Introduce and use __user_page_aligned_bss

This avoids special casing user_stack[] as data, and allows the
!test_wants_user_mappings remapping logic to become entirely generic.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>

diff --git a/Doxyfile b/Doxyfile
index 75f2b3412ab54f07df2af897bfd48375748b2b31..c5a53aa83cf4543efef1d249ebd064ed53049d16 100644 (file)
--- a/Doxyfile
+++ b/Doxyfile
@@ -2036,6 +2036,7 @@ PREDEFINED             = __alias(x)= \
                          __noinline \
                          __noreturn \
                          __used \
+                         __user_page_aligned_bss \
                          __weak \
 
 

diff --git a/arch/x86/hvm/traps.c b/arch/x86/hvm/traps.c
index 96374aa6d5a8e89fb960bf4de8914722e3d3b93d..ab095e791e01c7a5ebdb17a96101ee904f43bdbf 100644 (file)
--- a/arch/x86/hvm/traps.c
+++ b/arch/x86/hvm/traps.c
@@ -95,6 +95,12 @@ int xtf_set_idte(unsigned int vector, struct xtf_idte *idte)
     return 0;
 }
 
+static void remap_user(unsigned int start_gfn, unsigned int end_gfn)
+{
+    while ( start_gfn < end_gfn )
+        l1_identmap[start_gfn++] |= _PAGE_USER;
+}
+
 void arch_init_traps(void)
 {
     setup_gate(X86_EXC_DE,  &entry_DE,  0);
@@ -131,15 +137,14 @@ void arch_init_traps(void)
      */
     if ( !test_wants_user_mappings )
     {
-        unsigned long gfn = virt_to_gfn(user_stack);
-
-        l1_identmap[gfn] |= _PAGE_USER;
-
         extern const char __start_user_text[], __end_user_text[];
-        unsigned long end = virt_to_gfn(__end_user_text);
+        extern const char __start_user_bss[],  __end_user_bss[];
+
+        remap_user(virt_to_gfn(__start_user_text),
+                   virt_to_gfn(__end_user_text));
 
-        for ( gfn = virt_to_gfn(__start_user_text); gfn < end; ++gfn )
-            l1_identmap[gfn] |= _PAGE_USER;
+        remap_user(virt_to_gfn(__start_user_bss),
+                   virt_to_gfn(__end_user_bss));
 
         write_cr3(_u(cr3_target));
     }

diff --git a/arch/x86/link.lds.S b/arch/x86/link.lds.S
index db77d3555a4ce44a13266b496ddecce23423b65c..ca25a6cf7e2e0c69d88b532c15881b5917a538e3 100644 (file)
--- a/arch/x86/link.lds.S
+++ b/arch/x86/link.lds.S
@@ -72,6 +72,11 @@ SECTIONS
         . = ALIGN(PAGE_SIZE);
                 *(.bss.page_aligned)
         . = ALIGN(PAGE_SIZE);
+
+        __start_user_bss = .;
+                *(.bss.user.page_aligned)
+       . = ALIGN(PAGE_SIZE);
+        __end_user_bss = .;
         }
 
         _end = .;

diff --git a/arch/x86/pv/traps.c b/arch/x86/pv/traps.c
index bbc9377f64572788cea1daf071749a69ae927cf4..4b484a6f0f3d04b0fbc3eca8bf959fe5767fa34b 100644 (file)
--- a/arch/x86/pv/traps.c
+++ b/arch/x86/pv/traps.c
@@ -87,6 +87,27 @@ static bool __maybe_unused ex_pf_user(struct cpu_regs *regs,
     return false;
 }
 
+static int remap_linear(const void *linear, uint64_t flags)
+{
+    intpte_t nl1e = pte_from_virt(linear, flags);
+
+    return hypercall_update_va_mapping(_u(linear), nl1e, UVMF_INVLPG);
+}
+
+static int __maybe_unused remap_linear_range(const void *start, const void *end,
+                                             uint64_t flags)
+{
+    int ret = 0;
+
+    while ( !ret && start < end )
+    {
+        ret = remap_linear(start, flags);
+        start += PAGE_SIZE;
+    }
+
+    return ret;
+}
+
 void arch_init_traps(void)
 {
     /* PV equivalent of `lidt`. */
@@ -96,8 +117,7 @@ void arch_init_traps(void)
         panic("Failed to set trap table: %d\n", rc);
 
     /* Register gdt[] with Xen.  Need to map it read-only first. */
-    if ( hypercall_update_va_mapping(
-             _u(gdt), pte_from_virt(gdt, PF_SYM(AD, P)), UVMF_INVLPG) )
+    if ( remap_linear(gdt, PF_SYM(AD, P)) )
         panic("Unable to remap gdt[] as read-only\n");
 
     unsigned long gdt_frames[] = {
@@ -234,23 +254,14 @@ void arch_init_traps(void)
          * If we haven't applied blanket PAGE_USER mappings, remap the
          * structures which specifically want to be user.
          */
-        intpte_t nl1e = pte_from_virt(user_stack, PF_SYM(AD, U, RW, P));
-
-        if ( hypercall_update_va_mapping(_u(user_stack), nl1e, UVMF_INVLPG) )
-            panic("Unable to remap user_stack with _PAGE_USER\n");
-
         extern const char __start_user_text[], __end_user_text[];
-        unsigned long linear = _u(__start_user_text);
-
-        while ( linear < _u(__end_user_text) )
-        {
-            nl1e = pte_from_virt(_p(linear), PF_SYM(AD, U, RW, P));
+        extern const char __start_user_bss[],  __end_user_bss[];
 
-            if ( hypercall_update_va_mapping(linear, nl1e, UVMF_INVLPG) )
-                panic("Unable to remap user_text with _PAGE_USER\n");
+        remap_linear_range(__start_user_text, __end_user_text,
+                           PF_SYM(AD, U, RW, P));
 
-            linear += PAGE_SIZE;
-        }
+        remap_linear_range(__start_user_bss, __end_user_bss,
+                           PF_SYM(AD, U, RW, P));
     }
 #endif
 

diff --git a/arch/x86/setup.c b/arch/x86/setup.c
index 42e3c2bd5bbe3fb4406d9fb2ae99b038815b61eb..3c84e963f90bb83e79ddec2892e5bb7b0a06774a 100644 (file)
--- a/arch/x86/setup.c
+++ b/arch/x86/setup.c
@@ -19,7 +19,7 @@
  * boot_stack[page 1] Top of work stack
  */
 uint8_t boot_stack[3 * PAGE_SIZE] __page_aligned_bss;
-uint8_t user_stack[PAGE_SIZE] __page_aligned_bss;
+uint8_t user_stack[PAGE_SIZE] __user_page_aligned_bss;
 
 uint32_t x86_features[FSCAPINTS];
 enum x86_vendor x86_vendor;

diff --git a/include/xtf/compiler.h b/include/xtf/compiler.h
index 2cc7d22e861b0078a559918a205f51555168b8b4..3324f47e95d7a07edd4abe0fc3e5cd148520d23b 100644 (file)
--- a/include/xtf/compiler.h
+++ b/include/xtf/compiler.h
@@ -34,6 +34,9 @@
 #define __page_aligned_data   __section(".data.page_aligned") __aligned(4096)
 #define __page_aligned_bss    __section(".bss.page_aligned")  __aligned(4096)
 
+#define __user_page_aligned_bss \
+    __section(".bss.user.page_aligned")  __aligned(4096)
+
 #endif /* XTF_COMPILER_H */
 
 /*