Correct AT_PLATFORM for HT P4 in 2.4.21
Subsystems (2)
RFC PATCH 1/1 Correct AT_PLATFORM for HT P4 in 2.4.21
Hi all...
Current kernel fails to set AT_PLATFORM when siblings are present, so HT-P4 fails to publish itself as an i686, and ld.so does not pick automatically i686 optmized libraries.
Explanation of current bug in create_elf_tables::fs/binfmt_elf.c:u_platform is used both as the place where platform info is copied at the beginning of the process data area, and as the stack begin:
- if (k_platform), it is copied at stack top, and u_platform is set to the beginning of that info.
- if siblings are present, u_platform is moved to avoid cache conflicts and predictability
- the address of u_platform is put to user space, but it has changed and now does not point to correct info
This patch separates the two uses, stack and u_platform
Note: it also changes the shifting factor from a fixed 64 to NR_CPUS to save some space...
Comments ?
fs/binfmt_elf.c renamed from fs/binfmt_elf.c.orig +7 -5
@@ -116,11 +116,14 @@elf_caddr_t *argv;elf_caddr_t *envp;elf_addr_t *sp, *csp; +char *stack_top;char *k_platform, *u_platform;long hwcap;size_t platform_len =0 ;size_t len; + stack_top = p; +/* * Get hold of platform and hardware capabilities masks for * the machine we are running on. In some cases (Sparc),
@@ -135,8 +138,8 @@ platform_len =strlen (k_platform) +1 ; u_platform = p - platform_len;__copy_to_user (u_platform, k_platform, platform_len); - }else - u_platform = p; + stack_top = u_platform; + }#if defined(__i386__) && defined(CONFIG_SMP )/*
@@ -149,15 +152,14 @@* processors. This keeps Mr Marcelo Person happier but should be * removed for 2.5 */ -if (smp_num_siblings >1 ) - u_platform = u_platform - ((current->pid %64 ) <<7 ); + stack_top -= ((current->pid %NR_CPUS ) <<7 );#endif /* * Force 16 byte _final_ alignment here for generality. */ - sp = (elf_addr_t *)(~15UL & (unsigned long )(u_platform)); + sp = (elf_addr_t *)(~15UL & (unsigned long )(stack_top)); csp = sp; csp -= (1 +DLINFO_ITEMS )*2 + (k_platform ?2 :0 );#ifdef DLINFO_ARCH_ITEMS
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J.A. Magallon <[email protected]> \ Software is like sex: werewolf.able.es \ It's better when it's free Mandrake Linux release 9.2 (Cooker) for i586 Linux 2.4.21-jam1 (gcc 3.3 (Mandrake Linux 9.2 3.3-1mdk))