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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v1 09/11] xsplice: Add support for bug frames
On Tue, Nov 03, 2015 at 06:16:06PM +0000, Ross Lagerwall wrote:
> Add support for handling bug frames contained with xsplice modules. If a
> trap occurs search either the kernel bug table or an applied module's
payload.
> bug table depending on the instruction pointer.
>
> Signed-off-by: Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>
> ---
> xen/arch/x86/traps.c | 30 ++++++++-----
> xen/common/symbols.c | 7 +++
> xen/common/xsplice.c | 107
> +++++++++++++++++++++++++++++++++++++++++-----
> xen/include/xen/kernel.h | 1 +
> xen/include/xen/xsplice.h | 4 ++
> 5 files changed, 129 insertions(+), 20 deletions(-)
>
> diff --git a/xen/arch/x86/traps.c b/xen/arch/x86/traps.c
> index b32f696..cd51cfd 100644
> --- a/xen/arch/x86/traps.c
> +++ b/xen/arch/x86/traps.c
> @@ -48,6 +48,7 @@
> #include <xen/kexec.h>
> #include <xen/trace.h>
> #include <xen/paging.h>
> +#include <xen/xsplice.h>
> #include <xen/watchdog.h>
> #include <asm/system.h>
> #include <asm/io.h>
> @@ -1076,20 +1077,29 @@ void do_invalid_op(struct cpu_user_regs *regs)
> return;
> }
>
> - if ( !is_active_kernel_text(regs->eip) ||
> + if ( !is_active_text(regs->eip) ||
> __copy_from_user(bug_insn, eip, sizeof(bug_insn)) ||
> memcmp(bug_insn, "\xf\xb", sizeof(bug_insn)) )
> goto die;
>
> - for ( bug = __start_bug_frames, id = 0; stop_frames[id]; ++bug )
> + if ( likely(is_active_kernel_text(regs->eip)) )
> {
> - while ( unlikely(bug == stop_frames[id]) )
> - ++id;
> - if ( bug_loc(bug) == eip )
> - break;
> + for ( bug = __start_bug_frames, id = 0; stop_frames[id]; ++bug )
> + {
> + while ( unlikely(bug == stop_frames[id]) )
> + ++id;
> + if ( bug_loc(bug) == eip )
> + break;
> + }
> + if ( !stop_frames[id] )
> + goto die;
> + }
> + else
> + {
> + bug = xsplice_find_bug(eip, &id);
> + if ( !bug )
> + goto die;
> }
> - if ( !stop_frames[id] )
> - goto die;
>
> eip += sizeof(bug_insn);
> if ( id == BUGFRAME_run_fn )
> @@ -1103,7 +1113,7 @@ void do_invalid_op(struct cpu_user_regs *regs)
>
> /* WARN, BUG or ASSERT: decode the filename pointer and line number. */
> filename = bug_ptr(bug);
> - if ( !is_kernel(filename) )
> + if ( !is_kernel(filename) && !is_module(filename) )
> goto die;
> fixup = strlen(filename);
> if ( fixup > 50 )
> @@ -1130,7 +1140,7 @@ void do_invalid_op(struct cpu_user_regs *regs)
> case BUGFRAME_assert:
> /* ASSERT: decode the predicate string pointer. */
> predicate = bug_msg(bug);
> - if ( !is_kernel(predicate) )
> + if ( !is_kernel(predicate) && !is_module(predicate) )
is_payload ?
> predicate = "<unknown>";
>
> printk("Assertion '%s' failed at %s%s:%d\n",
> diff --git a/xen/common/symbols.c b/xen/common/symbols.c
> index a59c59d..bf5623f 100644
> --- a/xen/common/symbols.c
> +++ b/xen/common/symbols.c
> @@ -17,6 +17,7 @@
> #include <xen/lib.h>
> #include <xen/string.h>
> #include <xen/spinlock.h>
> +#include <xen/xsplice.h>
> #include <public/platform.h>
> #include <xen/guest_access.h>
>
> @@ -101,6 +102,12 @@ bool_t is_active_kernel_text(unsigned long addr)
> (system_state < SYS_STATE_active && is_kernel_inittext(addr)));
> }
>
> +bool_t is_active_text(unsigned long addr)
> +{
> + return is_active_kernel_text(addr) ||
> + is_active_module_text(addr);
Ditto?
> +}
> +
> const char *symbols_lookup(unsigned long addr,
> unsigned long *symbolsize,
> unsigned long *offset,
> diff --git a/xen/common/xsplice.c b/xen/common/xsplice.c
> index 4476be5..982954b 100644
> --- a/xen/common/xsplice.c
> +++ b/xen/common/xsplice.c
> @@ -40,6 +40,11 @@ struct payload {
> int nfuncs;
> void *module_address;
> size_t module_pages;
> + size_t core_size;
> + size_t core_text_size;
> +
> + struct bug_frame *start_bug_frames[4];
> + struct bug_frame *stop_bug_frames[4];
You need a #define for the 4 value.
>
> char id[XEN_XSPLICE_NAME_SIZE + 1]; /* Name of it. */
> };
> @@ -525,26 +530,27 @@ static void free_module(struct payload *payload)
> payload->module_pages = 0;
> }
>
> -static void alloc_section(struct xsplice_elf_sec *sec, size_t *core_size)
> +static void alloc_section(struct xsplice_elf_sec *sec, size_t *size)
> {
> - size_t align_size = ROUNDUP(*core_size, sec->sec->sh_addralign);
> + size_t align_size = ROUNDUP(*size, sec->sec->sh_addralign);
> sec->sec->sh_entsize = align_size;
> - *core_size = sec->sec->sh_size + align_size;
> + *size = sec->sec->sh_size + align_size;
> }
That looks to be unrelated to this patch. Perhaps squash it in earlier?
>
> static int move_module(struct payload *payload, struct xsplice_elf *elf)
> {
> uint8_t *buf;
> int i;
> - size_t core_size = 0;
> + size_t size = 0;
>
> /* Allocate text regions */
> for ( i = 0; i < elf->hdr->e_shnum; i++ )
> {
> if ( (elf->sec[i].sec->sh_flags & (SHF_ALLOC|SHF_EXECINSTR)) ==
> (SHF_ALLOC|SHF_EXECINSTR) )
> - alloc_section(&elf->sec[i], &core_size);
> + alloc_section(&elf->sec[i], &size);
> }
> + payload->core_text_size = size;
>
> /* Allocate rw data */
> for ( i = 0; i < elf->hdr->e_shnum; i++ )
> @@ -552,7 +558,7 @@ static int move_module(struct payload *payload, struct
> xsplice_elf *elf)
> if ( (elf->sec[i].sec->sh_flags & SHF_ALLOC) &&
> !(elf->sec[i].sec->sh_flags & SHF_EXECINSTR) &&
> (elf->sec[i].sec->sh_flags & SHF_WRITE) )
> - alloc_section(&elf->sec[i], &core_size);
> + alloc_section(&elf->sec[i], &size);
> }
>
> /* Allocate ro data */
> @@ -561,15 +567,16 @@ static int move_module(struct payload *payload, struct
> xsplice_elf *elf)
> if ( (elf->sec[i].sec->sh_flags & SHF_ALLOC) &&
> !(elf->sec[i].sec->sh_flags & SHF_EXECINSTR) &&
> !(elf->sec[i].sec->sh_flags & SHF_WRITE) )
> - alloc_section(&elf->sec[i], &core_size);
> + alloc_section(&elf->sec[i], &size);
> }
> + payload->core_size = size;
>
> - buf = alloc_module(core_size);
> + buf = alloc_module(size);
> if ( !buf ) {
> printk(XENLOG_ERR "Could not allocate memory for module\n");
> return -ENOMEM;
> }
> - memset(buf, 0, core_size);
> + memset(buf, 0, size);
>
> for ( i = 0; i < elf->hdr->e_shnum; i++ )
> {
> @@ -584,7 +591,7 @@ static int move_module(struct payload *payload, struct
> xsplice_elf *elf)
> }
>
> payload->module_address = buf;
> - payload->module_pages = PFN_UP(core_size);
> + payload->module_pages = PFN_UP(size);
>
> return 0;
> }
> @@ -659,6 +666,7 @@ static int find_special_sections(struct payload *payload,
> struct xsplice_elf *elf)
> {
> struct xsplice_elf_sec *sec;
> + int i;
unsigned int
>
> sec = xsplice_elf_sec_by_name(elf, ".xsplice.funcs");
> if ( !sec )
> @@ -670,6 +678,19 @@ static int find_special_sections(struct payload *payload,
> payload->funcs = (struct xsplice_patch_func *)sec->load_addr;
> payload->nfuncs = sec->sec->sh_size / (sizeof *payload->funcs);
>
> + for ( i = 0; i < 4; i++ )
use the #define.
> + {
> + char str[14];
And this needs a #define as well.
> +
> + snprintf(str, sizeof str, ".bug_frames.%d", i);
> + sec = xsplice_elf_sec_by_name(elf, str);
> + if ( !sec )
> + continue;
> +
> + payload->start_bug_frames[i] = (struct bug_frame *)sec->load_addr;
> + payload->stop_bug_frames[i] = (struct bug_frame *)(sec->load_addr +
> sec->sec->sh_size);
You probably should double check that the 'sh_size' is not greater than
4.
> + }
> +
> return 0;
> }
>
> @@ -912,6 +933,72 @@ void do_xsplice(void)
> }
> }
>
> +
> +/*
> + * Functions for handling special sections.
> + */
> +struct bug_frame *xsplice_find_bug(const char *eip, int *id)
> +{
> + struct payload *data;
> + struct bug_frame *bug;
> + int i;
unsigned int;
> +
> + /* No locking since this list is only ever changed during apply or revert
> + * context. */
Please use hte different style of comments:
/*
* blah blah blah
*/
> + list_for_each_entry ( data, &applied_list, applied_list )
> + {
> + for (i = 0; i < 4; i++) {
> + if (!data->start_bug_frames[i])
> + continue;
> + if ( !((void *)eip >= data->module_address &&
> + (void *)eip < (data->module_address +
> data->core_text_size)))
> + continue;
> +
> + for ( bug = data->start_bug_frames[i]; bug !=
> data->stop_bug_frames[i]; ++bug ) {
Could we ever have the situation of where there is a NULL structure
within start_bug_frames and stop_bug_frames?
[Say the file is corrupted]
Perhaps we should double-check that in find_special_sections?
> + if ( bug_loc(bug) == eip )
> + {
> + *id = i;
> + return bug;
> + }
> + }
> + }
> + }
> +
> + return NULL;
> +}
> +
> +bool_t is_module(const void *ptr)
> +{
> + struct payload *data;
> +
> + /* No locking since this list is only ever changed during apply or revert
> + * context. */
> + list_for_each_entry ( data, &applied_list, applied_list )
> + {
> + if ( ptr >= data->module_address &&
> + ptr < (data->module_address + data->core_size))
> + return true;
> + }
> +
> + return false;
> +}
> +
> +bool_t is_active_module_text(unsigned long addr)
> +{
> + struct payload *data;
> +
> + /* No locking since this list is only ever changed during apply or revert
> + * context. */
> + list_for_each_entry ( data, &applied_list, applied_list )
> + {
> + if ( (void *)addr >= data->module_address &&
> + (void *)addr < (data->module_address + data->core_text_size))
> + return true;
> + }
> +
> + return false;
> +}
> +
Those two look very very much the same. Could one of them call the
other?
Actually why not just have one? And do some casting?
> static int __init xsplice_init(void)
> {
> register_keyhandler('x', xsplice_printall, "print xsplicing info", 1);
> diff --git a/xen/include/xen/kernel.h b/xen/include/xen/kernel.h
> index 548b64d..df57754 100644
> --- a/xen/include/xen/kernel.h
> +++ b/xen/include/xen/kernel.h
> @@ -99,6 +99,7 @@ extern enum system_state {
> } system_state;
>
> bool_t is_active_kernel_text(unsigned long addr);
> +bool_t is_active_text(unsigned long addr);
>
> #endif /* _LINUX_KERNEL_H */
>
> diff --git a/xen/include/xen/xsplice.h b/xen/include/xen/xsplice.h
> index 507829c..772fa3a 100644
> --- a/xen/include/xen/xsplice.h
> +++ b/xen/include/xen/xsplice.h
> @@ -22,6 +22,10 @@ extern void xsplice_printall(unsigned char key);
>
> void do_xsplice(void);
>
> +struct bug_frame * xsplice_find_bug(const char *eip, int *id);
> +bool_t is_module(const void *addr);
> +bool_t is_active_module_text(unsigned long addr);
> +
> /* Arch hooks */
> int xsplice_verify_elf(uint8_t *data, ssize_t len);
> int xsplice_perform_rel(struct xsplice_elf *elf,
> --
> 2.4.3
>
>
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@xxxxxxxxxxxxx
> http://lists.xen.org/xen-devel
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