.uk>
Date: Thu, 18 Aug 2011 20:00:49 +0100
From: Al Viro <viro@....linux.org.uk>
To: richard@....at
Cc: user-mode-linux-devel@...ts.sourceforge.net,
linux-kernel@...r.kernel.org
Subject: Subject: [PATCH 11/91] um: series of __get_user() is costly in
sigframe handling
It's not x86, where __get_user() is a single dereference; here it's
a single ptrace(2) call in host, which obviously costs a lot more.
IOW, it's cheaper to do copy_{to,from}_user() once than bother with
fields one by one...
Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
---
arch/um/sys-i386/signal.c | 48 ++++++++---------
arch/um/sys-x86_64/signal.c | 118 +++++++++++++++++++++----------------------
2 files changed, 80 insertions(+), 86 deletions(-)
diff --git a/arch/um/sys-i386/signal.c b/arch/um/sys-i386/signal.c
index b87195b..bcbfb0d 100644
--- a/arch/um/sys-i386/signal.c
+++ b/arch/um/sys-i386/signal.c
@@ -10,28 +10,6 @@
#include "frame_kern.h"
#include "skas.h"
-static void copy_sc(struct uml_pt_regs *regs, void *from)
-{
- struct sigcontext *sc = from;
-
- REGS_GS(regs->gp) = sc->gs;
- REGS_FS(regs->gp) = sc->fs;
- REGS_ES(regs->gp) = sc->es;
- REGS_DS(regs->gp) = sc->ds;
- REGS_EDI(regs->gp) = sc->di;
- REGS_ESI(regs->gp) = sc->si;
- REGS_EBP(regs->gp) = sc->bp;
- REGS_SP(regs->gp) = sc->sp;
- REGS_EBX(regs->gp) = sc->bx;
- REGS_EDX(regs->gp) = sc->dx;
- REGS_ECX(regs->gp) = sc->cx;
- REGS_EAX(regs->gp) = sc->ax;
- REGS_IP(regs->gp) = sc->ip;
- REGS_CS(regs->gp) = sc->cs;
- REGS_EFLAGS(regs->gp) = sc->flags;
- REGS_SS(regs->gp) = sc->ss;
-}
-
/*
* FPU tag word conversions.
*/
@@ -175,7 +153,27 @@ static int copy_sc_from_user(struct pt_regs *regs,
return err;
pid = userspace_pid[current_thread_info()->cpu];
- copy_sc(®s->regs, &sc);
+
+#define GETREG(regno, regname) regs->regs.gp[HOST_##regno] = sc.regname
+
+ GETREG(GS, gs);
+ GETREG(FS, fs);
+ GETREG(ES, es);
+ GETREG(DS, ds);
+ GETREG(EDI, di);
+ GETREG(ESI, si);
+ GETREG(EBP, bp);
+ GETREG(SP, sp);
+ GETREG(EBX, bx);
+ GETREG(EDX, dx);
+ GETREG(ECX, cx);
+ GETREG(EAX, ax);
+ GETREG(IP, ip);
+ GETREG(CS, cs);
+ GETREG(EFLAGS, flags);
+ GETREG(SS, ss);
+
+#undef GETREG
if (have_fpx_regs) {
struct user_fxsr_struct fpx;
@@ -196,8 +194,7 @@ static int copy_sc_from_user(struct pt_regs *regs,
-err);
return 1;
}
- }
- else {
+ } else {
struct user_i387_struct fp;
err = copy_from_user(&fp, sc.fpstate,
@@ -224,6 +221,7 @@ static int copy_sc_to_user(struct sigcontext __user *to,
struct sigcontext sc;
struct faultinfo * fi = ¤t->thread.arch.faultinfo;
int err, pid;
+ memset(&sc, 0, sizeof(struct sigcontext));
sc.gs = REGS_GS(regs->regs.gp);
sc.fs = REGS_FS(regs->regs.gp);
diff --git a/arch/um/sys-x86_64/signal.c b/arch/um/sys-x86_64/signal.c
index 61ad980..255b2ca 100644
--- a/arch/um/sys-x86_64/signal.c
+++ b/arch/um/sys-x86_64/signal.c
@@ -16,41 +16,39 @@
static int copy_sc_from_user(struct pt_regs *regs,
struct sigcontext __user *from)
{
+ struct sigcontext sc;
struct user_i387_struct fp;
void __user *buf;
- int err = 0;
+ int err;
-#define GETREG(regs, regno, sc, regname) \
- __get_user((regs)->regs.gp[(regno) / sizeof(unsigned long)], \
- &(sc)->regname)
-
- err |= GETREG(regs, R8, from, r8);
- err |= GETREG(regs, R9, from, r9);
- err |= GETREG(regs, R10, from, r10);
- err |= GETREG(regs, R11, from, r11);
- err |= GETREG(regs, R12, from, r12);
- err |= GETREG(regs, R13, from, r13);
- err |= GETREG(regs, R14, from, r14);
- err |= GETREG(regs, R15, from, r15);
- err |= GETREG(regs, RDI, from, di);
- err |= GETREG(regs, RSI, from, si);
- err |= GETREG(regs, RBP, from, bp);
- err |= GETREG(regs, RBX, from, bx);
- err |= GETREG(regs, RDX, from, dx);
- err |= GETREG(regs, RAX, from, ax);
- err |= GETREG(regs, RCX, from, cx);
- err |= GETREG(regs, RSP, from, sp);
- err |= GETREG(regs, RIP, from, ip);
- err |= GETREG(regs, EFLAGS, from, flags);
- err |= GETREG(regs, CS, from, cs);
+ err = copy_from_user(&sc, from, sizeof(sc));
if (err)
- return 1;
-
+ return err;
+
+#define GETREG(regno, regname) regs->regs.gp[HOST_##regno] = sc.regname
+
+ GETREG(R8, r8);
+ GETREG(R9, r9);
+ GETREG(R10, r10);
+ GETREG(R11, r11);
+ GETREG(R12, r12);
+ GETREG(R13, r13);
+ GETREG(R14, r14);
+ GETREG(R15, r15);
+ GETREG(RDI, di);
+ GETREG(RSI, si);
+ GETREG(RBP, bp);
+ GETREG(RBX, bx);
+ GETREG(RDX, dx);
+ GETREG(RAX, ax);
+ GETREG(RCX, cx);
+ GETREG(SP, sp);
+ GETREG(IP, ip);
+ GETREG(EFLAGS, flags);
+ GETREG(CS, cs);
#undef GETREG
- err = __get_user(buf, &from->fpstate);
- if (err)
- return 1;
+ buf = sc.fpstate;
err = copy_from_user(&fp, buf, sizeof(struct user_i387_struct));
if (err)
@@ -73,48 +71,46 @@ static int copy_sc_to_user(struct sigcontext __user *to,
unsigned long mask, unsigned long sp)
{
struct faultinfo * fi = ¤t->thread.arch.faultinfo;
+ struct sigcontext sc;
struct user_i387_struct fp;
int err = 0;
+ memset(&sc, 0, sizeof(struct sigcontext));
- err |= __put_user(0, &to->gs);
- err |= __put_user(0, &to->fs);
-
-#define PUTREG(regs, regno, sc, regname) \
- __put_user((regs)->regs.gp[(regno) / sizeof(unsigned long)], \
- &(sc)->regname)
+#define PUTREG(regno, regname) sc.regname = regs->regs.gp[HOST_##regno]
- err |= PUTREG(regs, RDI, to, di);
- err |= PUTREG(regs, RSI, to, si);
- err |= PUTREG(regs, RBP, to, bp);
+ PUTREG(RDI, di);
+ PUTREG(RSI, si);
+ PUTREG(RBP, bp);
/*
* Must use original RSP, which is passed in, rather than what's in
- * the pt_regs, because that's already been updated to point at the
* signal frame.
*/
- err |= __put_user(sp, &to->sp);
- err |= PUTREG(regs, RBX, to, bx);
- err |= PUTREG(regs, RDX, to, dx);
- err |= PUTREG(regs, RCX, to, cx);
- err |= PUTREG(regs, RAX, to, ax);
- err |= PUTREG(regs, R8, to, r8);
- err |= PUTREG(regs, R9, to, r9);
- err |= PUTREG(regs, R10, to, r10);
- err |= PUTREG(regs, R11, to, r11);
- err |= PUTREG(regs, R12, to, r12);
- err |= PUTREG(regs, R13, to, r13);
- err |= PUTREG(regs, R14, to, r14);
- err |= PUTREG(regs, R15, to, r15);
- err |= PUTREG(regs, CS, to, cs); /* XXX x86_64 doesn't do this */
-
- err |= __put_user(fi->cr2, &to->cr2);
- err |= __put_user(fi->error_code, &to->err);
- err |= __put_user(fi->trap_no, &to->trapno);
-
- err |= PUTREG(regs, RIP, to, ip);
- err |= PUTREG(regs, EFLAGS, to, flags);
+ sc.sp = sp;
+ PUTREG(RBX, bx);
+ PUTREG(RDX, dx);
+ PUTREG(RCX, cx);
+ PUTREG(RAX, ax);
+ PUTREG(R8, r8);
+ PUTREG(R9, r9);
+ PUTREG(R10, r10);
+ PUTREG(R11, r11);
+ PUTREG(R12, r12);
+ PUTREG(R13, r13);
+ PUTREG(R14, r14);
+ PUTREG(R15, r15);
+ PUTREG(CS, cs); /* XXX x86_64 doesn't do this */
+
+ sc.cr2 = fi->cr2;
+ sc.err = fi->error_code;
+ sc.trapno = fi->trap_no;
+
+ PUTREG(IP, ip);
+ PUTREG(EFLAGS, flags);
#undef PUTREG
- err |= __put_user(mask, &to->oldmask);
+ sc.oldmask = mask;
+
+ err = copy_to_user(to, &sc, sizeof(struct sigcontext));
if (err)
return 1;
--
1.7.2.5
--
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