[Qemu-devel] [PATCH 0/7] NPTL support for PPC, v2

[Qemu-devel] [PATCH 0/7] NPTL support for PPC, v2

[Nathan Froyd]

This patch series adds NPTL support in Linux user-mode emulation to
32-bit PowerPC targets.

The main complication comes from implementing atomic instructions
properly.  We chose to implement a simplistic model:

- reserved loads record the value loaded;

- conditional stores check that the memory at the effective address
  contains the value loaded by the previous reserved load, in addition
  to all other checks.  if so, the store succeeds; otherwise, it fails.

It is possible to implement something more sophisticated using mprotect:

- reserved loads write-protect the page from which the value is loaded;

- regular stores to the page (through SIGSEGV handling) remove the write
  protection (which is roughly how the architecture really works);

- conditional stores fail if the page was not write-protected, in
  addition to all other checks.  If the store succeeds, then the page is
  unprotected.

but the simple scheme works well enough and should be somewhat faster.
The simple scheme is what's already done for system mode, too; it's even
slightly dumber in system mode because we don't check for equality of
values.

malc asked me to compare the approach taken in this patch series versus
an mprotect-based approach.  I did so, and found that there was no
difference between the two and that this approach was faster (no
surprise).

The patch series has been tested against the glibc testsuite, where it
passes a good chunk (90%+) of the testsuite.  The other 10% are
basically things that are not going to work in QEMU anytime soon
(e.g. sharing futexes between multiple processes, using clone(2)
directly, etc.).

This is an update to the patch series I sent a month or so ago; the
changes are rather trivial: a formatting fix or two and a fix for a
ppc64 compilation error.

-Nathan

[Qemu-devel] [PATCH 1/7] target-ppc: fix cpu_clone_regs

[Nathan Froyd]

We only need to make sure that the clone syscall looks like it
succeeded, not clobber 60% of the register set.

Signed-off-by: Nathan Froyd <froydnj@codesourcery.com>
---
 target-ppc/cpu.h |    4 +---
 1 files changed, 1 insertions(+), 3 deletions(-)

diff --git a/target-ppc/cpu.h b/target-ppc/cpu.h
index 69c1d58..148e8c3 100644
--- a/target-ppc/cpu.h
+++ b/target-ppc/cpu.h
@@ -817,11 +817,9 @@ static inline int cpu_mmu_index (CPUState *env)
 #if defined(CONFIG_USER_ONLY)
 static inline void cpu_clone_regs(CPUState *env, target_ulong newsp)
 {
-    int i;
     if (newsp)
         env->gpr[1] = newsp;
-    for (i = 7; i < 32; i++)
-        env->gpr[i] = 0;
+    env->gpr[3] = 0;
 }
 #endif
 
-- 
1.6.3.2

[Qemu-devel] [PATCH 2/7] target-ppc: add cpu_set_tls

[Nathan Froyd]

Signed-off-by: Nathan Froyd <froydnj@codesourcery.com>
---
 target-ppc/cpu.h |   11 +++++++++++
 1 files changed, 11 insertions(+), 0 deletions(-)

diff --git a/target-ppc/cpu.h b/target-ppc/cpu.h
index 148e8c3..fe2257d 100644
--- a/target-ppc/cpu.h
+++ b/target-ppc/cpu.h
@@ -1589,4 +1589,15 @@ static inline void cpu_get_tb_cpu_state(CPUState *env, target_ulong *pc,
     *flags = env->hflags;
 }
 
+static inline void cpu_set_tls(CPUState *env, target_ulong newtls)
+{
+#if defined(TARGET_PPC64)
+    /* The kernel checks TIF_32BIT here; we don't support loading 32-bit
+       binaries on PPC64 yet. */
+    env->gpr[13] = newtls;
+#else
+    env->gpr[2] = newtls;
+#endif
+}
+
 #endif /* !defined (__CPU_PPC_H__) */
-- 
1.6.3.2

[Qemu-devel] [PATCH 3/7] target-ppc: retain l{w,d}arx loaded value

[Nathan Froyd]

We do this so we can check on the corresponding stc{w,d}x. whether the
value has changed.  It's a poor man's form of implementing atomic
operations and is valid only for NPTL usermode Linux emulation.

Signed-off-by: Nathan Froyd <froydnj@codesourcery.com>
---
 target-ppc/cpu.h       |    4 +++-
 target-ppc/helper.c    |    2 +-
 target-ppc/machine.c   |    4 ++--
 target-ppc/op_helper.c |    4 ++--
 target-ppc/translate.c |   13 +++++++++----
 5 files changed, 17 insertions(+), 10 deletions(-)

diff --git a/target-ppc/cpu.h b/target-ppc/cpu.h
index fe2257d..7935fcd 100644
--- a/target-ppc/cpu.h
+++ b/target-ppc/cpu.h
@@ -561,7 +561,9 @@ struct CPUPPCState {
     /* XER */
     target_ulong xer;
     /* Reservation address */
-    target_ulong reserve;
+    target_ulong reserve_addr;
+    /* Reservation value */
+    target_ulong reserve_val;
 
     /* Those ones are used in supervisor mode only */
     /* machine state register */
diff --git a/target-ppc/helper.c b/target-ppc/helper.c
index b7162df..6eca2e5 100644
--- a/target-ppc/helper.c
+++ b/target-ppc/helper.c
@@ -2805,7 +2805,7 @@ void cpu_ppc_reset (void *opaque)
         env->msr |= (1ULL << MSR_SF);
 #endif
     hreg_compute_hflags(env);
-    env->reserve = (target_ulong)-1ULL;
+    env->reserve_addr = (target_ulong)-1ULL;
     /* Be sure no exception or interrupt is pending */
     env->pending_interrupts = 0;
     env->exception_index = POWERPC_EXCP_NONE;
diff --git a/target-ppc/machine.c b/target-ppc/machine.c
index 99ba3eb..deb2e2d 100644
--- a/target-ppc/machine.c
+++ b/target-ppc/machine.c
@@ -20,7 +20,7 @@ void cpu_save(QEMUFile *f, void *opaque)
     for (i = 0; i < 8; i++)
         qemu_put_be32s(f, &env->crf[i]);
     qemu_put_betls(f, &env->xer);
-    qemu_put_betls(f, &env->reserve);
+    qemu_put_betls(f, &env->reserve_addr);
     qemu_put_betls(f, &env->msr);
     for (i = 0; i < 4; i++)
         qemu_put_betls(f, &env->tgpr[i]);
@@ -107,7 +107,7 @@ int cpu_load(QEMUFile *f, void *opaque, int version_id)
     for (i = 0; i < 8; i++)
         qemu_get_be32s(f, &env->crf[i]);
     qemu_get_betls(f, &env->xer);
-    qemu_get_betls(f, &env->reserve);
+    qemu_get_betls(f, &env->reserve_addr);
     qemu_get_betls(f, &env->msr);
     for (i = 0; i < 4; i++)
         qemu_get_betls(f, &env->tgpr[i]);
diff --git a/target-ppc/op_helper.c b/target-ppc/op_helper.c
index ad6d8ee..812282c 100644
--- a/target-ppc/op_helper.c
+++ b/target-ppc/op_helper.c
@@ -329,8 +329,8 @@ static void do_dcbz(target_ulong addr, int dcache_line_size)
     for (i = 0 ; i < dcache_line_size ; i += 4) {
         stl(addr + i , 0);
     }
-    if (env->reserve == addr)
-        env->reserve = (target_ulong)-1ULL;
+    if (env->reserve_addr == addr)
+        env->reserve_addr = (target_ulong)-1ULL;
 }
 
 void helper_dcbz(target_ulong addr)
diff --git a/target-ppc/translate.c b/target-ppc/translate.c
index 58818c2..06282b6 100644
--- a/target-ppc/translate.c
+++ b/target-ppc/translate.c
@@ -158,7 +158,8 @@ void ppc_translate_init(void)
                                  offsetof(CPUState, xer), "xer");
 
     cpu_reserve = tcg_global_mem_new(TCG_AREG0,
-                                     offsetof(CPUState, reserve), "reserve");
+                                     offsetof(CPUState, reserve_addr),
+                                     "reserve_addr");
 
     cpu_fpscr = tcg_global_mem_new_i32(TCG_AREG0,
                                        offsetof(CPUState, fpscr), "fpscr");
@@ -3006,12 +3007,14 @@ static void gen_isync(DisasContext *ctx)
 static void gen_lwarx(DisasContext *ctx)
 {
     TCGv t0;
+    TCGv gpr = cpu_gpr[rD(ctx->opcode)];
     gen_set_access_type(ctx, ACCESS_RES);
     t0 = tcg_temp_local_new();
     gen_addr_reg_index(ctx, t0);
     gen_check_align(ctx, t0, 0x03);
-    gen_qemu_ld32u(ctx, cpu_gpr[rD(ctx->opcode)], t0);
+    gen_qemu_ld32u(ctx, gpr, t0);
     tcg_gen_mov_tl(cpu_reserve, t0);
+    tcg_gen_st_tl(gpr, cpu_env, offsetof(CPUState, reserve_val));
     tcg_temp_free(t0);
 }
 
@@ -3041,12 +3044,14 @@ static void gen_stwcx_(DisasContext *ctx)
 static void gen_ldarx(DisasContext *ctx)
 {
     TCGv t0;
+    TCGv gpr = cpu_gpr[rD(ctx->opcode)];
     gen_set_access_type(ctx, ACCESS_RES);
     t0 = tcg_temp_local_new();
     gen_addr_reg_index(ctx, t0);
     gen_check_align(ctx, t0, 0x07);
-    gen_qemu_ld64(ctx, cpu_gpr[rD(ctx->opcode)], t0);
+    gen_qemu_ld64(ctx, gpr, t0);
     tcg_gen_mov_tl(cpu_reserve, t0);
+    tcg_gen_st_tl(gpr, cpu_env, offsetof(CPUState, reserve_val));
     tcg_temp_free(t0);
 }
 
@@ -8834,7 +8839,7 @@ void cpu_dump_state (CPUState *env, FILE *f,
             a = 'E';
         cpu_fprintf(f, " %c%c", a, env->crf[i] & 0x01 ? 'O' : ' ');
     }
-    cpu_fprintf(f, " ]             RES " ADDRX "\n", env->reserve);
+    cpu_fprintf(f, " ]             RES " ADDRX "\n", env->reserve_addr);
     for (i = 0; i < 32; i++) {
         if ((i & (RFPL - 1)) == 0)
             cpu_fprintf(f, "FPR%02d", i);
-- 
1.6.3.2

[Qemu-devel] [PATCH 4/7] target-ppc: add exceptions for conditional stores

[Nathan Froyd]

Signed-off-by: Nathan Froyd <froydnj@codesourcery.com>
---
 target-ppc/cpu.h       |    5 +++
 target-ppc/translate.c |   71 ++++++++++++++++++++++++++++++++++-------------
 2 files changed, 56 insertions(+), 20 deletions(-)

diff --git a/target-ppc/cpu.h b/target-ppc/cpu.h
index 7935fcd..8c1029e 100644
--- a/target-ppc/cpu.h
+++ b/target-ppc/cpu.h
@@ -218,6 +218,7 @@ enum {
     /* Qemu exceptions: special cases we want to stop translation            */
     POWERPC_EXCP_SYNC         = 0x202, /* context synchronizing instruction  */
     POWERPC_EXCP_SYSCALL_USER = 0x203, /* System call in user mode only      */
+    POWERPC_EXCP_STCX         = 0x204 /* Conditional stores in user mode     */
 };
 
 /* Exceptions error codes                                                    */
@@ -564,6 +565,10 @@ struct CPUPPCState {
     target_ulong reserve_addr;
     /* Reservation value */
     target_ulong reserve_val;
+    /* Reservation store address */
+    target_ulong reserve_ea;
+    /* Reserved store source register and size */
+    target_ulong reserve_info;
 
     /* Those ones are used in supervisor mode only */
     /* machine state register */
diff --git a/target-ppc/translate.c b/target-ppc/translate.c
index 06282b6..f82c6e5 100644
--- a/target-ppc/translate.c
+++ b/target-ppc/translate.c
@@ -3018,24 +3018,49 @@ static void gen_lwarx(DisasContext *ctx)
     tcg_temp_free(t0);
 }
 
+#if defined(CONFIG_USER_ONLY)
+static void gen_conditional_store (DisasContext *ctx, TCGv EA,
+                                   int reg, int size)
+{
+    TCGv t0 = tcg_temp_new();
+    uint32_t save_exception = ctx->exception;
+
+    tcg_gen_st_tl(EA, cpu_env, offsetof(CPUState, reserve_ea));
+    tcg_gen_movi_tl(t0, (size << 5) | reg);
+    tcg_gen_st_tl(t0, cpu_env, offsetof(CPUState, reserve_info));
+    tcg_temp_free(t0);
+    gen_update_nip(ctx, ctx->nip-4);
+    ctx->exception = POWERPC_EXCP_BRANCH;
+    gen_exception(ctx, POWERPC_EXCP_STCX);
+    ctx->exception = save_exception;
+}
+#endif
+
 /* stwcx. */
 static void gen_stwcx_(DisasContext *ctx)
 {
-    int l1;
     TCGv t0;
     gen_set_access_type(ctx, ACCESS_RES);
     t0 = tcg_temp_local_new();
     gen_addr_reg_index(ctx, t0);
     gen_check_align(ctx, t0, 0x03);
-    tcg_gen_trunc_tl_i32(cpu_crf[0], cpu_xer);
-    tcg_gen_shri_i32(cpu_crf[0], cpu_crf[0], XER_SO);
-    tcg_gen_andi_i32(cpu_crf[0], cpu_crf[0], 1);
-    l1 = gen_new_label();
-    tcg_gen_brcond_tl(TCG_COND_NE, t0, cpu_reserve, l1);
-    tcg_gen_ori_i32(cpu_crf[0], cpu_crf[0], 1 << CRF_EQ);
-    gen_qemu_st32(ctx, cpu_gpr[rS(ctx->opcode)], t0);
-    gen_set_label(l1);
-    tcg_gen_movi_tl(cpu_reserve, -1);
+#if defined(CONFIG_USER_ONLY)
+    gen_conditional_store(ctx, t0, rS(ctx->opcode), 4);
+#else
+    {
+        int l1;
+
+        tcg_gen_trunc_tl_i32(cpu_crf[0], cpu_xer);
+        tcg_gen_shri_i32(cpu_crf[0], cpu_crf[0], XER_SO);
+        tcg_gen_andi_i32(cpu_crf[0], cpu_crf[0], 1);
+        l1 = gen_new_label();
+        tcg_gen_brcond_tl(TCG_COND_NE, t0, cpu_reserve, l1);
+        tcg_gen_ori_i32(cpu_crf[0], cpu_crf[0], 1 << CRF_EQ);
+        gen_qemu_st32(ctx, cpu_gpr[rS(ctx->opcode)], t0);
+        gen_set_label(l1);
+        tcg_gen_movi_tl(cpu_reserve, -1);
+    }
+#endif
     tcg_temp_free(t0);
 }
 
@@ -3058,21 +3083,27 @@ static void gen_ldarx(DisasContext *ctx)
 /* stdcx. */
 static void gen_stdcx_(DisasContext *ctx)
 {
-    int l1;
     TCGv t0;
     gen_set_access_type(ctx, ACCESS_RES);
     t0 = tcg_temp_local_new();
     gen_addr_reg_index(ctx, t0);
     gen_check_align(ctx, t0, 0x07);
-    tcg_gen_trunc_tl_i32(cpu_crf[0], cpu_xer);
-    tcg_gen_shri_i32(cpu_crf[0], cpu_crf[0], XER_SO);
-    tcg_gen_andi_i32(cpu_crf[0], cpu_crf[0], 1);
-    l1 = gen_new_label();
-    tcg_gen_brcond_tl(TCG_COND_NE, t0, cpu_reserve, l1);
-    tcg_gen_ori_i32(cpu_crf[0], cpu_crf[0], 1 << CRF_EQ);
-    gen_qemu_st64(ctx, cpu_gpr[rS(ctx->opcode)], t0);
-    gen_set_label(l1);
-    tcg_gen_movi_tl(cpu_reserve, -1);
+#if defined(CONFIG_USER_ONLY)
+    gen_conditional_store(ctx, t0, rS(ctx->opcode), 8);
+#else
+    {
+        int l1;
+        tcg_gen_trunc_tl_i32(cpu_crf[0], cpu_xer);
+        tcg_gen_shri_i32(cpu_crf[0], cpu_crf[0], XER_SO);
+        tcg_gen_andi_i32(cpu_crf[0], cpu_crf[0], 1);
+        l1 = gen_new_label();
+        tcg_gen_brcond_tl(TCG_COND_NE, t0, cpu_reserve, l1);
+        tcg_gen_ori_i32(cpu_crf[0], cpu_crf[0], 1 << CRF_EQ);
+        gen_qemu_st64(ctx, cpu_gpr[rS(ctx->opcode)], t0);
+        gen_set_label(l1);
+        tcg_gen_movi_tl(cpu_reserve, -1);
+    }
+#endif
     tcg_temp_free(t0);
 }
 #endif /* defined(TARGET_PPC64) */
-- 
1.6.3.2

[Qemu-devel] [PATCH 5/7] linux-user: handle POWERPC_EXCP_STCX

[Nathan Froyd]

We handle conditional stores as an exception so we can ensure that no
other thread is changing memory out from underneath us.

Signed-off-by: Nathan Froyd <froydnj@codesourcery.com>
---
 linux-user/main.c |   68 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 68 insertions(+), 0 deletions(-)

diff --git a/linux-user/main.c b/linux-user/main.c
index 20a2576..bc903de 100644
--- a/linux-user/main.c
+++ b/linux-user/main.c
@@ -1060,6 +1060,63 @@ do {                                                                    \
         log_cpu_state(env, 0);                                          \
 } while (0)
 
+static int do_store_exclusive(CPUPPCState *env)
+{
+    target_ulong addr;
+    target_ulong page_addr;
+    target_ulong val;
+    int flags;
+    int segv = 0;
+
+    addr = env->reserve_ea;
+    page_addr = addr & TARGET_PAGE_MASK;
+    start_exclusive();
+    mmap_lock();
+    flags = page_get_flags(page_addr);
+    if ((flags & PAGE_READ) == 0) {
+        segv = 1;
+    } else {
+        int reg = env->reserve_info & 0x1f;
+        int size = (env->reserve_info >> 5) & 0xf;
+        int stored = 0;
+
+        if (addr == env->reserve_addr) {
+            switch (size) {
+            case 1: segv = get_user_u8(val, addr); break;
+            case 2: segv = get_user_u16(val, addr); break;
+            case 4: segv = get_user_u32(val, addr); break;
+#if defined(TARGET_PPC64)
+            case 8: segv = get_user_u64(val, addr); break;
+#endif
+            default: abort();
+            }
+            if (!segv && val == env->reserve_val) {
+                val = env->gpr[reg];
+                switch (size) {
+                case 1: segv = put_user_u8(val, addr); break;
+                case 2: segv = put_user_u16(val, addr); break;
+                case 4: segv = put_user_u32(val, addr); break;
+#if defined(TARGET_PPC64)
+                case 8: segv = put_user_u64(val, addr); break;
+#endif
+                default: abort();
+                }
+                if (!segv) {
+                    stored = 1;
+                }
+            }
+        }
+        env->crf[0] = (stored << 1) | xer_so;
+        env->reserve_addr = (target_ulong)-1;
+    }
+    if (!segv) {
+        env->nip += 4;
+    }
+    mmap_unlock();
+    end_exclusive();
+    return segv;
+}
+
 void cpu_loop(CPUPPCState *env)
 {
     target_siginfo_t info;
@@ -1067,7 +1124,9 @@ void cpu_loop(CPUPPCState *env)
     uint32_t ret;
 
     for(;;) {
+        cpu_exec_start(env);
         trapnr = cpu_ppc_exec(env);
+        cpu_exec_end(env);
         switch(trapnr) {
         case POWERPC_EXCP_NONE:
             /* Just go on */
@@ -1447,6 +1506,15 @@ void cpu_loop(CPUPPCState *env)
             printf("syscall returned 0x%08x (%d)\n", ret, ret);
 #endif
             break;
+        case POWERPC_EXCP_STCX:
+            if (do_store_exclusive(env)) {
+                info.si_signo = TARGET_SIGSEGV;
+                info.si_errno = 0;
+                info.si_code = TARGET_SEGV_MAPERR;
+                info._sifields._sigfault._addr = env->nip;
+                queue_signal(env, info.si_signo, &info);
+            }
+            break;
         case EXCP_DEBUG:
             {
                 int sig;
-- 
1.6.3.2

[Qemu-devel] [PATCH 6/7] enable NPTL for ppc-linux-user targets in configure

[Nathan Froyd]

Enabling support for ppc64-linux-user should be easy enough to do later.

Signed-off-by: Nathan Froyd <froydnj@codesourcery.com>
---
 configure |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/configure b/configure
index 36db3b2..def8948 100755
--- a/configure
+++ b/configure
@@ -1921,12 +1921,14 @@ case "$target_arch2" in
   ppc)
     gdb_xml_files="power-core.xml power-fpu.xml power-altivec.xml power-spe.xml"
     target_phys_bits=32
+    target_nptl="yes"
   ;;
   ppcemb)
     TARGET_BASE_ARCH=ppc
     TARGET_ABI_DIR=ppc
     gdb_xml_files="power-core.xml power-fpu.xml power-altivec.xml power-spe.xml"
     target_phys_bits=64
+    target_nptl="yes"
   ;;
   ppc64)
     TARGET_BASE_ARCH=ppc
-- 
1.6.3.2

[Qemu-devel] [PATCH 7/7] linux-user: make FUTEX_* calls honor timeout parameter

[Nathan Froyd]

Signed-off-by: Nathan Froyd <froydnj@codesourcery.com>
---
 linux-user/syscall.c |   24 ++++++++++++++++--------
 1 files changed, 16 insertions(+), 8 deletions(-)

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index b5f669e..673eed4 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -4026,14 +4026,16 @@ static int do_futex(target_ulong uaddr, int op, int val, target_ulong timeout,
                     target_ulong uaddr2, int val3)
 {
     struct timespec ts, *pts;
+    int base_op;
 
     /* ??? We assume FUTEX_* constants are the same on both host
        and target.  */
 #ifdef FUTEX_CMD_MASK
-    switch ((op&FUTEX_CMD_MASK)) {
+    base_op = op & FUTEX_CMD_MASK;
 #else
-    switch (op) {
+    base_op = op;
 #endif
+    switch (base_op) {
     case FUTEX_WAIT:
         if (timeout) {
             pts = &ts;
@@ -4045,16 +4047,22 @@ static int do_futex(target_ulong uaddr, int op, int val, target_ulong timeout,
                          pts, NULL, 0));
     case FUTEX_WAKE:
         return get_errno(sys_futex(g2h(uaddr), op, val, NULL, NULL, 0));
-    case FUTEX_WAKE_OP:
-        return get_errno(sys_futex(g2h(uaddr), op, val, NULL, g2h(uaddr2), val3 ));
     case FUTEX_FD:
         return get_errno(sys_futex(g2h(uaddr), op, val, NULL, NULL, 0));
     case FUTEX_REQUEUE:
-        return get_errno(sys_futex(g2h(uaddr), op, val,
-                         NULL, g2h(uaddr2), 0));
     case FUTEX_CMP_REQUEUE:
-        return get_errno(sys_futex(g2h(uaddr), op, val,
-                         NULL, g2h(uaddr2), tswap32(val3)));
+    case FUTEX_WAKE_OP:
+        /* For FUTEX_REQUEUE, FUTEX_CMP_REQUEUE, and FUTEX_WAKE_OP, the
+           TIMEOUT parameter is interpreted as a uint32_t by the kernel.
+           But the prototype takes a `struct timespec *'; insert casts
+           to satisfy the compiler.  We do not need to tswap TIMEOUT
+           since it's not compared to guest memory.  */
+        pts = (struct timespec *)(uintptr_t) timeout;
+        return get_errno(sys_futex(g2h(uaddr), op, val, pts,
+                                   g2h(uaddr2),
+                                   (base_op == FUTEX_CMP_REQUEUE
+                                    ? tswap32(val3)
+                                    : val3)));
     default:
         return -TARGET_ENOSYS;
     }
-- 
1.6.3.2

Re: [Qemu-devel] [PATCH 0/7] NPTL support for PPC, v2

[Martin Mohring]

[-- Attachment #1: Type: text/plain, Size: 2091 bytes --]

Nathan Froyd wrote:
> This patch series adds NPTL support in Linux user-mode emulation to
> 32-bit PowerPC targets.
>
> The main complication comes from implementing atomic instructions
> properly.  We chose to implement a simplistic model:
>
> - reserved loads record the value loaded;
>
> - conditional stores check that the memory at the effective address
>   contains the value loaded by the previous reserved load, in addition
>   to all other checks.  if so, the store succeeds; otherwise, it fails.
>
> It is possible to implement something more sophisticated using mprotect:
>
> - reserved loads write-protect the page from which the value is loaded;
>
> - regular stores to the page (through SIGSEGV handling) remove the write
>   protection (which is roughly how the architecture really works);
>
> - conditional stores fail if the page was not write-protected, in
>   addition to all other checks.  If the store succeeds, then the page is
>   unprotected.
>
> but the simple scheme works well enough and should be somewhat faster.
> The simple scheme is what's already done for system mode, too; it's even
> slightly dumber in system mode because we don't check for equality of
> values.
>
> malc asked me to compare the approach taken in this patch series versus
> an mprotect-based approach.  I did so, and found that there was no
> difference between the two and that this approach was faster (no
> surprise).
>
> The patch series has been tested against the glibc testsuite, where it
> passes a good chunk (90%+) of the testsuite.  The other 10% are
> basically things that are not going to work in QEMU anytime soon
> (e.g. sharing futexes between multiple processes, using clone(2)
> directly, etc.).
>
> This is an update to the patch series I sent a month or so ago; the
> changes are rather trivial: a formatting fix or two and a fix for a
> ppc64 compilation error.
>
> -Nathan
>
>
>   
Attached you will find an addon patch to activate uid16 also for powerpc
user mode linux.
It is needed because many distros i found use uid16 calls also on powerpc.

Cheers, Martin



[-- Attachment #2: qemu-0.11-git-user-linux-ppc-uid16_fix.patch --]
[-- Type: text/x-patch, Size: 4815 bytes --]

diff -r -u qemu-0.11git2009.06.04.1212.orig/linux-user/ppc/syscall_nr.h qemu-0.11git2009.06.04.1212/linux-user/ppc/syscall_nr.h
--- qemu-0.11git2009.06.04.1212.orig/linux-user/ppc/syscall_nr.h	2009-04-25 15:24:45.000000000 +0200
+++ qemu-0.11git2009.06.04.1212/linux-user/ppc/syscall_nr.h	2009-06-05 20:15:32.047746675 +0200
@@ -17,15 +17,15 @@
 #define TARGET_NR_time                    13
 #define TARGET_NR_mknod                   14
 #define TARGET_NR_chmod                   15
-#define TARGET_NR_lchown32                16
+#define TARGET_NR_lchown                  16
 #define TARGET_NR_break                   17
 #define TARGET_NR_oldstat                 18
 #define TARGET_NR_lseek                   19
 #define TARGET_NR_getpid                  20
 #define TARGET_NR_mount                   21
 #define TARGET_NR_umount                  22
-#define TARGET_NR_setuid32                23
-#define TARGET_NR_getuid32                24
+#define TARGET_NR_setuid                  23
+#define TARGET_NR_getuid                  24
 #define TARGET_NR_stime                   25
 #define TARGET_NR_ptrace                  26
 #define TARGET_NR_alarm                   27
@@ -47,11 +47,11 @@
 #define TARGET_NR_times                   43
 #define TARGET_NR_prof                    44
 #define TARGET_NR_brk                     45
-#define TARGET_NR_setgid32                46
-#define TARGET_NR_getgid32                47
+#define TARGET_NR_setgid                  46
+#define TARGET_NR_getgid                  47
 #define TARGET_NR_signal                  48
-#define TARGET_NR_geteuid32               49
-#define TARGET_NR_getegid32               50
+#define TARGET_NR_geteuid                 49
+#define TARGET_NR_getegid                 50
 #define TARGET_NR_acct                    51
 #define TARGET_NR_umount2                 52
 #define TARGET_NR_lock                    53
@@ -71,8 +71,8 @@
 #define TARGET_NR_sigaction               67
 #define TARGET_NR_sgetmask                68
 #define TARGET_NR_ssetmask                69
-#define TARGET_NR_setreuid32              70
-#define TARGET_NR_setregid32              71
+#define TARGET_NR_setreuid                70
+#define TARGET_NR_setregid                71
 #define TARGET_NR_sigsuspend              72
 #define TARGET_NR_sigpending              73
 #define TARGET_NR_sethostname             74
@@ -81,8 +81,8 @@
 #define TARGET_NR_getrusage               77
 #define TARGET_NR_gettimeofday            78
 #define TARGET_NR_settimeofday            79
-#define TARGET_NR_getgroups32             80
-#define TARGET_NR_setgroups32             81
+#define TARGET_NR_getgroups               80
+#define TARGET_NR_setgroups               81
 #define TARGET_NR_select                  82
 #define TARGET_NR_symlink                 83
 #define TARGET_NR_oldlstat                84
@@ -96,7 +96,7 @@
 #define TARGET_NR_truncate                92
 #define TARGET_NR_ftruncate               93
 #define TARGET_NR_fchmod                  94
-#define TARGET_NR_fchown32                95
+#define TARGET_NR_fchown                  95
 #define TARGET_NR_getpriority             96
 #define TARGET_NR_setpriority             97
 #define TARGET_NR_profil                  98
@@ -139,8 +139,8 @@
 #define TARGET_NR_sysfs                  135
 #define TARGET_NR_personality            136
 #define TARGET_NR_afs_syscall            137 /* Syscall for Andrew File System */
-#define TARGET_NR_setfsuid32             138
-#define TARGET_NR_setfsgid32             139
+#define TARGET_NR_setfsuid               138
+#define TARGET_NR_setfsgid               139
 #define TARGET_NR__llseek                140
 #define TARGET_NR_getdents               141
 #define TARGET_NR__newselect             142
@@ -182,7 +182,7 @@
 #define TARGET_NR_rt_sigsuspend          178
 #define TARGET_NR_pread64                179
 #define TARGET_NR_pwrite64               180
-#define TARGET_NR_chown32                181
+#define TARGET_NR_chown                  181
 #define TARGET_NR_getcwd                 182
 #define TARGET_NR_capget                 183
 #define TARGET_NR_capset                 184
diff -r -u qemu-0.11git2009.06.16.1935/linux-user/syscall_defs.h qemu-0.11git2009.06.16.1935.new/linux-user/syscall_defs.h
--- qemu-0.11git2009.06.16.1935/linux-user/syscall_defs.h	2009-06-17 00:35:05.000000000 +0200
+++ qemu-0.11git2009.06.16.1935.new/linux-user/syscall_defs.h	2009-06-17 01:28:28.000000000 +0200
@@ -49,7 +49,7 @@
 #define TARGET_IOC_TYPEBITS	8
 
 #if defined(TARGET_I386) || defined(TARGET_ARM) || defined(TARGET_SPARC) \
-    || defined(TARGET_M68K) || defined(TARGET_SH4) || defined(TARGET_CRIS)
+    || defined(TARGET_M68K) || defined(TARGET_SH4) || defined(TARGET_CRIS) || defined(TARGET_PPC)
     /* 16 bit uid wrappers emulation */
 #define USE_UID16
 #endif